Thermic Effect of Food (TEF) Calculator

Understanding the thermic effect of food (TEF) calculator — concept and principle

The thermic effect of food (TEF), also called diet-induced thermogenesis, is the energy your body spends digesting, absorbing and storing what you eat. This calculator estimates TEF from your daily protein, carbohydrate and fat, and shows how much of your intake it represents. It is useful for understanding why high-protein diets are slightly "cheaper" in net calories.

Protein has by far the largest digestion cost — here 150 of the 238 kcal.

How it is calculated

Energy from each macronutrient: protein × 4 kcal/g, carbohydrate × 4 kcal/g, fat × 9 kcal/g.
TEF = protein kcal × 0.25 + carbohydrate kcal × 0.075 + fat kcal × 0.02.
Total calories eaten = p × 4 + c × 4 + f × 9.
TEF % of intake = TEF ÷ total × 100.

The factors 25%, 7.5% and 2% sit within the commonly quoted ranges of 20–30% for protein, 5–10% for carbohydrate and 0–3% for fat.

The principle

Each nutrient is handled differently. Amino acids cannot be stored as such: building them into proteins costs ATP (peptide bonds are expensive), and converting surplus amino acids into glucose or urea costs more. Carbohydrate needs energy to be stored as glycogen, and more if it is turned into fat. Dietary fat is the cheapest: it is absorbed and placed into fat tissue with very little loss. Adding the costs gives the total heat produced after meals, which on a mixed diet is usually about 10% of energy intake.

Worked example

Inputs: protein 150 g, carbohydrate 250 g, fat 70 g.
Calories: 150 × 4 = 600, 250 × 4 = 1,000, 70 × 9 = 630; total = 2,230 kcal.
TEF = 600 × 0.25 + 1,000 × 0.075 + 630 × 0.02 = 150 + 75 + 12.6 = 237.6, shown as 238 kcal.
TEF % = 237.6 ÷ 2,230 × 100 = 10.65%.

Each point is the calculator re-run with only “Protein (g)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Protein (g)	TEF (kcal)
37.5	125
75	163
112	200
150	238
188	275
225	313
300	388

How to read the result

Around 10% is typical for a balanced diet. A protein-heavy diet may reach 12–15%; a high-fat, low-protein diet may fall to 6–8%. The difference between diets is usually only 50–150 kcal a day, real but modest. Highly processed foods may produce a slightly lower TEF than whole foods with the same macros, which this formula cannot capture.

Common mistakes

Subtracting TEF from a TDEE figure; standard TDEE equations already include about 10% TEF.
Expecting "negative-calorie" foods: no food costs more to digest than it supplies.
Forgetting that alcohol (7 kcal/g) and fibre are not included here.

Keep in mind: TEF varies with meal size, food processing, age and insulin sensitivity. These are approximate textbook ranges, not a measurement and not medical advice.

Frequently asked questions

Why is protein's thermic effect so high?

Making and breaking peptide bonds and disposing of nitrogen as urea need a lot of ATP, so about a quarter of protein energy is lost as heat.

Does eating more meals raise TEF?

Not meaningfully. TEF follows total intake; six small meals and three large ones with the same food give similar totals.

Can I use TEF to lose weight?

Swapping some carbohydrate or fat for protein slightly raises TEF and improves fullness, but total intake matters much more.

Sources: Westerterp KR. Diet induced thermogenesis. Nutrition & Metabolism 2004.

Checked 8 Nov 2026. Published formulas cited on the page. For information only — not medical advice.

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