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Thermic Effect of Food

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 called diet-induced thermogenesis (DIT), specific dynamic action (SDA), or the thermic effect of food (TEF).

Our evidence-based analysis on thermic effect of food features 54 unique references to scientific papers.

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Summary of Thermic Effect of Food

Overview | How is the TEF assessed? | What affects the 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]

  • Fat provides 9 calories per gram, and its TEF is 0–5%.

  • 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
(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.[5]

What affects the TEF?

Supplements

Aside from a protein supplement, such as whey protein, no other supplements we’ve reviewed have had a notable effect on the TEF in either direction — increase or decrease. The table below displays an analysis of human studies and indicates how supplements may affect the TEF.

Meal frequency

A common claim is that more frequent meals create a higher total TEF over the course of a day, which can lead to greater fat loss. Consuming a single, giant meal will produce a greater thermogenic response than having a smaller meal, but if the TEF of all the small meals were added up, there looks to be no meaningful difference from a single, giant meal.

This has been demonstrated with one vs. two[6] meals, two vs. three[7] meals, and two vs. seven[8] meals. A study in humans — and an earlier study with dogs — showed a thermogenic benefit from higher meal frequency, but the bulk of evidence shows no TEF difference among meal frequencies.

Meal timing

There is a growing body of research indicating that the TEF may be lower for meals consumed in the evening or at night compared with a morning or afternoon meal.[9][10]

In one study (analyzed here in NERD), 20 healthy volunteers consumed a standardized meal at 8 a.m. or 8 p.m., and their metabolic response was measured. Eight hours before having the meal, participants consumed a slightly smaller standardized meal and were asked to spend the following six hours in bed. Values for the TEF were higher after the morning meal (328 kcal) compared with the evening meal (237 kcal).

This is consistent with previous research that reported a 31% relative decrease in the TEF after an evening meal, compared with one in the morning.[11]

Meal composition

As expected, meals higher in protein produce a higher TEF compared with those lower in protein.[12] But what about high-carb vs. high-fat meals? Most evidence, though scarce, points to high-carb meals producing a greater thermic effect when compared with high-fat meals.[13][14][15][12] 

But many factors can modify these results. Meals high in fiber may also increase the TEF.[16] Conversely, meals made mostly of highly refined or processed foods may produce a lower TEF.[17]

Body weight

The TEF response may actually be blunted in people with obesity or insulin resistance (which excess body fat can contribute to).[18][5] These small differences can add up over time. It is not clear just how much these conditions affect the TEF, though, as the research to date is not sufficient to confidently answer this question.[5]

Exercise

One study has suggested that physical activity, regardless of age or body composition, can increase the TEF.[19] The study compared active and sedentary men in a younger and older population. The TEF was higher in the active, younger group (323.42 vs 222.17 kcal) and the active, older group (292.04 vs 215.47 kcal) compared with their respective sedentary age counterparts.

Age

Three studies have shown that the TEF may decrease as you age. The largest, which had 123 participants, found that the TEF was about 1% lower in older subjects (60–88 years old) compared with younger ones (18–35).[20] Two smaller studies have also produced similar results.[21][22]

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Human Effect Matrix

Unlocked for Examine members

The Human Effect Matrix looks at human studies to tell you what supplements affect Thermic Effect of Food.

Full details on all Thermic Effect of Food supplements are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Supplement Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-c - - See study
No significant influence on the thermic effect of food
grade-d Minor - See study
Ginger has been found to increase the thermic effect of coingested food products
grade-d - - See study
Insufficient evidence to support alterations in the thermic effect of food compared to other oils

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Frequently Asked Questions and Articles on Thermic Effect of Food

Do you need to eat six times a day to keep your metabolism high?
Eating food six times a day, or very high meal frequency, does not seem to increase the overall metabolic rate more than simply eating three times a day. If such a meal frequency can help you feel better on a diet then it can be useful but it alone won't cause weight loss or prevent weight gain.

Things to Note

Also Known As

Diet-induced thermogenesis (DIT), Specific dynamic action (SDA), Thermic effect of food (TEF)

Click here to see all 54 references.