Which macronutrient has the highest thermic effect of food (TEF)?

• A. Carbohydrate
• B. Fat
• C. Alcohol
• D. Protein

Answer: (D)

Thermic effect of food is the energy the body uses to digest, absorb, and metabolize nutrients. Protein stands out because processing amino acids involves more demanding steps—deamination, urea production, and the synthesis of new proteins—so it costs more energy to handle each unit of protein. That extra energy expenditure means protein has the highest TEF among the macronutrients. Carbohydrates require less energy to digest and store, and fats require even less due to their more straightforward digestion and storage. Alcohol isn’t a macronutrient in the same sense, and while it has its own energy cost, it’s not grouped with the macronutrients; among the listed options, protein has the highest TEF.