[1][2] Set point theory explains why it is difficult for dieters to maintain weight loss over time, as calorie restriction may become less effective or more difficult to maintain as regulatory mechanisms in the body actively push the body back towards the set point weight.
Passive compensation describes processes where a decrease in body fat leads to less energy being expended, because one carries around less weight in daily activities.
In humans, when calories are restricted because of war, famine, or diet, lost weight is typically regained quickly, including for obese patients.
[9] As there has not been one unique mechanism identified to be behind weight regulation, it is likely that there are multiple factors reaching a shared equilibrium that result in a stable bodyweight.
Changing leptin levels – either associated with weight gain or loss, or induced via central or peripheral administration in animal models – directly alter feeding behaviour and energy expenditure.
[4] In the dual intervention model, the lower and upper limits of the range are independently set, with the lower end of the range set by evolutionary pressure due to the risk of starvation if too much weight is lost and the upper bound set by pressure due to increased risk of predation if too much weight is gained.