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The thermic effect of food explained
Digesting food isn't free — it costs your body calories, and that cost depends on what you're eating.
The Thermic Effect of Food (TEF), also called diet-induced thermogenesis, is the energy your body spends digesting, absorbing, and metabolizing what you eat. It's a real (if modest) component of total daily energy expenditure, and it varies significantly by macronutrient:
| Macronutrient | Approximate TEF |
|---|---|
| Protein | 20-30% of its calories |
| Carbohydrate | 5-10% of its calories |
| Fat | 0-3% of its calories |
In practice, this means a higher-protein diet burns modestly more calories through digestion alone than an equal-calorie lower-protein diet — one small piece of why higher protein intakes are often recommended during a fat-loss phase, alongside protein's larger effects on satiety and muscle preservation.[1] TEF is a real effect, but it's a modest slice of total daily expenditure — not a substitute for an appropriate overall calorie target.
Keep reading: BMR vs. TDEE · Macros for fat loss · How much protein per day