"Avoid yo-yo dieting to protect metabolic capacity Research cited in the episode shows that when people lose weight rapidly without resistance training or sufficient protein, up to half the weight lost can come from lean mass — and when weight is regained, "fat mass goes up much more rapidly" while lean mass returns very sluggishly. Over multiple cycles this leaves a person with progressively less muscle and more fat, lowering their metabolic rate and making future fat loss harder. The solution is a targeted calorie deficit of no more than roughly 500 calories per day, paired with resistance training and adequate protein, then a deliberate return to maintenance or a slight surplus. Source: Lane Norton, Forever Strong Experience, Nutrition and Body Composition Episode"