Digestion has a price
Chewing, digesting, absorbing and storing food all cost energy. That cost — the Thermic Effect of Food, or TEF — accounts for roughly 10% of total daily expenditure for a typical mixed diet.
Eat 2,000 kcal and around 200 of them are spent processing the meal itself. It's the reason 'calories out' isn't fully independent of what you eat.
Not all macros cost the same
Protein: 20–30% of its calories are burned in processing — by far the most expensive macro, because amino acids require energy-intensive handling.
Carbohydrates: 5–10%, with complex carbs at the higher end.
Fat: just 0–3% — dietary fat is nearly free to store as body fat.
The practical consequence: 100 kcal of chicken breast nets your body roughly 75 kcal, while 100 kcal of butter nets about 98. Identical on the label, different in effect.
Using TEF to your advantage
A higher-protein diet measurably raises TEF — swapping 100 g of daily carbs for protein adds roughly 50–75 kcal of expenditure, on top of protein's superior satiety and muscle-sparing effects during a deficit.
Meal frequency, by contrast, is a myth lever: six small meals and two large ones with identical composition produce the same total TEF. 'Stoking the metabolic fire' with constant eating has been repeatedly debunked.
Put it into practice: run your own numbers with the related calculator — free, instant, and nothing leaves your browser.
Frequently asked questions
Do negative-calorie foods exist?
No food costs more to digest than it provides — celery comes closest and still nets positive. Very-low-calorie, high-fibre foods are useful for satiety, not negative math.
Does eating more often boost metabolism?
No — controlled studies show TEF is proportional to total intake and composition, not meal count. Choose a frequency you can stick to.
How much can a high-protein diet raise my daily burn?
Realistically 50–100 kcal/day versus a low-protein equivalent — modest alone, but it compounds with protein's satiety and muscle-retention benefits.
More guides
- What Is TDEE?
- What Is BMR?
- Mifflin-St Jeor Calculator
- Harris-Benedict Calculator
- Katch-McArdle Calculator
- BMR vs TDEE: What's the Difference?
- What Are MET Values?
- What Is NEAT?
- Activity Multipliers Explained
- What Is a Calorie?
- Metabolic Adaptation Explained
- The Calorie Deficit, Explained
- 500-Calorie Deficit
- 1,000-Calorie Deficit
- 300-Calorie Deficit
- How Many Calories to Lose 1 Pound a Week
- How Many Calories to Lose 2 Pounds a Week
- Reverse Dieting
- Maintenance Phase
- Calorie Cycling
- How Accurate Are TDEE Calculators?
- Not Losing Weight in a Calorie Deficit? 7 Real Reasons
- Is 1,200 Calories a Day Safe?
- Should You Eat Back Exercise Calories?
- How Long Does Metabolic Adaptation Last?
- Do You Burn Fewer Calories as You Lose Weight?
- Why Your Maintenance Calories Keep Changing
- Calorie Cycling vs Flat Deficit
- How to Avoid Muscle Loss on GLP-1 Medications
Sources
- Westerterp KR. Diet induced thermogenesis. Nutr Metab (Lond). 2004;1(1):5.
- Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss. J Am Coll Nutr. 2004.