Is Obesity a Willpower Problem? The Biology of Weight, Diets, and GLP-1s

Obesity roughly tripled in about 60 years, and the genes didn't change in that time. So if body weight isn't a willpower problem, what is it? Dr. Jordan Feigenbaum and Dr. Austin Baraki walk through what actually sets your weight: the adoption and twin studies behind the genetics, the "defended range" your biology fights to hold, the food environment that does most of the eating for you, and where GLP-1 medications actually work. Along the way — why diets regain after you white-knuckle them, what The Biggest Loser six-year data show about resting metabolism, and four willpower myths worth retiring.
Hosted by Dr. Jordan Feigenbaum and Dr. Austin Baraki, co-founders of Barbell Medicine.
Timestamps
00:00 Cold open: Danny Cahill and The Biggest Loser
01:03 What we mean by "willpower"
05:48 Obesity tripled in ~60 years: the one number
06:31 Adoption and twin studies: genes vs. household
09:37 Set point vs. the defended range
10:37 Gene–environment mismatch
14:03 In the clinic: a lifelong weight history
19:18 Losing weight vs. keeping it off
20:26 Appetite doesn't reset (Sumithran)
25:52 Metabolic adaptation and the Biggest Loser data
34:07 Part 2: eating on autopilot
35:10 Portion size runs the meal
39:12 What changed in the food supply
40:42 Same genes, new environment: Pima and immigrants
43:20 Why ultra-processed food is easy to overeat
50:28 Processing vs. calories: the Hall ward study
52:36 When the brain changes eating: gourmand syndrome
1:00:01 Why the willpower story stuck
1:01:08 Taft, Churchill, and the intelligence myth
1:02:43 Does intelligence predict weight? (sibling study)
1:11:16 Are GLP-1s cheating? What they actually do
1:15:10 Beyond the scale: muscle, health, nutrition
1:24:21 Myth-busting: lightning round
1:39:04 Three takeaways: what to actually do
1:41:00 Danny Cahill, revisited
Resources
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Prevalence of Overweight, Obesity, and Severe Obesity Among Adults Age 20 and Older: United States, 1960-1962 Through August 2021-August 2023. NCHS Health E-Stats. 2024. https://www.cdc.gov/nchs/data/hestat/hestat111.htm
Obesity and Severe Obesity Prevalence in Adults: United States, August 2021-August 2023. NCHS Data Brief No. 508. Hyattsville, MD: National Center for Health Statistics; 2024. https://www.cdc.gov/nchs/products/databriefs/db508.htm
Hill JO, Peters JC. Environmental contributions to the obesity epidemic. Science. 1998;280(5368):1371-1374. https://doi.org/10.1126/science.280.5368.1371
Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. https://doi.org/10.1136/bjsports-2017-097608
Stunkard AJ, Sorensen TIA, Hanis C, et al. An adoption study of human obesity. N Engl J Med. 1986;314(4):193-198. https://doi.org/10.1056/NEJM198601233140401
Stunkard AJ, Harris JR, Pedersen NL, McClearn GE. The body-mass index of twins who have been reared apart. N Engl J Med. 1990;322(21):1483-1487. https://doi.org/10.1056/NEJM199005243222102
Speakman JR, Levitsky DA, Allison DB, et al. Set points, settling points and some alternative models: theoretical options to understand how genes and environments combine to regulate body adiposity. Dis Model Mech. 2011;4(6):733-745. https://doi.org/10.1242/dmm.008698
Kalm LM, Semba RD. They starved so that others be better fed: remembering Ancel Keys and the Minnesota Experiment. J Nutr. 2005;135(6):1347-1352. https://doi.org/10.1093/jn/135.6.1347
Sumithran P, Prendergast LA, Delbridge E, et al. Long-term persistence of hormo...