TEF (Thermic Effect of Food)

What is TEF? The definition in 20 seconds

TEF is the energy spent after a meal on digesting, absorbing and processing nutrients. It is one of the four components of your TDEE, alongside BMR, NEAT and EAT. On a mixed diet it makes up 5 to 15 percent of your daily expenditure.

• The order: The effect is highest for alcohol and protein, followed by carbohydrates, and lowest for fat.
• Small but steady: TEF runs along with every meal. You should know it, but not chase it.
• For hardgainers this means: Protein costs a bit more energy and fills you up more. That is exactly what counts when your appetite is already tight.

The anchors in the system: your metabolism, the Metabolism System and your maintenance calories.

What you control and what you don't

TEF depends mainly on two things: how much you eat and how high your protein share is. You control both. Not the effect itself.

• Total intake: More food means more TEF. It grows with your surplus but stays a small part of it.
• Protein share: You need enough protein to build muscle. If you fill up fast, add extra calories through carbs and fat rather than even more protein.
• Distribution: 3 to 4 meals with enough protein each cover the leucine threshold. Pick your number of meals based on your day and your appetite, not on TEF.
• What you don't control: No food “fires up” your metabolism enough to turn TEF into a lever. It stays a side calculation.

Practice: the 14-day check

• Day 0, set your base: Set your calorie target at maintenance plus 150 to 250 kcal per day, our deliberately cautious starting value. Fix a protein target per meal and plan 3 to 4 meals.
• Document daily: Morning bodyweight, rough calories and protein, fullness after meals on a scale of 1 to 10 and steps. Build weekly averages. How much your steps burn is shown by the NEAT Calculator.
• Day 14, check the trend: Is your rate of gain flat while you feel full all the time? Then hold your protein target and add the missing calories through carbs and fat instead of just making portions bigger.

TEF is the side calculation. Whether you gain is shown by the scale.

Common misconceptions

• “The more protein, the better, TEF burns off the rest.” Protein raises TEF, but it stays a small part of your expenditure. Too much protein on a tight appetite mostly costs you room in your stomach.
• “I eat loads of protein but can't gain weight.” Protein is very filling and costs a bit more energy. On a tight surplus that can be enough to shrink it. Recheck your maintenance and shift calories towards carbs and fat.
• “Certain foods boost your metabolism.” No food turns TEF into a lever. What matters is the amount and makeup of your diet across the whole day.
• “More protein upsets my stomach, so I can't handle it.” Increase it step by step and watch your food hygiene. Often the portions are simply too big at once.

Common questions