Popular claims, checked against the studies

Every named diet that works, works for one reason: it makes you eat less energy than you spend. Below are the claims we hear most, what the studies actually found, and a short checklist for judging the next one you come across. Each verdict links to its study.

01 · The verdicts

Claim	What the evidence shows	Verdict
"Eat small, frequent meals to boost your metabolism."	With calories equal, two meals of 1,000 kcal and eight of 250 kcal lose the same fat. Big meals store more after eating and burn more in the long gap; small meals store less each time and never get a long burning window. Net difference: zero. For keeping muscle, 3 to 5 protein-containing meals a day is the sensible range.	False (Cameron 2010, Ohkawara 2013, Atherton 2010)
"Carbs make you fat; it's the insulin."	In metabolic-ward studies with calories and protein matched, a ketogenic diet and a diet with over 300 g of carbs a day lost the same fat; across 32 controlled feeding studies the lower-fat diets lost slightly more (about 16 g a day). Insulin explains 1 to 10% of the variation in BMI. Overfed women turned only 1.4% of their carbohydrate into fat; the fat they gained came from dietary fat.	False (Hall 2016, Hall & Guo 2017, Mendelian randomisation 2018, overfeeding study)
"Sugar is uniquely fattening."	Six weeks, all meals provided, 4% vs 43% of calories from sugar at equal calories, protein and fat: both groups lost just over 7 kg with the same improvements in health markers. Sugar matters when it drives you to eat more, which it easily does.	False at equal calories (Surwit 1997)
"Fasting / eating windows burn more fat."	Intermittent fasting and time-restricted eating produce the same fat loss, adherence and heart-health markers as continuous restriction when calories are matched. Useful if a window helps you eat less; watch protein, and the 23:1 "binge window".	No advantage (Seimon 2015, Trepanowski 2017)
"Don't eat carbs at night."	Timing matters little next to the total. Where late eating hurts, it is because late eating adds calories.	Not supported (Kinsey & Ormsbee 2015)
"Keto is superior for fat loss."	Not when calories and protein are matched. It is a legitimate way to eat less for people who like it; ketones cannot fuel hard anaerobic training, adherence is the usual problem, and regain is common when carbs return.	Equal, not superior (Hall 2016, meta-analysis 2018)
"Clean calories don't count the same."	A calorie is a unit of energy; the foods differ, the calories do not. Nutrient-dense, low-calorie foods win on satiety and micronutrients, which is why we build meals around them, not because their energy is different. A coconut-oil, nut-butter, "clean" meal can still be 1,000 kcal.	False, but the foods still matter
"High protein harms kidneys and bones."	No study shows protein damaging a healthy kidney or liver, including a year at high intakes. Protein raises calcium excretion but also calcium absorption; with adequate calcium it is favourable to bone. Higher protein improves blood lipids, blood pressure and inflammation when calories are controlled.	Not in healthy adults (Antonio 2016, Shams-White 2017, Martin 2005)
"Detox teas and cleanses remove toxins."	A critical review found no commercial detox that names the toxins it removes or shows that it removes them, and no evidence for weight management. They "work" by cutting alcohol, processed food and calories for a week.	No evidence (Klein & Kiat 2015)
"Alkaline foods protect your bones."	Blood pH is held at 7.35 to 7.45 whatever you eat; urine pH is not blood pH and does not predict bone loss over five years. The real benefit of "alkaline" eating is more fruit and vegetables.	No evidence for the mechanism (Schwalfenberg 2012, Fenton 2010)
"Eat for your blood type."	A systematic review found no study supporting health benefits from blood-type diets.	No evidence (Cusack 2013)
"Cut dairy to lose fat."	Dairy consumers show better bone density, more lean mass and less body fat in controlled trials; milk protein supports muscle building. No reason to exclude it unless you are intolerant or allergic.	Not supported (Josse 2012, Phillips 2009)
"My metabolism is damaged / in starvation mode."	Metabolic adaptation is real: resting energy about 15% below prediction, hundreds of kcal less unconscious movement, lasting years in extreme cases. It is not a reason weight cannot be lost; it means the deficit has to be re-established from a lower maintenance, or, if you are far below prediction, rebuilt first. In the famous "I can't lose on 1,200 kcal" study, intake was under-reported by 47%.	Half true (Rosenbaum 2008, Fothergill 2016, Lichtman 1992)
"A diet break or refeed speeds up fat loss."	Refeeds raise leptin briefly but have not been shown to speed fat loss; the weekly deficit is what counts. Maintenance breaks of two weeks every two weeks did improve loss per deficit week and protect resting energy over 30 weeks in one trial. Both are adherence tools, used when they help you keep going.	Breaks: supported; refeeds: adherence only (Byrne 2018, Harvie 2011)

02 · Why every one of them "works" for a while

Each of them narrows what you can eat (foods, macros or hours), and narrowing is restriction. Restriction creates the deficit; the deficit does the fat loss. The question that matters is not "does it work" but "can I still be doing it a year from now": the plan that needs the least willpower is the one that survives a bad week at work. If you hate how you eat, you will stop, and the regain mechanics take over.

Our rules, distilled: do not ban foods you can control; never ban nutrient-dense foods you like; accept deviations (weddings exist) and look forward, not back; track, at least for a while, to learn the skill; protein and fibre first; the rest is preference.

03 · Is this diet or product nonsense? A checklist

Is there a plan for afterwards? A diet without a phase-after-the-phase is a regain plan.
Does it rely on heavy restriction or fasting? Extreme restriction produces fast results and the strongest biological rebound.
Does it promise more than 1% of bodyweight a week? "15 lb in a week" is water and muscle. 0.4 to 0.8% a week keeps the muscle.
Does it cost a lot, or sell a product it cannot explain? Ask which toxins a detox removes, or which mechanism a fat burner uses, and how much.
Does it name the studies? Independent confirmation, numbers rather than adjectives, and a claim that could in principle be proven wrong are the marks of something real. Arguments from authority, including from us, carry little weight on their own; the links do.
Search "[name] scam". Takes a minute.

Honest coaching cannot always give exact time frames, does not promise magic, and aims to make you not need it. If a method promises the opposite, that is the tell.

Studies

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