The thermal effect of food is the energy the body spends digesting, absorbing, and metabolising what we eat — also known as diet-induced thermogenesis. Every meal costs energy to process: roughly 20 to 30 percent of protein’s calories, 5 to 10 percent of carbohydrate’s, and under 5 percent of fat’s are burned in handling them. It is one of the three components of daily energy expenditure, alongside basal metabolic rate and physical activity, accounting for about a tenth of total calorie burn. The effect explains part of why high-protein diets aid weight control. It is a modest but real factor — not large enough to offset overeating, but one of the reasons whole, minimally processed foods cost more energy to digest.