Trascrizione (en)

When a skinny person eats a large amount of food without gaining weight, the reason lies in how their body uses energy. One major factor is NEAT. The calories burned through fidgeting, standing, pacing, and constant small movements. Naturally, lean people may burn far more energy this way without noticing. Muscle mass also matters because muscle uses more calories than fat even at rest. Genetics can slightly raise basal metabolic rate, while hormones such as ghrelin and leptin influence hunger and fullness. Some bodies also increase energy expenditure after eating through adaptive thermogenesis. Active brown fat can burn calories to produce heat, and gut bacteria may affect how efficiently energy is extracted from food. Calories still matter, but different bodies burn, store, and regulate energy differently. That is why the same meal can produce different results from one person to another.