Up Two Kilos After a Big Weekend? Why Most of It Isn't Fat

The discussion centers on the common misconception regarding weight gain and fat accumulation, particularly the belief that a sudden increase in scale weight directly correlates to fat gain. The speaker addresses frequent concerns from clients who report significant weight fluctuations after weekends of indulgence, emphasizing that such changes are often due to factors like water retention and glycogen storage rather than actual fat gain.

The speaker explains the historical context of the widely cited figure of 3,500 calories per pound of body weight, which originated from a 1958 study. While this number provides a rough estimate for energy content in fat tissue, it does not accurately reflect the complexities of weight gain and loss. Factors such as individual metabolism, the type of calories consumed, and the body's adaptive responses play significant roles in how weight changes occur. The speaker highlights that weight gain can result from a mix of fat, water, glycogen, and other factors, making it essential to understand that not all weight fluctuations indicate fat accumulation.

Ultimately, the speaker encourages a more nuanced approach to interpreting scale readings, suggesting that individuals focus on long-term habits rather than short-term fluctuations. By doing so, they can avoid unnecessary panic and make informed decisions about their health and nutrition.

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Episode Summary In this solo Monday episode, Mikki tackles a question she gets constantly from clients and on social media: why the scales can jump two kilos after a big weekend when that much fat gain seems impossible. She traces the familiar rule that a kilo of fat is worth about 7,700 calories (3,500 per pound) back to Wishnofsky's 1958 paper. She explains why it is a reasonable estimate of the energy stored in mostly-fat body weight, but a poor prediction of how much fat a given surplus will add. Using overfeeding studies, including the Levine NEAT study and the Bouchard identical twin study, Mikki works through three problems with the rule: extra food isn't all stored, not all weight gain is fat, and energy balance shifts as your body changes. She then reruns the maths on a genuinely big weekend and shows why a Monday-morning jump is mostly glycogen, water, salt and food in transit. That understanding should change what you do next. Key Topics Where the 7,700 calorie (3,500 kcal per pound) rule came from, and why it is defensible as an estimate of the energy in a kilo of mostly-fat body weight The difference between a kilo of pure lipid, a kilo of adipose tissue and a kilo on the scales, which can represent anything from about 1,000 to more than 9,000 calories Why digesting and storing food costs energy, and why a carbohydrate surplus is stored a little less efficiently than a fat surplus without meaning carbs cause more fat gain What extra protein changes during overfeeding: in a metabolic ward study fat gain was similar across protein intakes, but higher-protein diets added lean tissue and raised resting energy expenditure How NEAT (non-exercise activity thermogenesis) explained much of the tenfold difference in fat storage between people eating the same surplus The identical twin overfeeding study: about 11 kg predicted by the rule, 8.1 kg gained on average, with a range of 4.3 to 13.3 kg and responses that clustered within twin pairs. Mikki notes that these were young men, and the results can't be mapped directly onto women in perimenopause How glycogen and water, sodium, alcohol and food in the gut drive short-term jumps on the scales, and why the water-to-glycogen ratio isn't as fixed as often stated Why energy balance isn't static, and why the energy content of each kilo lost is lower early in a diet and in leaner people Rerunning the maths: roughly 9,000–11,000 surplus calories to add a kilo of fat tissue, and around 400–500 g of fat at most from a 4,500 calorie weekend surplus Why the 7,700 rule creates false precision in both directions, from panic after a big weekend to disappointment after week one of a new plan Chapters 00:00 Introduction: the Monday morning weigh-in 02:52 Where the 7,700 calorie rule comes from 05:17 Why extra food isn't all stored 07:30 NEAT and the twin overfeeding study 10:29 Glycogen, water and short-term weight gain 13:00 Why energy balance isn't static 16:15 What a kilo on the scales really means 18:09 Big weekends, new diets and what to do next Guest / Resources Wishnofsky (1958), Caloric Equivalents of Gained or Lost Weight, American Journal of Clinical Nutrition Horton et al. (1995), Fat and carbohydrate overfeeding in humans: different effects on energy storage, American Journal of Clinical Nutrition Antonio et al. (2014), The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals, Journal of the International Society of Sports Nutrition Bray et al. (2012), Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating, JAMA Levine, Eberhardt and Jensen (1999), Role of nonexercise activity thermogenesis in resistance to fat gain in humans, Science Bouchard et al. (1990), The response to long-term overfeeding in identical twins, New England Journal of Medicine Ols