Evidence Base

The studies behind every answer.

Original papers. Full analysis. Every finding linked to its DOI so you can check our work.

The Number Your App Cannot See The equation behind MyFitnessPal was built to replace math calibrated on 1919 bodies. It explains 71% of your metabolism. The researchers tried everything to crack the other 29%. MD et al. · 1990 · The American Journal of Clinical Nutrition · n=498

1,053 Calories Your Diary Cannot See Scientists used nuclear water to track every calorie for 14 days. The gap between what these dieters reported and what they actually ate explains why the scale never moved. SW et al. · 1992 · New England Journal of Medicine · n=10

What Biggest Loser Did to Their Metabolism Fourteen contestants lost massive weight on The Biggest Loser. Six years later, their resting metabolism was still burning 499 fewer calories per day — and the contestants who kept the most weight off had it worst. Fothergill et al. · 2016 · Obesity · n=14

14,600 days of stable metabolism — the age-30 crash never happened The largest metabolic database ever assembled shows your metabolism holds from 20 to 60. The real decline starts 33 years later than the myth claims, and it is cellular. P et al. · 2021 · Science · n=6,421

Your Apple Watch calorie count is 28% wrong A 56-study meta-analysis found the Apple Watch overestimates calories by 28 percent while getting heart rate and steps right. No brand does better. Kang et al. · 2025 · Physiological Measurement · n=56

Metabolism Scored Zero. Fidgeting Scored 77. Sixteen people ate the same extra food for eight weeks. The study found that resting metabolism had zero predictive power over who gained fat. A type of movement nobody was tracking predicted nearly everything. Levine et al. · 1999 · Science · n=16

Your Body Charges a Tax on Every Gram of Protein A meta-analysis of 52 studies measured exactly how many extra calories your body burns digesting protein. The number is bigger than most people think, but the boost works differently than the fitness industry promises. LL et al. · 2024 · Advances in Nutrition · n=1,232

You Burn What a Wolf Your Size Burns Isotope-labeled water tracked 647 people over two decades. What researchers found about activity, obesity, and wild mammals challenges every 'sitting is the new smoking' headline. KR et al. · 2013 · Frontiers in Physiology · n=647

Studies

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