Metabolic Adaptation

When you cut calories sharply, your body fights back. This response — called adaptive thermogenesis — lowers your metabolic rate beyond what weight loss alone would predict. Your body becomes more efficient, burning fewer calories for the same activities.

Contestants on extreme weight-loss shows showed this dramatically. Years later, their resting metabolism was still suppressed by hundreds of calories a day compared with people of similar size who never dieted.

The antidote is patience. Gradual deficits of 300-500 calories minimize the slowdown, and resistance training builds active tissue that partly counteracts it.