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.Timestamps00:00 Cold open: Danny Cahill and The Biggest Loser01:03 What we mean by "willpower"05:48 Obesity tripled in ~60 years: the one number06:31 Adoption and twin studies: genes vs. household09:37 Set point vs. the defended range10:37 Gene–environment mismatch14:03 In the clinic: a lifelong weight history19:18 Losing weight vs. keeping it off20:26 Appetite doesn't reset (Sumithran)25:52 Metabolic adaptation and the Biggest Loser data34:07 Part 2: eating on autopilot35:10 Portion size runs the meal39:12 What changed in the food supply40:42 Same genes, new environment: Pima and immigrants43:20 Why ultra-processed food is easy to overeat50:28 Processing vs. calories: the Hall ward study52:36 When the brain changes eating: gourmand syndrome1:00:01 Why the willpower story stuck1:01:08 Taft, Churchill, and the intelligence myth1:02:43 Does intelligence predict weight? (sibling study)1:11:16 Are GLP-1s cheating? What they actually do1:15:10 Beyond the scale: muscle, health, nutrition1:24:21 Myth-busting: lightning round1:39:04 Three takeaways: what to actually do1:41:00 Danny Cahill, revisited Resources Barbell Medicine coaching and templates: https://www.barbellmedicine.comhttps://www.barbellmedicine.com/shop/subscriptions/plus-podcast-subscription/https://www.barbellmedicine.com/shop/subscriptions/barbell-medicine-premium/Signal book pre-order: https://www.barbellmedicine.com/shop/learning/signal/Coaching, programs & templates: https://www.barbellmedicine.com/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.htmObesity 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.htmHill JO, Peters JC. Environmental contributions to the obesity epidemic. Science. 1998;280(5368):1371-1374. https://doi.org/10.1126/science.280.5368.1371Morton 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-2017-097608Stunkard 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/NEJM198601233140401Stunkard 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/NEJM199005243222102Speakman 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.008698Kalm 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/135.6.1347Sumithran P, Prendergast LA, Delbridge E, et al. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011;365(17):1597-1604. https://doi.org/10.1056/NEJMoa1105816Fothergill E, Guo J, Howard L, et al. Persistent metabolic adaptation 6 years after 'The Biggest Loser' competition. Obesity (Silver Spring). 2016;24(8):1612-1619. https://doi.org/10.1002/oby.21538Hall KD. Energy compensation and metabolic adaptation: 'The Biggest Loser' study reinterpreted. Obesity (Silver Spring). 2022;30(1):11-13. https://doi.org/10.1002/oby.23308Cohen DA, Farley TA. Eating as an automatic behavior. Prev Chronic Dis. 2008;5(1):A23. https://www.cdc.gov/pcd/issues/2008/jan/07_0046.htmRolls BJ, Morris EL, Roe LS. Portion size of food affects energy intake in normal-weight and overweight men and women. Am J Clin Nutr. 2002;76(6):1207-1213. https://doi.org/10.1093/ajcn/76.6.1207Diliberti N, Bordi PL, Conklin MT, Roe LS, Rolls BJ. Increased portion size leads to increased energy intake in a restaurant meal. Obes Res. 2004;12(3):562-568. https://doi.org/10.1038/oby.2004.64Hollands GJ, Shemilt I, Marteau TM, et al. Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. Cochrane Database Syst Rev. 2015;(9):CD011045. https://doi.org/10.1002/14651858.CD011045.pub2Hall KD, Ayuketah A, Brychta R, et al. Ultra-processed diets cause excess calorie intake and weight gain: an inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67-77.e3. https://doi.org/10.1016/j.cmet.2019.05.008Pontzer H, Raichlen DA, Wood BM, et al. Hunter-gatherer energetics and human obesity. PLoS One. 2012;7(7):e40503. https://doi.org/10.1371/journal.pone.0040503Careau V, Halsey LG, Pontzer H, et al. Energy compensation and adiposity in humans. Curr Biol. 2021;31(20):4659-4666.e2. https://doi.org/10.1016/j.cub.2021.08.016Miller WC, Koceja DM, Hamilton EJ. A meta-analysis of the past 25 years of weight loss research using diet, exercise or diet plus exercise intervention. Int J Obes Relat Metab Disord. 1997;21(10):941-947. https://doi.org/10.1038/sj.ijo.0800499Gaesser GA, Angadi SS. Obesity treatment: weight loss versus increasing fitness and physical activity for reducing health risks. iScience. 2021;24(10):102995. https://doi.org/10.1016/j.isci.2021.102995US Department of Agriculture, Economic Research Service. Food Availability (Per Capita) Data System, Loss-Adjusted Food Availability. https://www.ers.usda.gov/data-products/food-availability-per-capita-data-system/Steele EM, Baraldi LG, Louzada ML, Moubarac JC, Mozaffarian D, Monteiro CA. Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study. BMJ Open. 2016;6(3):e009892. https://doi.org/10.1136/bmjopen-2015-009892Wang L, Martinez Steele E, Du M, et al. Trends in consumption of ultraprocessed foods among US youths aged 2-19 years, 1999-2018. JAMA. 2021;326(6):519-530. https://doi.org/10.1001/jama.2021.10238Schulz LO, Bennett PH, Ravussin E, et al. Effects of traditional and western environments on prevalence of type 2 diabetes in Pima Indians in Mexico and the US. Diabetes Care. 2006;29(8):1866-1871. https://doi.org/10.2337/dc06-0138Goel MS, McCarthy EP, Phillips RS, Wee CC. Obesity among US immigrant subgroups by duration of residence. JAMA. 2004;292(23):2860-2867. https://doi.org/10.1001/jama.292.23.2860Papavramidou NS, Papavramidis ST, Christopoulou-Aletra H. Galen on obesity: etiology, effects, and treatment. World J Surg. 2004;28(6):631-635. https://doi.org/10.1007/s00268-004-7458-5Haslam DW, Haslam F. Fat, Gluttony and Sloth: Obesity in Literature, Art and Medicine. Liverpool: Liverpool University Press; 2009. https://www.liverpooluniversitypress.co.uk/9781846311734/fat-gluttony-and-sloth/Townend L. The moralizing of obesity: a new name for an old sin? Crit Soc Policy. 2009;29(2):171-190. https://doi.org/10.1177/0261018308101625Levine DI. Corpulence and correspondence: President William H. Taft and the medical management of obesity. Ann Intern Med. 2013;159(8):565-570. https://doi.org/10.7326/0003-4819-159-8-201310150-00012Wright L, Davies NM, Bann D. The association between cognitive ability and body mass index: a sibling-comparison analysis in four longitudinal studies. PLoS Med. 2023;20(4):e1004207. https://doi.org/10.1371/journal.pmed.1004207Mechanisms of GLP-1 receptor agonist-induced weight loss: a review of central and peripheral pathways. Am J Med. 2025 (review of hypothalamic arcuate nucleus and brainstem area postrema action). https://www.sciencedirect.com/science/article/pii/S0002934325000592Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002. https://doi.org/10.1056/NEJMoa2032183Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205-216. https://doi.org/10.1056/NEJMoa2206038Grannell A, Fallon F, Al-Najim W, le Roux C. Obesity and responsibility: is it time to rethink agency? Obes Rev. 2021;22(8):e13270. https://doi.org/10.1111/obr.13270Al Khatib HK, Harding SV, Darzi J, Pot GK. The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis. Eur J Clin Nutr. 2017;71(5):614-624. https://doi.org/10.1038/ejcn.2016.201Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. https://doi.org/10.1186/1550-2783-11-20Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. 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