The Thermic Effect of Food: What Is It and How Does it Work?

When calculating energy requirements, the thermic effect of foods must be taken into account. This depends on the nutrients in the food.
The Thermic Effect of Food: What Is It and How Does it Work?
Saúl Sánchez Arias

Written and verified by the nutritionist Saúl Sánchez Arias.

Last update: 27 September, 2022

The thermic effect of food is the amount of energy needed to process the food and to get the nutrients out of it. It’s the result of digestion, absorption, and metabolism.

It is also known as “postprandial thermogenesis” and can determine daily energy expenditure. For this reason, it’s important to take it into account when establishing a person’s calorie needs.

Before we begin, it should be noted that calculations of energy requirements are always approximate. There are various formulas for making estimates, but it isn’t really possible to know the exact value.

In any case, it isn’t excessively relevant. Making subsequent dietary adjustments based on the results obtained will be sufficient to improve body composition.

Thermic effect of food

Normally, the thermic effect of food is determined by the amount and proportion of nutrients in the food. Therefore, not all foodstuffs have a similar value, but different calculations should be made to determine the result of each of the products that make up the diet.

A healthy lunch.
The thermic effect indicates the amount of energy needed to process the nutrients during digestion

Generally speaking, 25% of the caloric value of a protein is necessary for the digestion and metabolism of the protein. As for carbohydrates, only 10% of the total energy will be used for these processes. When it comes to fats, the thermic effect is even smaller. Only 2% of the energy they provide is enough to ensure optimal digestion with their subsequent metabolism.

However, there are other values that can affect the thermic effect of food. One of them is physical exercise. For example, a workout after a high protein intake could increase the amount needed for digestion by 5 to 10%. Fiber is another of the components that will have an impact, also modulating the sensation of satiety. This is evidenced by a study published in Nutrition Reviews.

Toxic habits could even reduce this value. An example would be smoking. Also, stimulating substances such as coffee could provoke variations in the energy expenditure derived from the metabolism of nutrients. However, the amount of the change isn’t known with certainty.

Is the thermic effect significant in weight loss?

Although food requires energy to be metabolized, this expenditure won’t be very influential on the state of body composition. Initially, it was believed that a high-protein diet could improve the energy deficit, due to the higher caloric requirements for metabolism. However, the truth is that such a diet leads to gains because it generates greater satiety and contributes to muscle retention.

Ultimately, in order to experience body fat loss, it will be key to consolidate an energy deficit. This can be achieved through dietary restriction, although it’s much smarter to do so through physical exercise. For example, HIIT has shown great benefits in increasing daily expenditure and subsequent metabolic activity.

A woman doing exercises.
Physical exercise is essential to promote weight loss.

One of the keys will undoubtedly be the consolidation of new muscle mass. Lean tissue is metabolically very active, so it will help to increase daily caloric needs. If they aren’t compensated by the diet, a deficit will be established which will be paid off by mobilization and subsequent oxidation of fatty acids. However, for this to work, certain dietary adjustments will have to be made.

Ensuring sufficient protein intake will make a difference. These nutrients retain muscle mass and promote its development. At least 0.8 grams per kilogram of body weight per day is required for sedentary people.

However, when it comes to athletes, these requirements can easily double or triple. This is evidenced by research published in the Journal of the International Society of Sports Nutrition.

You may also be interested in: What’s Metabolism? Is Yours Fast or Slow?

Thermic effect of food, an element to take into account

As you have seen, the processing of food and nutrients inside the body costs energy. This must be taken into account when calculating a person’s caloric needs.

This will give a more accurate result that can lead to benefits in terms of body composition over time. However, it isn’t the only thing that matters when it comes to achieving this goal.

Finally, keep in mind that physical activity will make a difference in metabolism. It will increase your total daily energy expenditure, which will allow you to establish a deficit that will subsequently stimulate fat loss.

However, to maximize your gains, it is important to adjust your nutritional regimen and plan your workouts correctly. Generally speaking, it is a good idea to give greater priority to strength and resistance training.

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  • Wewege M, van den Berg R, Ward RE, Keech A. The effects of high-intensity interval training vs. moderate-intensity continuous training on body composition in overweight and obese adults: a systematic review and meta-analysis. Obes Rev. 2017;18(6):635-646. doi:10.1111/obr.12532
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