Evidence Base

The studies behind every answer.

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

Your Body Has a Calorie Ceiling — And Your Apple Watch Doesn't Know About It A study of 332 adults found that above moderate activity, more exercise didn't mean more calories burned. The data behind your body's invisible energy budget — and why it hits hardest on the people trying hardest to lose weight. Pontzer et al. · 2016 · Current Biology · n=332

The 1 kg Argument Thirty-six studies tried to settle the cardio-versus-weights debate for fat loss. The gap they found would fit on a kitchen scale — and when both sides did equal work, it vanished entirely. Lafontant et al. · 2025 · Journal of the International Society of Sports Nutrition · n=1,564

The Gym-Floor Myth That 43 Studies Couldn't Find The interference effect — the idea that cardio cancels out your strength gains — was tested across 43 studies and 1,090 people. The measured effect on muscle growth landed at one hundredth of a standard deviation. Schumann et al. · 2022 · Sports Medicine · n=1,090

The Afterburn: One Butter Pat Per Day Twenty-nine studies proved the afterburn effect is real. Then the scientists said it does not matter. The fat-loss advantage of HIIT over regular cardio is five grams per day — and the researchers who found it called it clinically meaningless. al. et al. · 2023 · International Journal of Environmental Research and Public Health · n=807

The Step Count Where Your Tracker Stops Being Right A 57-study review of 161,176 adults found exactly where step-count benefits flatten — and it's thousands of steps below the number your fitness app has been chasing. D et al. · 2025 · The Lancet Public Health · n=161

The Coin Flip That Ended the Zone 2 War Researchers pooled 23 studies on exercise intensity in older adults. The gap between going hard and going moderate came out smaller than the energy cost of standing up from a chair. Fosstveit et al. · 2024 · Scandinavian Journal of Medicine & Science in Sports · n=0

Studies

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