The claimEvidence B · meta-analysis
Obesity is genetic destiny — you can't change it
The evidence
Heritability is a population statistic, not a personal verdict. Genes give a tendency, not an endpoint; the same genome yields very different weights in different environments (Loos & Yeo 2022).
The mechanism, in brief
"Being heavy comes from laziness and greed" is wrong: individual differences in appetite, fullness and reward are partly written in the genes, and equating body weight with morality is neither scientific nor useful. "Genes decide everything, so effort is pointless" is wrong too: heritability is a population statistic,…
Sources (3)
- 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. 14 of the 16 original 'Biggest Loser' competitors re-measured 6 years later (DXA, indirect calorimetry). End of the 30-week competition: weight -58.3 kg, resting metabolic rate (RMR) -610 kcal/day. At 6 years: 41.0 kg regained, RMR still 704 kcal/day below baseline, and metabolic adaptation (RMR residual after adjusting for body composition and age) -499 ± 207 kcal/day. Regain was not correlated with metabolic adaptation at the competition's end (r = -0.1, P = 0.75), but those maintaining more weight loss at 6 years had greater concurrent metabolic slowing (r = 0.59, P = 0.025); the authors call adaptation a proportional but incomplete response to contemporaneous efforts to reduce weight (abstract, PMID 27136388).
- Sumithran, P., Prendergast, L. A., Delbridge, E., Purcell, K., Shulkes, A., Kriketos, A., & Proietto, J. (2011). Long-term persistence of hormonal adaptations to weight loss. The New England Journal of Medicine, 365(17), 1597–1604. 50 overweight or obese adults without diabetes on a 10-week very-low-energy diet; mean loss 13.5 kg. Measured at baseline, 10 and 62 weeks: leptin, ghrelin, PYY, GIP, GLP-1, amylin, pancreatic polypeptide, CCK, insulin and subjective appetite. At 62 weeks, leptin, PYY, CCK, insulin, ghrelin, GIP, pancreatic polypeptide and hunger still differed significantly from baseline; GLP-1 and amylin are not in that list. No thyroid hormone or energy-expenditure measure is reported in the abstract (abstract, PMID 22029981).
- Loos, R. J. F., & Yeo, G. S. H. (2022). The genetics of obesity: from discovery to biology. Nature Reviews Genetics, 23(2), 120-133. Polygenic (common) and monogenic (rare) obesity share genetic and biological underpinnings, pointing to a central role for the brain in body-weight control.