The claimEvidence A · guideline-tier
I can't lose weight because my metabolism is slow
The evidence
Lichtman 1992 NEJM: self-reported 'diet-resistant' adults underestimate intake by ~47% and overstate exercise by ~51%. Individual RMR varies only ±200 kcal — far smaller than the reporting bias.
The mechanism, in brief
Almost everyone who diets seriously hits the same wall around week 4-8: the scale stops moving. You're still weighing food, you haven't skipped a workout, but the number just won't budge — sometimes it even ticks up.
Sources (2)
- Fothergill, E., Guo, J., Howard, L., Kerns, J. C., Knuth, N. D., Brychta, R., Chen, K. Y., Skarulis, M. C., Walter, M., Walter, P. J., & Hall, K. D. (2016). Persistent metabolic adaptation 6 years after 'The Biggest Loser' competition. Obesity, 24(8), 1612–1619.
- Rosenbaum, M., & Leibel, R. L. (2010). Adaptive thermogenesis in humans. International Journal of Obesity, 34(Suppl 1), S47–S55.