Nutrition glossary
What Is TEF?
**TEF (Thermic Effect of Food)** is the energy your body spends digesting and processing what you eat. It accounts for roughly 10% of your daily calorie intake, and protein has by far the highest thermic effect of the macros.
In short, eating costs energy — and what you eat changes how much that costs.
Short answer
TEF (Thermic Effect of Food) is the energy your body spends digesting and processing what you eat. It accounts for roughly 10% of your daily calorie intake, and protein has by far the highest thermic effect of the macros.
How it works
Digesting, absorbing, and storing food all take energy, so you never keep 100% of the calories you eat. TEF is that processing cost, and it differs sharply by macro:
- Protein — about 20–30% of its calories spent digesting it (the highest by far)
- Carbohydrates — roughly 5–10%
- Fat — only about 0–3%
Why it matters for your goals
TEF is one of the four parts of your TDEE, alongside your BMR, NEAT, and exercise. It's modest — around 10% of intake — so no single food meaningfully changes your total on its own.
But because protein carries the biggest thermic cost, a higher-protein diet quietly nudges your daily burn up while also keeping you fuller and protecting muscle. It's a small effect that lines up neatly with everything else protein already does well.
Frequently asked questions
How much does TEF affect my calorie burn?
TEF accounts for roughly 10% of the calories you eat each day. It's a real but modest slice of your total burn, smaller than your BMR and usually smaller than your daily NEAT.
Why does protein have the highest TEF?
Protein is metabolically expensive to break down and process — your body spends around 20–30% of its calories digesting it, versus about 5–10% for carbs and almost nothing for fat.
Are there foods that burn more calories than they contain?
No. The idea of 'negative-calorie' foods is a myth. TEF only reclaims a fraction of a food's energy; you always net positive calories from anything you eat.
Keep exploring
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