Thermic effect of food (TEF)

Last Updated: August 17 2022

Some of the calories in the food you eat are used to digest, absorb, metabolize, and store the remaining food, and some are burned off as heat. This process is known under various names, notably diet-induced thermogenesis (DIT), specific dynamic action (SDA), and the thermic effect of food (TEF).

Overview

Some of the calories in the food you eat are used to digest, absorb, metabolize, and store the remaining food, and some are burned off as heat. This process is known under various names, notably diet-induced thermogenesis (DIT), specific dynamic action (SDA), and the thermic effect of food (TEF).[1][2]

The TEF represents about 10% of the caloric intake of healthy adults who eat a standard mixed-macronutrient diet,[3] but your actual number will depend on several factors, including your age and the meal timing, and macronutrient composition — carbs, fat, and protein — of your meal. The energy required to digest each macronutrient (its TEF) can be expressed as a percentage of the energy provided by the macronutrient:[4][5]

  • Fat provides 9 calories per gram, and its TEF is 0–3%.
  • Carbohydrate provides 4 calories per gram, and its TEF is 5–10%.
  • Protein provides 4 calories per gram, and its TEF is 20–30%.

Resting metabolic rate (RMR) refers to the amount of energy used while the body is at rest. To put it another way, it’s how many calories your body would use if you were lying down all day. The TEF is related to this measure, as it refers to the increase in RMR after the consumption of food and accounts for about 10% of daily energy expenditure, as we noted above.

How is the TEF assessed?

There are several methods used for measuring the TEF, as seen in the table below. All come with varying degrees of complexity, cost, accuracy, and reliability. These measurements must be done in a laboratory or clinical setting with specialized equipment and trained technicians.

Methods used to measure the thermic effect of food (TEF)

METHODCOMPLEXITYCOSTMEASUREMENT TIME[BR](in hours)

Confinement system

High

Moderate/high

1–48

Metabolic chamber

High

Moderate/high

2–48

Respiratory chamber

High

Moderate/high

1–100

Ventilated hood/canopy

Moderate

Low/moderate

0.2–6

Isotope dilution

Low

High

48–240

Adapted from Calcagno et al. J Am Coll Nutr. 2019.[6]

Examine Database: Thermic effect of food (TEF)
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