Energy balance

Following behavioral weight loss, the body enters a physiological state characterized by adaptive thermogenesis (declines in energy expenditure beyond those attributable to changes in body composition) and increased energy intake, which drive weight regain.

After losing weight, your body biologically fights to regain it by lowering your energy expenditure and increasing hunger. This is a normal physiological response, not a personal failure. To maintain weight loss, you must account for these biological changes, likely requiring ongoing behavioral support and potentially adjusted energy intake/expenditure strategies, rather than relying on the same intensity of effort used during the weight loss phase.