Your body burns more calories digesting protein than carbs or fat.

We analyzed two assertions about diet-induced thermogenesis and protein, and what we’ve found so far leans toward the idea that protein raises energy expenditure more than carbs or fats because of the metabolic effort needed to process it [1]. Both assertions point to the same mechanism — the higher cost of absorbing, transporting, and turning amino acids into usable forms — and each was supported by 61 studies while 42 studies offered contrary findings [2]. This doesn’t mean protein always burns more calories in every person or every situation, but across the studies we reviewed, the pattern appears consistent enough to suggest a meaningful difference. The body uses more energy to handle protein than it does for the other macronutrients, even when the total calories are the same. That’s because protein requires more steps — like breaking down complex molecules, moving amino acids into cells, and rebuilding them into new proteins — and each step uses fuel. Still, the fact that nearly half of the studies didn’t find the same effect means the difference isn’t universal. Factors like age, activity level, overall diet, and how the protein is prepared may change how much extra energy is burned. We don’t have enough detail from the studies to say exactly why some results differ. What this means for everyday life: if you’re eating more protein, your body may naturally burn a bit more calories during digestion — not a huge amount, but it adds up over time. It’s one small reason why high-protein diets sometimes feel different in terms of fullness or energy use, even when calories are matched. But don’t expect it to be a magic boost — it’s just one part of a bigger picture.