The fasting-mimicking diet selectively reduces abdominal fat while sparing subcutaneous fat and preserving or increasing relative lean body mass following refeeding in humans and mice.
"and of course you lose abdominal fat because after a few days this becomes your reservoir. I mean, every—although all the—it doesn't touch subcutaneous fat for some reason, it only goes to the main depot that have this effect. So that's great news, but the muscle is also decreased. But then when you refeed, the muscle is rebuilt... and this, no effect on subcutaneous fat and no or very little effect on even absolute lean body mass. In fact, the relative lean body mass goes up." (said at 0:43:07)
Randomized trial data on periodic cycles of the fasting-mimicking diet (FMD) in humans (such as the 100-subject trial by Wei et al., 2017) show that 3 monthly cycles of FMD reduce trunk and total body fat while largely preserving absolute lean mass and increasing relative lean body mass after normal refeeding. However, stating that FMD has 'no effect on subcutaneous fat' or 'doesn't touch subcutaneous fat' is an exaggeration; while visceral/trunk fat is preferentially mobilized, overall body fat decreases as well.
Studies on yo-yo dieting and prolonged starvation periods show that they lower metabolic rate, which can lead to subsequent weight gain.
"there's famous papers that have shown what they call the yo-yo diets, right? They have shown that this can actually lower your metabolism if you have this prolonged starvation period. It can lower your metabolism, and then you tend to gain weight." (said at 0:39:57)
Prolonged severe caloric restriction or starvation induces adaptive thermogenesis—an acute reduction in resting energy expenditure beyond what is explained by loss of body mass. However, the speaker's claim that 'yo-yo dieting' (weight cycling) permanently depresses metabolic rate and drives subsequent weight gain is not supported by systematic evidence. Systematic reviews examining weight cycling find that the vast majority of studies show no adverse or permanent reduction in resting metabolic rate from repeated cycles of weight loss and regain. Furthermore, systematic reviews indicate that adaptive thermogenesis tends to attenuate during weight-stable maintenance.
- context: Does adaptive thermogenesis occur after weight loss in adults? A systematic review. (The British journal of nutrition 2022) · cited 41x in the literature
"These findings suggest that although WL may lead to AT in some of the EE components, these values may be small or non-statistically significant when higher-quality methodological designs are used. Furthermore, AT seems to be attenuated, or non-existent, after periods of weight stabilisation/neutral EB." (abstract, results, passage verified)
pubmedfull study (doi) - contradicts: The Physiological Effects of Weight-Cycling: A Review of Current Evidence. (Current obesity reports 2024) · cited 29x in the literature
"Twelve out of fourteen studies reported no adverse changes in RMR either. The overwhelming majority of evidence suggests that weight-cycling (yo-yo effect) is not associated with any adverse effects in body weight, body composition, and metabolic rate." (abstract, results, passage verified)
pubmedfull study (doi)