What is Thermic Effect of Food?
Short for TEF
Also: TEF · diet-induced thermogenesis
The 10% or so of calories your body burns just digesting what you ate.
The thermic effect of food (TEF), sometimes called diet-induced thermogenesis, is the energy your body spends digesting, absorbing, and processing what you eat. For a mixed diet it accounts for roughly 10 percent of total calorie burn. Protein has the highest TEF (20 to 30 percent of its calories), carbohydrates sit around 5 to 10 percent, and dietary fat is the lowest at 0 to 3 percent.
Quick definition
TEF is the smallest slice of your TDEE, but it's the one most easily moved by food choice. Eat a 600-calorie steak, you net only about 450 calories of usable energy after digestion. Eat 600 calories of olive oil, you net almost the full 600.
How it actually works
Digestion isn't free. Your body uses ATP to break down food, transport nutrients across the gut wall, package them into bloodstream-ready molecules, and either store them or send them where they're needed. The higher the protein content of a meal, the more processing required — and the more heat thrown off in the process. That's why high-protein meals literally feel warmer 30 to 60 minutes after eating.
For a typical 2,200-calorie diet, TEF accounts for about 220 calories a day. Increase the protein share from 15 percent to 30 percent of total intake — without changing total calories — and TEF climbs roughly 50 to 80 additional calories per day. Stacked over a year, that's 5 to 8 pounds of fat.
This is one of the reasons high-protein diets out-perform same-calorie low-protein diets in basically every randomized trial. The International Society of Sports Nutrition position stand (Jäger et al., 2017) recommends 0.7 to 1.0 grams of protein per pound of bodyweight for active adults trying to maintain lean body mass during a deficit.
Why it matters for weight loss
TEF is small but real, and protein is the cheapest way to nudge it up. The honest reason most fitness writers push protein isn't TEF in isolation — it's the stack: more muscle protein synthesis, better satiety (you eat less), and modest TEF gains. The combination is the whole game.
Our 7-day meal plan front-loads protein for exactly this reason — 30 to 40 grams per meal across three meals beats spiking it all at dinner.
Common misconceptions
The biggest TEF myth is "negative calorie foods" — celery, cucumber, lettuce. The claim is digesting them burns more calories than they contain. There's no published evidence this is true at meaningful scale. The math on celery (6 calories per stalk) at a 10 percent TEF is half a calorie. Not a fat-loss strategy.
The second myth: spicy food dramatically raises TEF via capsaicin. Multiple studies show a small, real effect (5 to 30 extra calories per meal). Real, but rounds to nothing. The marketing version that "hot sauce melts fat" is recycled supplement-funnel copy.
Related terms
- TDEE · Total Daily Energy Expenditure Everything you burn in 24 hours — BMR plus movement, digestion, and fidgeting.
- BMR · Basal Metabolic Rate The calories your body burns at complete rest just to keep you alive.
- NEAT · Non-Exercise Activity Thermogenesis Calories burned by everything that isn't exercise — fidgeting, walking, standing, chores.
- Muscle Protein Synthesis · MPS The process of building new muscle tissue. Driven by protein intake and resistance training.
- Calorie Deficit Eating fewer calories than you burn — the only mechanism that produces fat loss.
Read next on Real Easy Diet
Sources
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Protein and weight loss — Harvard Health Harvard Health
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