Which component of energy expenditure represents energy used to digest, absorb, and metabolize nutrients?

• A. Basal metabolic rate
• B. Thermic effect of food
• C. Physical activity
• D. Adaptive thermogenesis

Answer: (B)

Digestion, absorption, and the metabolic processing of nutrients require energy, and this cost is known as the thermic effect of food. It represents the energy spent by the body to break down foods into usable components, transport them to tissues, and convert nutrients into body tissues and energy. Because different nutrients demand different amounts of work, the thermic effect varies with what you eat: protein has the highest cost, carbohydrates are moderate, and fats are the lowest. On average, it accounts for about one-tenth of total energy intake, though a high-protein meal or meals spread across the day can raise that proportion.

This helps distinguish TEF from the other components: basal metabolic rate is the energy needed to keep essential body functions alive at rest, independent of food intake; physical activity energy is the energy expended during movement and exercise; adaptive thermogenesis refers to adjustments in energy expenditure in response to environmental factors or overfeeding. The thermic effect of food is specifically tied to processing the food you consume, making it the best fit for energy spent on digestion, absorption, and metabolism.