Fasting, apple cider vinegar, seed oils, vitamin D, cold plunges. Each week brings a new habit that is meant to fix everything. Here is what published studies in people actually found, in plain words, with a link to every source.
We judge the claim as it is usually said online, not the habit itself: something can be worth doing and still be oversold. Trials assign people at random, so they can show cause; observed studies follow people over time and show a link, not proof. Last checked: October 2026.
Backed by trialsTrials
What you hear: “Walking for 10 minutes after eating blunts blood sugar spikes.”
Trials confirm a short walk soon after eating lowers the blood sugar rise, especially after dinner.
What the studies found
In a randomised crossover trial of 41 adults with type 2 diabetes, walking 10 minutes after each main meal lowered the post-meal blood sugar rise by about 12% compared with one 30-minute walk a day, and by about 22% after the evening meal. A pooled analysis of 8 trials found exercise after a meal reduced blood sugar rises compared with resting or exercising before eating, with the effect larger the sooner after the meal. These are short trials measuring blood sugar, not long-term health outcomes.
What you could do: A gentle walk soon after your largest meal is an easy, low-risk way to soften the blood sugar rise.
See it in the habit library, with what it means for your score
Sources: Reynolds et al. Diabetologia 2016 · Engeroff et al. Sports Med 2023 · Buffey et al. Sports Med 2022
The full check, with quotes from each study
Partly trueTrials
What you hear: “Squeezing your meals into a short daily window (like 16:8) burns more fat than ordinary dieting and helps you live longer.”
Works about as well as ordinary calorie cutting, not better; longer life shown only in mice so far.
What the studies found
A 2026 Cochrane review of 22 trials (1,995 adults) found fasting plans gave about the same weight loss as regular diet advice (a difference of 0.33 percentage points of body weight, not significant). In a 12-month trial, eating only between 8am and 4pm plus calorie limits lost 8.0 kg versus 6.3 kg for calorie limits alone, a 1.8 kg gap that was not significant. A 2025 BMJ analysis of 99 trials found only alternate-day fasting beat steady calorie cutting, by about 1.3 kg, in mostly short trials. Longer life has been shown in mice; in people, observational data instead link eating one meal a day to a 30% higher death rate (a link, not proof).
Take care: In a small trial of people with type 2 diabetes on glucose-lowering medicines, fasting days roughly doubled low-blood-sugar episodes, so anyone taking insulin or diabetes medicines should plan fasting with their doctor.
What you could do: If a shorter eating window helps you eat less, it is a fair option, but pick the plan you can stick with rather than expecting extra fat loss.
See it in the habit library, with what it means for your score
Sources: Garegnani et al. Cochrane Database Syst Rev 2026 · Liu et al. N Engl J Med 2022 · Semnani-Azad et al. BMJ 2025 · Sun et al. J Acad Nutr Diet 2023 · National Institute on Aging news, mouse fasting study · Corley et al. Diabet Med 2018
The full check, with quotes from each study
Partly trueTrials
What you hear: “A spoonful of apple cider vinegar before meals burns belly fat and stops blood sugar spikes.”
Can blunt the sugar rise after a meal a little; fat-loss trials are small and one was retracted.
What the studies found
Pooled short trials found vinegar taken with a meal lowered the post-meal blood sugar rise by a moderate standardised amount (SMD -0.60) compared with no vinegar. For weight, a 2025 review of 10 small trials (789 adults, 4 to 12 weeks) reported a benefit, but its estimate of about 7.4 kg included a 2024 trial that has since been retracted, so it should not be relied on. An earlier systematic review judged the evidence insufficient because of poor-quality research. These are trials, but small, short and of mixed quality.
Take care: Drinking vinegar without enough dilution has burned the gullet, so it should always be diluted.
What you could do: Diluted vinegar on salads or with a meal is harmless and may slightly soften a sugar rise, but it is not a fat-loss tool.
Sources: Shishehbor et al. Diabetes Res Clin Pract 2017 · Castagna et al. Nutrients 2025 · Retraction of Abou-Khalil et al. BMJ Nutr Prev Health 2025 · Launholt et al. Eur J Nutr 2020 · Chang et al. Clin Endosc 2020 (case report)
The full check, with quotes from each study
Partly trueTrials
What you hear: “Berberine is “nature's Ozempic”: a cheap natural supplement that works like the weight-loss jabs.”
Trials show about 1 to 2 kg extra weight loss on average; the jab gave about 12% more than placebo.
What the studies found
A 2026 review of 23 randomised trials found berberine lowered weight by about 0.9 kg more than control. An earlier review of 12 trials put it at about 2.1 kg. In the main semaglutide trial, adults lost 14.9% of body weight over 68 weeks versus 2.4% on placebo, a 12.4-point difference. These are trials, but the berberine studies are small and the comparison is across separate trials, not head to head.
Take care: Nausea and stomach pain are common, and it is not safe in pregnancy, breastfeeding or for infants.
What you could do: Do not swap a prescribed weight-loss or diabetes medicine for berberine; ask a pharmacist before combining it with other drugs.
Sources: Elahi Vahed et al. Int J Obes 2026 · Asbaghi et al. Clin Nutr ESPEN 2020 · Wilding et al. N Engl J Med 2021 (STEP 1) · NCCIH bulletin, Berberine and Weight Loss, Dec 2023 · NCCIH bulletin, Berberine and Weight Loss, Dec 2023
The full check, with quotes from each study
Partly trueTrials
What you hear: “Shining red or near-infrared light on your face and body reverses skin ageing and speeds up muscle recovery.”
Small trials show modest skin and soreness gains; nothing shows it reverses ageing.
What the studies found
In a trial of 136 volunteers, 30 sessions of red light improved skin roughness, collagen density and blinded photo ratings compared with no treatment. A 2022 review of home skin devices recommended light-emitting diode devices only for acne; it found no home LED trials for wrinkles that met its criteria. For recovery, a review of 19 trials (672 people) of three recovery methods found low-certainty evidence that light applied before exercise lowered muscle soreness by about 12 points on soreness scales compared with control.
What you could do: If you enjoy it, treat it as a mild cosmetic or comfort aid, not an anti-ageing treatment.
Sources: Wunsch et al. Photomed Laser Surg 2014 · Cohen et al. Arch Dermatol Res 2022 · Canez et al. J Bodyw Mov Ther 2025
The full check, with quotes from each study
Partly trueObserved
What you hear: “Using a sauna several times a week adds years to your life.”
Finnish men who used saunas often lived longer, but no trial has tested whether it adds years.
What the studies found
In 2,575 Finnish men followed for about 28 years, those using a sauna 3 to 7 times a week had a 14% lower death rate than those going twice a week or less. An earlier report on the same group found deaths of 31% among 4 to 7 times a week users versus 49% among once-a-week users, before adjustment. These are links from watching people, not trials, and come from middle-aged Finnish men only. A review of 40 sauna studies found just 13 were randomised trials, and most of the studies had under 40 people.
Take care: One small study found regular sauna use disrupted sperm production in men, which recovered after stopping.
What you could do: If you enjoy a sauna and are otherwise well, it looks safe to keep going, but don't count on it to add years.
See it in the habit library, with what it means for your score
Sources: Kunutsor et al. Eur J Epidemiol 2022 · Laukkanen et al. JAMA Intern Med 2015 · Hussain and Cohen. Evid Based Complement Alternat Med 2018
The full check, with quotes from each study
Partly trueTrials and observed
What you hear: “Getting sunlight in your eyes soon after waking resets your body clock and helps you sleep better at night.”
Morning light shifts the body clock and modestly helps sleep problems; less clear for good sleepers.
What the studies found
A review of 53 studies (1,154 people with sleep problems) found bright light therapy helped sleep, with small to medium effects. A 2023 review of insomnia trials found light cut time awake during the night by about 11 minutes measured by wrist devices, and morning light moved sleep earlier. In 88,905 UK adults wearing light sensors, the brightest days went with a 17 to 34% lower death rate, but that is a link only.
What you could do: Getting outside in daylight in the morning is free and low risk; never stare at the sun itself.
See it in the habit library, with what it means for your score
Sources: van Maanen et al. Sleep Med Rev 2016 · Chambe et al. J Sleep Res 2023 · Windred et al. Proc Natl Acad Sci USA 2024
The full check, with quotes from each study
Partly trueTrials and observed
What you hear: “Steady, easy 'zone 2' cardio is the key to living longer.”
Aerobic fitness is strongly linked to longer life, but zone 2 is not shown to beat harder effort.
What the studies found
Fitter people live longer: across 33 studies of 102,980 adults, each step up in fitness (about 1 km/h faster running speed) went with a 13% lower death rate. US adults meeting the aerobic activity guideline had a 29% lower death rate. Both are links from watching people; trials of exercise in about 50,000 older or ill people have not shown fewer deaths. On intensity, interval training raised fitness slightly more than steady endurance training (about 1.2 mL/kg/min more), and a 5-year trial of 1,567 older Norwegians found a non-significant trend to fewer deaths with intervals than with moderate steady exercise.
What you could do: Aim for regular aerobic exercise you enjoy at any intensity, ideally including some harder efforts, rather than worrying about staying in one heart-rate zone.
See it in the habit library, with what it means for your score
Sources: Kodama et al. JAMA 2009 · Zhao et al. BMJ 2020 · Ballin et al. J Intern Med 2021 · Milanovic et al. Sports Med 2015 · Stensvold et al. BMJ 2020 · Storoschuk et al. Sports Med 2025
The full check, with quotes from each study
Partly trueTrials
What you hear: “Everyone should take creatine every day, not just for muscles but to sharpen the brain and boost memory.”
Small memory gains in short trials; results differ on who benefits, and healthy young people gained little.
What the studies found
A 2024 pooled analysis of 16 randomised trials (492 adults) found a small improvement in memory scores with creatine (standardised difference 0.31), but no change in overall thinking ability or planning skills. An earlier pooled analysis of healthy people found the memory gain was clear in adults aged 66 to 76 (0.88) but essentially zero in people aged 11 to 31 (0.03). These are short trials measuring test scores, not dementia or long-term brain health.
What you could do: Creatine did not harm the kidneys in short studies and may give a small memory boost, but it is not a must-have brain pill for everyone.
See it in the habit library, with what it means for your score
Sources: Xu et al. Front Nutr 2024 · Prokopidis et al. Nutr Rev 2023 · de Souza e Silva et al. J Ren Nutr 2019
The full check, with quotes from each study
Partly trueTrials
What you hear: “Taking magnesium before bed fixes your sleep and calms anxiety.”
Helped older insomniacs fall asleep about 17 minutes faster in tiny trials; anxiety evidence is poor.
What the studies found
Three small randomised trials in 151 older adults with insomnia found magnesium cut the time to fall asleep by about 17 minutes versus placebo; total sleep rose by 16 minutes but that was not statistically clear, and all trials were at moderate-to-high risk of bias. For anxiety, a review of 18 studies in people already prone to anxiety found hints of benefit in about half, but the authors rated the evidence as poor. No good trials show it 'fixes' sleep or anxiety in the general population.
Take care: Magnesium pills can cause stomach upset such as diarrhoea.
What you could do: Magnesium-rich foods are worth eating, and a pill may help a little with falling asleep, but it is not a cure for insomnia or anxiety.
See it in the habit library, with what it means for your score
Sources: Mah and Pitre. BMC Complement Med Ther 2021 · Boyle et al. Nutrients 2017 · Garrison et al. Cochrane Database Syst Rev 2020
The full check, with quotes from each study
Partly trueTrials and observed
What you hear: “NMN or NAD+ supplements and drips raise NAD levels and reverse ageing.”
They raise NAD in the blood, but human trials show no clear anti-ageing or muscle benefit.
What the studies found
A 2026 review of 33 human studies found oral NR and NMN reliably raise NAD-related markers in the blood, but effects on real health outcomes were mixed and often null; no outcome trials of NAD+ drips or injections exist. A pooled analysis of trials in adults over 60 found NMN made no difference to muscle mass, grip strength or walking speed (walking speed difference -0.01, essentially zero). The striking anti-ageing results come from mice.
What you could do: Treat NAD boosters as an experiment with no proven payoff; exercise and sleep have far better evidence for healthy ageing.
Sources: Gallagher and Emmanuel. Ageing Res Rev 2026 · Prokopidis et al. J Cachexia Sarcopenia Muscle 2025 · Yang et al. Nutrients 2026
The full check, with quotes from each study
Partly trueTrials
What you hear: “Ashwagandha lowers cortisol and melts away stress.”
Small trials show modest drops in stress scores and cortisol; long-term safety unclear.
What the studies found
A pooled analysis of 9 randomised trials (558 people) found ashwagandha lowered Perceived Stress Scale scores by about 4.7 points and anxiety scores by about 2.2 points versus placebo, with a small drop in blood cortisol. The US NCCIH says some preparations may help stress and sleep but evidence on anxiety is unclear, and many trials are small and use different products.
Take care: Rare cases of liver injury are reported, and it should be avoided in pregnancy, breastfeeding, thyroid or autoimmune disease and before surgery; it can interact with several medicines.
What you could do: A short course may modestly ease stress for some people, but check with a doctor first if you take medication or have thyroid or liver issues.
Sources: Arumugam et al. Explore (NY) 2024 · NCCIH. Ashwagandha: Usefulness and Safety · NCCIH. Ashwagandha: Usefulness and Safety (safety)
The full check, with quotes from each study
Partly trueObserved
What you hear: “10,000 steps a day is the magic number for health.”
More steps link to lower death rates, but most of the gain comes by about 7,000; 10,000 isn't magic.
What the studies found
In 15 cohorts of 47,471 adults, people averaging about 10,900 steps had a 53% lower death rate than those averaging about 3,600, but the benefit levelled off around 6,000 to 8,000 steps for over-60s and 8,000 to 10,000 for younger adults. A 2025 review found 7,000 steps a day went with a 47% lower death rate than 2,000, with the curve flattening around 5,000 to 7,000. These studies observe people, so they show a link, not proof steps cause the difference.
What you could do: Aim to walk more than you do now; around 7,000 to 8,000 steps a day captures most of the observed benefit.
See it in the habit library, with what it means for your score
Sources: Paluch et al. Lancet Public Health 2022 · Ding et al. Lancet Public Health 2025
The full check, with quotes from each study
Partly trueTrials
What you hear: “Taking fish oil capsules every day protects your heart from attacks and disease.”
Everyday fish oil pills didn't prevent heart attacks in big trials; one prescription form helped high-risk people.
What the studies found
In the VITAL trial of 25,871 US adults, 1 gram of fish oil a day for about 5 years did not significantly lower major heart events (hazard ratio 0.92). A Cochrane review of 86 trials (162,796 people) found little or no effect on deaths or heart events overall, with a possible small drop in heart disease events (low-certainty evidence). The exception is a prescription purified form (icosapent ethyl) at 4 grams a day: in 8,179 high-risk people on statins with high triglycerides, events fell from 22.0% to 17.2%. But a similar 4-gram trial of a mixed fish oil drug in 13,078 people was stopped early with no benefit (12.0% vs 12.2%).
Take care: Fish oil supplements raised the risk of an irregular heartbeat (atrial fibrillation) by about 25% across 7 trials, more so above 1 gram a day; in the 4-gram prescription trial, slightly more people had serious bleeding (2.7% vs 2.1%), so people on blood thinners should check with their doctor.
What you could do: Eating oily fish is a fine habit, but don't count on over-the-counter capsules to protect your heart; ask your doctor if you have high triglycerides.
See it in the habit library, with what it means for your score
Sources: Manson et al. N Engl J Med 2019 (VITAL omega-3) · Nicholls et al. JAMA 2020 (STRENGTH) · Abdelhamid et al. Cochrane Database Syst Rev 2020 · Bhatt et al. N Engl J Med 2019 (REDUCE-IT) · Bhatt et al. N Engl J Med 2019 (REDUCE-IT) · Gencer et al. Circulation 2021
The full check, with quotes from each study
Partly trueTrials and observed
What you hear: “Taking a multivitamin every day keeps you healthy and adds years to your life.”
No sign multivitamins help you live longer; trials found only small cancer and memory gains in older adults.
What the studies found
In a trial of 14,641 male US doctors followed for about 11 years, a daily multivitamin did not reduce heart attacks, strokes or heart deaths (hazard ratio 1.01) and did not significantly change death rates, though total cancers were 8% lower. The US Preventive Services Task Force concluded in 2022 that evidence is insufficient to say whether multivitamins prevent heart disease or cancer. A 2024 NIH study following 390,124 healthy US adults for up to 27 years found daily users were not less likely to die, and had a 4% higher death rate in the first half of follow-up (an observed link, not proof of harm). In the COSMOS trial, adults over 60 who took a multivitamin for 2 to 3 years scored slightly better on memory tests, roughly equal to 2 years less brain aging.
Take care: The Task Force recommends against beta carotene and vitamin E supplements for preventing heart disease or cancer, because beta carotene's harms outweigh its benefits.
What you could do: A basic multivitamin is a reasonable safety net if your diet has gaps, but a varied diet matters far more than the pill.
See it in the habit library, with what it means for your score
Sources: Sesso et al. JAMA 2012 (PHS II, heart) · Gaziano et al. JAMA 2012 (PHS II, cancer) · US Preventive Services Task Force. JAMA 2022 · Loftfield et al. JAMA Netw Open 2024 · Vyas et al. Am J Clin Nutr 2024 (COSMOS)
The full check, with quotes from each study
Partly trueTrials
What you hear: “Turmeric or curcumin supplements cure inflammation and get rid of joint pain.”
Curcumin may ease knee arthritis pain a bit, but the studies are weak and it doesn't 'cure' inflammation.
What the studies found
A 2025 pooled analysis of 10 trials (786 people with knee arthritis) found turmeric extract eased pain more than a dummy pill over 4 to 6 weeks and worked about as well as common anti-inflammatory painkillers. But a 2025 review of the 7 published pooled analyses rated them all as very low methodological quality, with 37 of 48 findings resting on extremely low-quality evidence. The US National Center for Complementary and Integrative Health calls the early arthritis evidence positive but says higher-quality studies are needed. Curcumin is also poorly absorbed, because the body takes in little and clears it fast. There is no good evidence it cures inflammation in general.
Take care: Rare but serious liver injury has been reported, often after 1 to 4 months and especially with high-absorption products; avoid supplements in pregnancy and check with a doctor if you take other medicines.
What you could do: If knee arthritis bothers you, a short trial of a standard turmeric product is reasonable, but stop if you notice dark urine, yellow skin or belly pain.
See it in the habit library, with what it means for your score
Sources: Hidayat et al. J Rheum Dis 2025 · Chen et al. Front Pharmacol 2025 · NCCIH: Turmeric (accessed Oct 2026) · Anand et al. Mol Pharm 2007 · Akhtar et al. (USP) Pharm Biol 2026
The full check, with quotes from each study
Partly trueTrials
What you hear: “Everybody should take a probiotic every day to keep their gut healthy.”
Probiotics help in specific cases like antibiotic diarrhea, but healthy people gain little from a daily pill.
What the studies found
A review of 45 trials in healthy adults found probiotics briefly raised levels of the bacteria in the product but did not cause lasting changes to gut bacteria. A 2024 expert review found good evidence only for specific uses, such as during antibiotics, and not enough to recommend probiotics for everyone. The clearest benefit is preventing diarrhea from antibiotics: in a Cochrane review of 33 trials in children (6,352 kids), it hit 8% of those on probiotics vs 19% without, and a pooled analysis of 15 adult trials (7,427 people) found 40% fewer cases. The American Gastroenterological Association advises using probiotics for Crohn's disease, ulcerative colitis and irritable bowel syndrome only within research studies. In a small study in mice and people, taking probiotics after antibiotics actually slowed the return of the gut's own bacteria.
Take care: Generally safe for healthy people, but the risk is higher for those who are very ill or have weak immune systems, and premature babies have had severe infections.
What you could do: Skip the daily habit if you feel fine; consider a well-studied probiotic when taking antibiotics, and eat fiber-rich and fermented foods.
Sources: Khalesi et al. Eur J Clin Nutr 2019 · Merenstein et al. Adv Nutr 2024 · Guo et al. Cochrane Database Syst Rev 2019 · Wanyama et al. Prz Gastroenterol 2025 · Su et al. Gastroenterology 2020 (AGA guideline)
The full check, with quotes from each study
Partly trueTrials and observed
What you hear: “Diet sweeteners like aspartame are worse for you than sugar and cause cancer.”
Cancer links are weak and normal amounts are within safe limits, but sweeteners don't help long-term weight loss.
What the studies found
In 2023 the WHO cancer agency labelled aspartame 'possibly carcinogenic' (Group 2B) based on limited evidence, while the WHO/FAO food additive committee kept the safe daily limit at 40 mg per kg of body weight, which a 70 kg adult would only pass at more than 9 to 14 cans of diet soda a day. Separately, WHO advised against using sweeteners for weight control, because the evidence shows no long-term benefit for body fat, and observational studies hint at higher diabetes and heart risk that may be due to other factors. One 2023 study linked the highest blood erythritol levels with roughly 1.8 to 2.2 times the risk of heart attack, stroke or death in people already having heart checks, and found erythritol made platelets stickier in lab tests; this is an observed link, not proof. There is no good evidence that sweeteners are worse than the sugar they replace.
Take care: People with phenylketonuria must avoid aspartame. Given the erythritol findings, people with heart disease may prefer not to rely heavily on erythritol-sweetened products until more is known.
What you could do: Diet drinks are a reasonable step down from sugary ones, but water, unsweetened tea or coffee are the better long-term habit.
See it in the habit library, with what it means for your score
Sources: WHO, IARC and JECFA joint news release 2023 · WHO, IARC and JECFA joint news release 2023 · WHO news release on non-sugar sweetener guideline 2023 · WHO news release on non-sugar sweetener guideline 2023 · Witkowski et al. Nat Med 2023
The full check, with quotes from each study
Partly trueObserved
What you hear: “Eating eggs will spike your cholesterol and give you heart disease, so you should avoid them.”
Eggs can nudge cholesterol up in some people, but up to one a day isn't linked to heart disease in big studies.
What the studies found
A Nordic review of 38 systematic reviews found trials show eating more eggs may raise total cholesterol and the LDL-to-HDL ratio, though people vary a lot in how they respond. Yet large observational studies mostly don't link moderate egg eating with heart disease: three US cohorts of about 215,000 people found no higher risk with an egg a day, and a pooled analysis of 1.7 million people found each extra daily egg was not linked to heart disease. One 2019 analysis of 29,615 US adults did find each extra half egg a day went with about 6% higher risk of heart disease and stroke and 8% higher death risk, a link that disappeared once total dietary cholesterol was accounted for. These are observed links, not trial results.
Take care: People with diabetes, high LDL or familial hypercholesterolaemia may respond more strongly to dietary cholesterol and should follow their clinician's advice.
What you could do: For most people, up to an egg a day fits a healthy diet; pay more attention to what comes with it, like bacon and butter.
See it in the habit library, with what it means for your score
Sources: Virtanen & Larsson, Food Nutr Res 2024 · Drouin-Chartier et al. BMJ 2020 · Zhong et al. JAMA 2019 · Zhong et al. JAMA 2019
The full check, with quotes from each study
Partly trueObserved
What you hear: “Drinking coffee every day helps you live longer.”
Coffee drinkers do tend to live longer, but that's an observed link; trials haven't shown coffee causes it.
What the studies found
An umbrella review of 201 meta-analyses of observational studies found coffee was more often linked with benefit than harm, with the biggest drop at 3 to 4 cups a day, including about 17% lower risk of death from any cause compared with no coffee. In the UK Biobank study of about 498,000 adults followed for 10 years, coffee drinkers had roughly 6% to 16% lower death rates than non-drinkers, including decaf drinkers. These are associations: coffee drinkers may differ in health and habits in ways studies can't fully adjust for, and the review authors called for trials to test whether the link is causal. Coffee does not appear to be harmful for most adults at usual amounts.
Take care: In pregnancy, higher coffee intake was linked with low birth weight, preterm birth and pregnancy loss, so pregnant people should limit caffeine; caffeine can also disturb sleep and raise heart rate in sensitive people.
What you could do: If you enjoy coffee and sleep well, a few cups a day is fine to keep; there's no strong reason to start for longevity.
See it in the habit library, with what it means for your score
Sources: Poole et al. BMJ 2017 · Poole et al. BMJ 2017 · Poole et al. BMJ 2017 · Loftfield et al. JAMA Intern Med 2018
The full check, with quotes from each study
Partly trueTrials
What you hear: “Dark chocolate is a superfood that protects your heart, so eating it daily is good for you.”
Cocoa slightly lowers blood pressure, but a big trial didn't cut heart events, and bars carry calories and metals.
What the studies found
A Cochrane review of 35 trials (about 1,800 mostly healthy people, 2 to 18 weeks) found flavanol-rich cocoa lowered blood pressure by under 2 mmHg on average, a small effect. The large COSMOS trial gave 21,442 older adults a cocoa extract supplement or placebo for a median 3.6 years and found no significant drop in total heart events, though deaths from heart disease were 27% lower, a secondary finding. That trial used a concentrated capsule, not chocolate bars, which also bring sugar, fat and calories. In 2022 testing of 28 dark chocolate bars, Consumer Reports found lead and cadmium in all of them, and 23 would put an adult over its chosen safety level at one ounce a day.
Take care: Heavy metals in dark chocolate are of most concern for pregnant people and young children; chocolate is also calorie-dense.
What you could do: Enjoy a small square of dark chocolate as a treat, vary brands, and don't count on it to protect your heart.
See it in the habit library, with what it means for your score
Sources: Ried et al. Cochrane Database Syst Rev 2017 · Sesso et al. Am J Clin Nutr 2022 (COSMOS) · Sesso et al. Am J Clin Nutr 2022 (COSMOS) · Consumer Reports 2022/2023 · Consumer Reports 2022/2023
The full check, with quotes from each study
Partly trueTrials
What you hear: “Walking with a weighted vest burns far more fat than normal walking and builds stronger bones.”
A vest makes walks harder and may trim a bit more fat, but trials show no clear extra bone gain beyond exercise.
What the studies found
A small lab study of 10 young adults found that vests weighing 10% to 20% of body weight raised oxygen use and the load on the skeleton during treadmill walking. A 2026 pooled analysis of 9 randomised trials (368 middle-aged and older adults) found vest-plus-exercise improved hip and spine bone density compared with usual activity, and trimmed about 0.7 kg more body fat than the same exercise without a vest. But only one trial compared vest-plus-exercise with exercise alone for bone, and it found no extra bone benefit. In the 12-month INVEST trial of 150 older adults with obesity on a weight-loss diet, wearing a vest about 7 hours a day did not prevent hip bone loss compared with dieting alone; hip bone density fell 1.2% to 1.9% in every group.
What you could do: If you enjoy it, a vest can make walks a little harder, but regular exercise, including strength work, matters more than the vest.
Sources: Puthoff et al. Med Sci Sports Exerc 2006 · Wang et al. Osteoporos Int 2026 · Wang et al. Osteoporos Int 2026 · Beavers et al. JAMA Netw Open 2025 · Beavers et al. JAMA Netw Open 2025
The full check, with quotes from each study
Partly trueTrials
What you hear: “Walking 30 minutes at a 12% incline and 3 mph is the best workout for losing weight.”
It's a real calorie-burning workout, but no study shows it's the best for weight loss; a run burns the same faster.
What the studies found
The only lab study we found had 16 young, active adults (14 with complete data) do 30 minutes of 12-3-30 and, on another day, a self-paced run that burned the same calories: both burned about 308 to 310 calories, but the run took about 24 minutes instead of 30. 12-3-30 drew a larger share of its energy from fat during the session (about 41% vs 33%), but the authors point out that total calories burned, not the fuel mix during exercise, drives weight loss. No trial has tested 12-3-30 itself for weight loss. A pooled analysis of 116 trials in adults with overweight found each 30 minutes a week of aerobic exercise lowered weight by about half a kilo, with more than 150 minutes a week likely needed for clearly meaningful fat loss.
What you could do: 12-3-30 is a fine choice if you enjoy it; the best workout for weight loss is one you'll keep doing most weeks, alongside your eating habits.
Sources: Wong et al. Int J Exerc Sci 2025 · Wong et al. Int J Exerc Sci 2025 (Table 1) · Wong et al. Int J Exerc Sci 2025 · Jayedi et al. JAMA Netw Open 2024 · Jayedi et al. JAMA Netw Open 2024
The full check, with quotes from each study
Partly trueTrials
What you hear: “Wim Hof breathing supercharges your immune system and cures inflammation.”
A small trial found it calmed an inflammatory reaction in a lab test; it doesn't boost immunity or cure disease.
What the studies found
In a 2014 trial, 12 healthy volunteers trained for 10 days in the method (fast breathing with breath holds, cold exposure and meditation) and 12 were not; after a lab injection of a bacterial toxin, the trained group had lower inflammatory signals, a faster rise in an anti-inflammatory signal and fewer flu-like symptoms. That is a dampened immune reaction, not a boosted immune system, and it has not been shown to cure inflammatory diseases. A 2023 pooled analysis of 12 trials (785 adults) found breathwork of many kinds lowered self-reported stress by a small-to-moderate amount. But a 2024 blinded trial of 200 young adults found 3 weeks of this style of fast breathing with breath holds was no better than a slower dummy breathing routine for stress, anxiety or mood.
Take care: The method's own guidance says never to do the breathing before or during swimming, diving, driving or bathing, and not to practise it while pregnant or with conditions such as epilepsy.
What you could do: If you enjoy breathwork, it can be a calming habit; do it seated or lying down on dry land, and don't rely on it to treat an illness.
Sources: Kox et al. PNAS 2014 · Kox et al. PNAS 2014 · Fincham et al. Sci Rep 2023 · Fincham et al. Sci Rep 2024 · Wim Hof Method: Safety warnings
The full check, with quotes from each study
Not provenObserved
What you hear: “Eating only meat, eggs and animal fat heals the body and reverses chronic disease.”
No controlled trials; evidence is surveys, case reports and small uncontrolled studies, with high LDL common.
What the studies found
A 2026 scoping review found only nine human studies and rated the evidence very limited because of small samples, short follow-up and no control groups. The largest is a social-media survey of 2,029 followers who reported feeling well, but those who shared lab results had a typical LDL cholesterol of 172 mg/dL, well above the usual target. Large cohort studies link low-carb diets built on animal fat and protein to an 18% higher death rate (a link, not proof).
Take care: A 2026 review flags likely shortfalls in fibre, vitamin C, vitamin D, calcium, magnesium and iodine, and raised LDL cholesterol.
What you could do: If you try it, get your cholesterol checked before and after, and talk to a doctor, especially with heart risk factors.
See it in the habit library, with what it means for your score
Sources: Lietz et al. Nutrients 2026 · Seidelmann et al. Lancet Public Health 2018 · Lennerz et al. Curr Dev Nutr 2021
The full check, with quotes from each study
Not provenTrials and observed
What you hear: “Everyone should wear a continuous glucose monitor to catch and avoid harmful blood sugar spikes, even without diabetes.”
No trials show health benefits for people without diabetes, and the readings can be off.
What the studies found
In 153 healthy people, glucose stayed between 70 and 140 mg/dL about 96% of the time, with about 30 minutes a day above 140, so short rises after meals are normal. A 2024 review of 25 trials found monitor feedback lowered HbA1c by 0.28%, but most were in people with diabetes, and weight did not change. An independent test of over-the-counter monitors in 39 young adults without diabetes found readings were off by about 13% on average and less reliable right after sugary drinks.
Take care: Over-the-counter readings can be off by more than 15%, so they should not be used to self-diagnose diabetes or low blood sugar.
What you could do: A monitor can be an interesting experiment, but for people without diabetes a regular HbA1c or fasting glucose test is the proven check.
Sources: Shah et al. J Clin Endocrinol Metab 2019 · Richardson et al. Int J Behav Nutr Phys Act 2024 · Prakash et al. J Diabetes Sci Technol 2026
The full check, with quotes from each study
Not provenTrials
What you hear: “Regular ice baths or cold plunges boost your immune system, speed up your metabolism and lift your mood.”
Trials show no effect on immune markers or mood, and metabolism is untested; cold showers cut sick days off.
What the studies found
A 2025 review of 11 trials (3,177 healthy adults) found stress was lower 12 hours after cold water, but not at other time points, and inflammation rose straight after. Immune measures did not change and mood did not improve. In the largest trial, 3,018 Dutch adults ending showers with 30 to 90 seconds of cold took 29% fewer sick days off work, but were ill on just as many days. Metabolism claims have not been tested in these trials.
Take care: Sudden immersion in cold water triggers a cold shock response that can lead to drowning or heart rhythm problems, so people with heart disease should check with a doctor first.
What you could do: A short cold shower is a safe, cheap thing to try if you like how it feels; skip plunges alone or if you have heart problems.
See it in the habit library, with what it means for your score
Sources: Cain et al. PLoS One 2025 · Buijze et al. PLoS One 2016 · Tipton et al. Exp Physiol 2017
The full check, with quotes from each study
Not provenTrials and observed
What you hear: “Taping your mouth closed at night makes you breathe through your nose, so you sleep better and snore less.”
Ten small studies (213 people) show mixed results, and tape can be risky if your nose is blocked.
What the studies found
A 2025 review found only 10 studies with 213 people in total. Two showed better sleep apnoea scores with mouth tape; the others found no difference. A 2026 review could pool no data on taping, but noted two small studies where it lowered breathing pauses in mild sleep apnoea. Many studies excluded people with a blocked nose.
Take care: Researchers warn that taping the mouth could risk suffocation if your nose is blocked, and it is no substitute for sleep apnoea treatment.
What you could do: If you snore loudly or wake tired, get checked for sleep apnoea and any nasal blockage rather than taping your mouth.
Sources: Rhee et al. PLoS One 2025 · Alshehri et al. OTO Open 2026
The full check, with quotes from each study
Not provenTrials
What you hear: “Walking barefoot on grass or sleeping on a grounding mat lowers inflammation in your body.”
Only a few tiny trials, mostly by grounding advocates; no solid proof it lowers inflammation.
What the studies found
The trials are very small: one randomised 32 young men after hard squats and found a smaller rise in a muscle-damage marker with grounding, but pain was the same in both groups. Another tested 16 massage therapists and reported less pain and fatigue. The main reviews of inflammation effects are written by the researchers who run these trials and lean on animal work.
What you could do: Time outdoors and walking are good for you anyway; just don't rely on grounding products to treat inflammation or pain.
Sources: Brown et al. Open Access J Sports Med 2015 · Chevalier et al. Explore (NY) 2019 · Oschman et al. J Inflamm Res 2015
The full check, with quotes from each study
Not provenTrials
What you hear: “Wearing blue-light-blocking glasses stops screen eye strain and helps you sleep.”
A Cochrane review found they may make no difference to screen eye strain; sleep results are mixed.
What the studies found
A 2023 Cochrane review of 17 randomised trials found blue-light filtering lenses may make no difference to eye strain from screens over the short term. They probably have no effect on sharpness of vision. For sleep, six trials with 148 people split evenly: three found better sleep scores and three found no difference.
Take care: A few trials reported headaches, low mood and discomfort while wearing the glasses.
What you could do: For tired eyes, take regular screen breaks; for sleep, dimming screens and lights in the evening is a cheaper first step.
Sources: Singh et al. Cochrane Database Syst Rev 2023 · Singh et al. Cochrane Database Syst Rev 2023
The full check, with quotes from each study
Not provenTrials
What you hear: “Drinking collagen powder every day gives you younger, firmer, less wrinkled skin.”
Benefits show up mainly in industry-funded, lower-quality trials; independent trials found none.
What the studies found
A 2025 pooled analysis of 23 randomised trials (1,474 people) found improved skin hydration, elasticity and wrinkles overall, but trials not funded by companies and the high-quality trials showed no effect. An earlier pooled analysis of 19 trials reported benefits after about 90 days without that split. So results conflict and depend on who paid and how well the study was done.
What you could do: Collagen is optional: the trials that found younger-looking skin were mostly lower quality or paid for by companies.
Sources: Myung and Park. Am J Med 2025 · de Miranda et al. Int J Dermatol 2021
The full check, with quotes from each study
Not provenNo trials
What you hear: “Celery juice, juice cleanses and detox drinks flush toxins out of your body.”
No good trials show juices or cleanses remove toxins; any weight lost tends to come back.
What the studies found
A 2015 review found no randomised trials of commercial detox diets in humans and only a handful of small, flawed studies. The US NCCIH notes juice detoxes cause early weight loss from eating fewer calories, which tends to return once normal eating resumes. We found no human trials of celery juice for detoxing.
Take care: Unpasteurised juices can cause food poisoning, and high-oxalate green juices have caused kidney damage in susceptible people.
What you could do: Your liver and kidneys do the detox work; fruit and vegetables are good to eat, but a cleanse adds no proven benefit.
Sources: Klein and Kiat. J Hum Nutr Diet 2015 · NCCIH. Detoxes and Cleanses: What You Need To Know · Makkapati et al. Am J Kidney Dis 2018
The full check, with quotes from each study
Not provenNo trials
What you hear: “Sea moss contains 92 of the 102 minerals your body needs, making it a superfood everyone should eat.”
No human trials back sea moss's health claims, and the '92 of 102 minerals' line has no scientific basis.
What the studies found
We found no clinical trials testing whether sea moss (Irish moss, a red seaweed) improves any health outcome in people. The US National Library of Medicine's drug and breastfeeding database states that no medicinal value has been proven. Like other seaweeds, it contains iodine and can carry heavy metals such as arsenic, lead, cadmium and mercury from the water it grew in. A 2026 test of 66 sea moss products sold online found arsenic, cobalt and mercury in dried sea moss, and bacteria including Salmonella in some products. The body needs a small set of essential minerals, not 102, and we found no published analysis behind the '92 minerals' figure.
Take care: Seaweed iodine levels vary wildly and can push intake past safe limits, which can upset the thyroid; it is best avoided while breastfeeding or with thyroid disease unless a doctor agrees.
What you could do: Enjoy seaweed occasionally as food if you like it, and get minerals from a varied diet rather than sea moss gels or capsules.
Sources: Drugs and Lactation Database (LactMed): Sea Moss. NLM 2006- · Drugs and Lactation Database (LactMed): Sea Moss. NLM 2006- · Rejuso et al. J Food Prot 2026 · Aakre et al. Food Nutr Res 2021 · Taylor et al. Clin Endocrinol (Oxf) 2026
The full check, with quotes from each study
Not provenAnimal studies
What you hear: “Lion's mane mushroom supplements sharpen memory and grow new brain cells.”
Brain-cell growth is seen in lab and animal studies; small human trials show mixed, mostly modest results.
What the studies found
The 'grows brain cells' idea comes from lab and animal work, where lion's mane compounds (erinacines) boosted nerve growth and improved memory in rodents. In people, the trials are few and small. In a 2009 Japanese trial of 30 older adults with mild memory problems, those taking lion's mane for 16 weeks scored better on a memory scale, but the gain faded within 4 weeks of stopping. In 41 healthy young adults, a single dose sped up one reaction-time test an hour later, and 28 days of use gave only a non-significant trend toward less stress, with mostly no effect otherwise. A single dose in 18 healthy young adults did not improve overall thinking or mood.
Take care: Usually well tolerated in short studies, but stomach upset, headache and allergic reactions have been reported; people with mushroom allergies should avoid it.
What you could do: Lion's mane is a tasty edible mushroom, but treat memory-boosting pills as an experiment, not a proven brain booster.
Sources: Spangenberg et al. Front Pharmacol 2025 · Mori et al. Phytother Res 2009 · Docherty et al. Nutrients 2023 · Surendran et al. Front Nutr 2025 · Menon et al. Front Nutr 2025
The full check, with quotes from each study
Not provenTrials
What you hear: “Bovine colostrum heals a leaky gut and supercharges your immune system.”
A few small trials, mostly in athletes, hint at fewer colds and less gut leakiness; good evidence is lacking.
What the studies found
Most colostrum research involves small groups of athletes. In a crossover trial of 12 volunteers, two weeks of colostrum blunted the rise in gut leakiness after hard exercise, a lab marker rather than a health outcome. A pooled analysis of 5 trials (152 people in exercise training) found fewer days with cold-like symptoms over 8 to 12 weeks, but the authors said a larger, well-designed trial is needed. A 2025 pooled analysis of supplements for exercise-related gut damage, which included several colostrum trials, found no significant effect of colostrum on a blood marker of gut damage, and judged the changes seen with any supplement too small to matter clinically. A review of 8 studies in children could draw no conclusion on gut health.
Take care: Colostrum comes from cow's milk, so people with a milk allergy should avoid it.
What you could do: If you are a heavy trainer curious about colostrum, it is low risk to try, but sleep, diet and vaccines are surer ways to support immunity.
Sources: Marchbank et al. Am J Physiol Gastrointest Liver Physiol 2011 · Jones et al. BMC Sports Sci Med Rehabil 2016 · Aitkenhead et al. Nutrients 2025 · Aitkenhead et al. Nutrients 2025 (full text) · Oswal et al. J Pediatr Gastroenterol Nutr 2025
The full check, with quotes from each study
Not provenTrials and observed
What you hear: “A ketogenic diet is the single healthiest way to eat and will help you live longer.”
Keto may trim a little extra weight, but it's not proven to extend life, and it often raises LDL cholesterol.
What the studies found
A pooled analysis of 13 trials lasting at least a year found people on a very low-carb ketogenic diet lost about 0.9 kg more than those on a low-fat diet, with lower triglycerides and higher HDL but also higher LDL ('bad') cholesterol. In a 12-week crossover trial in 33 people with prediabetes or type 2 diabetes, keto and a Mediterranean-style diet gave similar blood sugar control, but LDL rose about 10% on keto versus a 5% fall on the Mediterranean diet, and keto was harder to stick with. No trial has tested whether keto helps people live longer. In observational data covering 432,179 people, eating under 40% of calories from carbs went with a 20% higher death rate than moderate intake, and low-carb eating based on animal foods looked worse than plant-based versions; this is a link, not proof of cause.
Take care: Keto can raise LDL cholesterol substantially in some people; people taking diabetes or blood pressure medicines, or who are pregnant, should only try it with medical supervision.
What you could do: If low-carb suits you, build it on vegetables, nuts, olive oil and fish, and have your cholesterol checked after a few months.
See it in the habit library, with what it means for your score
Sources: Bueno et al. Br J Nutr 2013 · Bueno et al. Br J Nutr 2013 · Gardner et al. Am J Clin Nutr 2022 (Keto-Med) · Seidelmann et al. Lancet Public Health 2018 · Seidelmann et al. Lancet Public Health 2018
The full check, with quotes from each study
Not provenNo trials
What you hear: “Drinking 16 ounces of straight celery juice every morning on an empty stomach heals chronic illnesses.”
No trials test celery juice for chronic illness; there's one case report and small celery extract studies.
What the studies found
We found no clinical trials testing celery juice as a treatment for chronic illness. A 2025 pooled analysis of 10 small randomised trials (511 people) found celery preparations lowered blood pressure, fasting blood sugar and triglycerides, but results varied widely between trials, and celery seed products or concentrated doses over 1,000 mg a day worked better than other celery preparations. The only published report on celery juice itself that we found describes a single 74-year-old man whose blood pressure fell over six months while also receiving other care, which cannot show cause and effect. Celery is a healthy vegetable, but the 'heals chronic illness' claim has no direct support.
Take care: The main risk is using juice in place of proven treatment for a chronic condition; juicing also removes most of the fibre in whole celery.
What you could do: Enjoy celery or its juice if you like it, but keep it alongside, not instead of, treatment your clinician recommends.
Sources: Liu et al. Front Nutr 2025 · Liu et al. Front Nutr 2025 · Liu et al. Front Nutr 2025 · Illes, J Chiropr Med 2021 (case report)
The full check, with quotes from each study
Not provenNo trials
What you hear: “Beef tallow is the best natural moisturizer and works better than modern skincare products.”
No human trials compare tallow with regular moisturizers; claims rest on anecdotes and ingredient theory.
What the studies found
A 2024 scoping review found only 19 relevant studies on tallow and skin, mostly lab and animal work, and noted that most published evidence lacks human subjects. A 2025 analysis of tallow skincare posts on YouTube, Instagram and TikTok found claims about acne, eczema and psoriasis rarely cited evidence, many posters had a financial interest, and the authors concluded the evidence is insufficient. Tallow is a fat that can sit on the skin like other rich moisturizers, but we found no trial comparing it with standard products. Dermatologists' general advice for dry skin is a fragrance-free cream or ointment with proven ingredients such as petrolatum, glycerin, dimethicone, shea butter or lanolin.
Take care: Side effects of putting tallow on human skin haven't been well studied; homemade or unrefined products may be less consistent, so patch-test first and stop if you get spots or irritation.
What you could do: If you like tallow balm, patch-test it; for eczema or very dry skin, a proven fragrance-free cream or ointment is the safer bet.
Sources: Russell et al. Cureus 2024 · Russell et al. Cureus 2024 (full text) · Almatroud et al. J Cosmet Dermatol 2025 · Almatroud et al. J Cosmet Dermatol 2025 · American Academy of Dermatology, tips to relieve dry skin
The full check, with quotes from each study
Not provenObserved
What you hear: “Sessions in a hyperbaric oxygen chamber reverse aging by lengthening your telomeres.”
One small study with no comparison group found longer telomeres in blood cells; that is not shown to slow aging.
What the studies found
The claim traces mainly to a 2020 study of 35 healthy adults aged 64 and over who had 60 daily chamber sessions; afterwards, telomeres in several types of white blood cell were over 20% longer and some markers of worn-out immune cells fell. There was no comparison group, so the changes can't be firmly credited to the chamber, and telomere length in blood cells is a lab marker, not proof of slower aging or longer life. We found no controlled trial showing hyperbaric oxygen slows aging or extends life. The FDA has cleared hyperbaric oxygen for several specific medical conditions and has warned about clinics promoting it for uses it has not cleared.
Take care: Pressurised oxygen can injure the middle ear and, less often, cause a collapsed lung or seizures, and oxygen-rich chambers raise the risk of fire.
What you could do: Save hyperbaric oxygen for conditions a doctor treats with it; for healthy aging, proven habits like exercise and good sleep are a better use of time and money.
Sources: Hachmo et al. Aging (Albany NY) 2020 · Hachmo et al. Aging (Albany NY) 2020 · US FDA consumer bulletin 2021 · US FDA consumer bulletin 2021 · Mayo Clinic: Hyperbaric oxygen therapy
The full check, with quotes from each study
Not provenAnimal studies
What you hear: “Injecting the peptide BPC-157 makes injuries like torn tendons heal dramatically faster.”
Healing results come almost entirely from animal studies; there are no proper human trials, and safety is unknown.
What the studies found
A 2025 systematic review found 36 relevant studies: 35 in animals or cells and just 1 in people. In animals, BPC-157 improved healing of muscle, tendon, ligament and bone injuries. The single human study was a look-back report in which 7 of 12 people injected in the knee for chronic knee pain said they had relief for more than 6 months, with no comparison group. Another review counted only three small human pilot studies in total and called it investigational. The FDA says it lacks enough information to know whether BPC-157 causes harm in people; in July 2026 an FDA advisory panel recommended allowing it in pharmacy compounding, but that advice is non-binding and is not a drug approval.
Take care: It is not an approved drug; products sold online are unregulated, and the FDA flags possible immune reactions and impurity problems. It is banned in sport at all times.
What you could do: For an injury, stick with proven care such as rest, physiotherapy and gradual loading, and treat BPC-157 as experimental.
Sources: Vasireddi et al. HSS J 2025 · Vasireddi et al. HSS J 2025 · McGuire et al. Curr Rev Musculoskelet Med 2025 · American Med Spa Association: FDA advisory committee recommends adding BPC-157 to compounding list · US FDA: Safety risks of certain bulk drug substances for compounding · German Sport University Cologne: WADA class S0
The full check, with quotes from each study
Not provenTrials and observed
What you hear: “The diabetes drug metformin slows aging, so everyone should be taking it.”
No trial shows it slows aging in the healthy; early survival data didn't hold up, and it can blunt exercise gains.
What the studies found
The idea grew from a 2014 UK records study in which people with diabetes who started metformin lived slightly longer than matched people without diabetes. A Danish registry study, including twin pairs, did not confirm this: after adjustments, people starting metformin had about a 32% higher death rate than people without diabetes. These are observed links in people with diabetes, not trials in healthy people. In randomised trials in older adults without diabetes, metformin reduced the muscle gained from 14 weeks of strength training and dulled the fitness gains from 12 weeks of aerobic training. TAME, a planned trial of over 3,000 people aged 65 to 79 meant to test metformin against aging, is still raising funds to launch.
Take care: Metformin is a prescription drug; in trials of older adults without diabetes it blunted the benefits of strength and aerobic training, so it shouldn't be taken for aging without a doctor's advice.
What you could do: If you want the benefits people hope metformin gives, regular exercise and strength training have far stronger evidence; ask a doctor before any off-label drug.
Sources: Bannister et al. Diabetes Obes Metab 2014 · Keys et al. Int J Epidemiol 2022 · Walton et al. Aging Cell 2019 (MASTERS) · Konopka et al. Aging Cell 2019 · American Federation for Aging Research: The TAME Trial
The full check, with quotes from each study
Doesn't hold upTrials and observed
What you hear: “Canola, sunflower and soybean oils are toxic, cause inflammation and heart disease, and you should cook with butter or tallow instead.”
These oils don't raise inflammation in trials, and cutting saturated fat, often for these oils, cut heart events.
What the studies found
A review of 15 randomised trials in healthy people found that adding linoleic acid, the main fat in these oils, did not raise any measured inflammation marker. A Cochrane review of 15 trials (about 56,700 people) found cutting saturated fat, often by replacing it with these oils, lowered combined heart events by 17% over at least two years, though deaths did not change. In 221,054 US adults, the biggest butter eaters had a 15% higher death rate than the smallest, while more plant oil went with lower death rates (an observed link). One recovered 1970s trial did not find fewer deaths with corn oil, so the heart benefit is debated, but not the 'toxic' claim.
What you could do: Using liquid plant oils in place of butter or lard is a reasonable, well-supported swap.
See it in the habit library, with what it means for your score
Sources: Johnson & Fritsche, J Acad Nutr Diet 2012 · Hooper et al. Cochrane Database Syst Rev 2020 · Zhang et al. JAMA Intern Med 2025 · Zhang et al. JAMA Intern Med 2025 · Marklund et al. Circulation 2019 · Ramsden et al. BMJ 2016
The full check, with quotes from each study
Doesn't hold upTrials and observed
What you hear: “Raw, unpasteurised milk is more nutritious than pasteurised milk and helps with allergies and lactose intolerance.”
Pasteurising barely changes nutrition, raw milk didn't ease lactose intolerance, and it causes more outbreaks.
What the studies found
A systematic review found pasteurisation lowers some vitamins, but the effect on milk's nutritional value is minimal because those vitamins are low in milk anyway. In a small randomised trial of 16 lactose-intolerant adults, raw milk did not reduce symptoms compared with pasteurised milk. Per amount drunk, unpasteurised dairy caused about 150 times more outbreaks in the US; a lower allergy rate in farm children is an observed link that may come from farm life itself.
Take care: Raw milk can carry germs that cause serious illness, and outbreaks fall hardest on children and teens.
What you could do: Choose pasteurised milk, especially for children, older adults, pregnant women and anyone with weak immunity.
Sources: Macdonald et al. J Food Prot 2011 · Mummah et al. Ann Fam Med 2014 · Langer et al. Emerg Infect Dis 2012 · Koski et al. Epidemiol Infect 2022
The full check, with quotes from each study
Doesn't hold upTrials and observed
What you hear: “Alkaline water and an alkaline diet change your body's pH and help prevent or fight disease, including cancer.”
Food and water change urine pH, not blood pH, and no trials show alkaline diets prevent cancer or bone loss.
What the studies found
Studies show diet can change the pH of urine but not of blood, which the body keeps in a narrow range. A systematic review screened 8,278 papers on diet acidity, alkaline water and cancer, found no randomised trials and only one usable study, which showed no link with bladder cancer. A review of 22 randomised trials and other studies on bone found no evidence that an alkaline diet protects bones.
What you could do: Plain water is fine; the vegetables and fruit in 'alkaline' diets are good for you for other reasons, not because of pH.
See it in the habit library, with what it means for your score
Sources: Fenton & Huang, BMJ Open 2016 · Fenton & Huang, BMJ Open 2016 (full text) · Fenton et al. Nutr J 2011
The full check, with quotes from each study
Doesn't hold upObserved
What you hear: “A glass of red wine a day is good for your heart.”
Once study flaws are corrected, light drinkers show no advantage; genetic studies show no heart protection.
What the studies found
Pooling 107 cohort studies of about 4.8 million people and correcting for flaws such as counting ex-drinkers as non-drinkers, low-volume drinkers (up to about 2 drinks a day) had no significantly lower death rate than lifelong non-drinkers (relative risk 0.93, not significant). A genetic study of 371,463 UK adults found the apparent heart benefit of light drinking faded after accounting for healthier lifestyles, and genetically higher drinking went with more high blood pressure and coronary disease. Both are observational, but the genetic method is designed to get closer to cause. Neither study looked at red wine separately, and no trial has tested wine against heart attacks.
Take care: Genetic analysis linked drinking of all amounts to higher heart risk, rising sharply at heavier intake, and risk of death rose clearly from about 3 drinks a day.
What you could do: If you enjoy wine, keep it light, but do not start drinking for your heart.
See it in the habit library, with what it means for your score
Sources: Zhao et al. JAMA Netw Open 2023 · Biddinger et al. JAMA Netw Open 2022
The full check, with quotes from each study
Doesn't hold upTrials
What you hear: “Everyone should take 5,000 to 10,000 IU of vitamin D a day because it prevents cancer, heart disease, infections and depression.”
Huge trials in mostly healthy adults found no fewer cancers, heart attacks, infections or cases of depression.
What the studies found
The VITAL trial gave 25,871 US adults 2,000 IU a day or a dummy pill for about 5 years and found no drop in cancer (hazard ratio 0.96) or major heart events (0.97). In the same trial, 18,353 people were tracked for depression, with no difference between groups (0.97). Australia's D-Health trial gave 21,315 people over 60 a monthly 60,000 IU dose and saw no fewer deaths (1.04). A 2025 pooled analysis of 40 trials (61,589 people) found no clear protection against chest and throat infections (odds ratio 0.94, not statistically significant). One small bright spot: in a pooled analysis of trials, daily (not monthly) doses went with 12% fewer cancer deaths, though the overall result across all trials was not significant. The Endocrine Society now advises against taking more than the standard daily amount to prevent disease in healthy adults under 75. Note that these trials used 2,000 IU a day or monthly doses; no large trial has tested 5,000 to 10,000 IU a day for disease prevention.
Take care: Big doses can backfire: in 2,256 older women, one yearly 500,000 IU dose led to 15% more falls and 26% more fractures, and 10,000 IU a day for 3 years slightly lowered bone density compared with 400 IU.
What you could do: Take vitamin D if you are low, older than 75, pregnant or advised by your doctor, at standard doses rather than megadoses.
See it in the habit library, with what it means for your score
Sources: Manson et al. N Engl J Med 2019 (VITAL) · Okereke et al. JAMA 2020 (VITAL-DEP) · Neale et al. Lancet Diabetes Endocrinol 2022 (D-Health) · Jolliffe et al. Lancet Diabetes Endocrinol 2025 · Sanders et al. JAMA 2010 · Kuznia et al. Ageing Res Rev 2023 · Demay et al. J Clin Endocrinol Metab 2024 (Endocrine Society guideline) · Burt et al. JAMA 2019
The full check, with quotes from each study
Doesn't hold upObserved
What you hear: “Everyone has to drink eight glasses of water daily, and most people walk around chronically dehydrated.”
No study backs a fixed 8 glasses; food and all drinks count, and thirst guides most healthy people well.
What the studies found
A 2002 review that went looking for the source of the '8 x 8' rule found no scientific studies supporting it. The US National Academies set adequate intakes of about 2.7 litres a day for women and 3.7 litres for men, but that is total water from all drinks and food, with roughly 20% coming from food, and they said most healthy people meet their needs by drinking to thirst. A 2022 study that tracked water use with isotopes in 5,604 people from 23 countries found needs vary widely with body size, activity, climate and age, and concluded the 8-glass (about 2 litre) advice is not backed by objective evidence. Some surveys using blood and urine tests label many middle-aged and older adults as under-hydrated, but these show links, not proof that drinking more improves health, and they don't support one fixed amount for everyone.
Take care: People who exercise hard, work in heat, are pregnant or breastfeeding, or have certain medical conditions may need more fluid; anyone told by a doctor to limit fluids should follow that advice.
What you could do: Drink when you're thirsty, count tea, coffee and watery foods, and drink more in heat or during hard exercise.
See it in the habit library, with what it means for your score
Sources: Valtin, Am J Physiol Regul Integr Comp Physiol 2002 · National Academies (Institute of Medicine) news release 2004 · National Academies (Institute of Medicine) news release 2004 · Yamada et al. Science 2022 · Yamada et al. Science 2022 (full text)
The full check, with quotes from each study
Doesn't hold upTrials
What you hear: “Breakfast is the most important meal, and skipping it slows your metabolism and makes you put on weight.”
In trials, skipping breakfast didn't cause weight gain or slow metabolism; breakfast eaters ate a bit more overall.
What the studies found
A 2019 review of 13 randomised trials found that, in the 7 that measured weight, people assigned to eat breakfast weighed about 0.44 kg more than those told to skip it, and in 10 trials they ate about 260 more calories a day, though the trials were short and of mostly low quality. A 16-week trial of 309 adults trying to lose weight found that being told to eat or skip breakfast made no real difference to weight loss. A 6-week trial in 33 lean adults found that eating or skipping breakfast did not change resting metabolism. Observational studies do find that breakfast skippers are more likely to be overweight (45 studies, about 1.4 to 1.5 times the odds), but skippers differ in many other habits, and the trials don't show breakfast itself prevents weight gain.
Take care: People on insulin or other glucose-lowering medicines should talk to their clinician before changing meal timing.
What you could do: Eat breakfast if it keeps you full and focused, skip it if you're not hungry; total diet quality matters more.
See it in the habit library, with what it means for your score
Sources: Sievert et al. BMJ 2019 · Sievert et al. BMJ 2019 · Dhurandhar et al. Am J Clin Nutr 2014 · Betts et al. Am J Clin Nutr 2014 · Ma et al. Obes Res Clin Pract 2020
The full check, with quotes from each study
Doesn't hold upTrials
What you hear: “Ten minutes standing on a vibration plate equals an hour of exercise and melts body fat.”
Trials found vibration plates alone don't cut weight or fat; they may give small bone gains at some spots.
What the studies found
A 2025 pooled analysis of 20 randomised trials (585 people) found that vibration training on its own did not change body weight, BMI or fat mass compared with control groups. A 2026 pooled analysis of 14 trials (1,447 older adults) comparing vibration training with conventional exercise found small extra gains in bone density at some hip and lower-spine spots, but no difference in total hip density, and most of the trials had some quality concerns. We found no study showing that 10 minutes on a plate matches an hour of exercise; the weight-loss trials point the other way.
What you could do: Treat a vibration plate as an optional extra at most; walking, strength work and diet do the real work for weight and bones.
Sources: Gou et al. Int J Obes 2025 · Gou et al. Int J Obes 2025 · Chen et al. BMC Musculoskelet Disord 2026 · Chen et al. BMC Musculoskelet Disord 2026
The full check, with quotes from each study
Doesn't hold upObserved
What you hear: “Tiredness, brain fog and belly fat are caused by 'adrenal fatigue', which you fix with adrenal support supplements.”
'Adrenal fatigue' isn't a recognised condition, and tested 'adrenal support' pills contained real hormones.
What the studies found
A 2016 systematic review screened 3,470 articles and examined 58 studies of cortisol and fatigue; results conflicted, and it concluded there is no evidence that 'adrenal fatigue' is an actual medical condition. The Endocrine Society says no scientific proof supports it and no test can detect it. When US researchers tested 12 over-the-counter 'adrenal support' supplements, every one contained some thyroid hormone and most contained at least one steroid hormone, which the authors called hidden ingredients. The symptoms people describe are real and worth checking with a doctor, but this label doesn't explain them.
Take care: The Endocrine Society warns that taking adrenal hormones you don't need can make your own adrenal glands stop working, risking a life-threatening adrenal crisis when you stop.
What you could do: If you're tired, foggy or gaining weight around the middle, see a doctor to check for real causes, and skip 'adrenal support' pills.
Sources: Cadegiani & Kater, BMC Endocr Disord 2016 · Cadegiani & Kater, BMC Endocr Disord 2016 · Endocrine Society: Adrenal fatigue · Akturk et al. Mayo Clin Proc 2018 · Endocrine Society: Adrenal fatigue
The full check, with quotes from each study
