It may seem contradictory, but eating uses energy. The reason is very simple: digestion itself and all the processes of absorption and metabolism, essential for our body to obtain the nutrients necessary for its vital functions, require caloric expenditure (also called energy consumption or, in street language, burning calories).
But our body also consumes energy to carry out daily activities. This is known as CLEAN (acronym of activity thermogenesis without exercise) and encompasses any activity not associated with physical exercise that burns energy, that is, all our actions, except eating, sleeping and exercising. They are all those daily activities that are not sports and which include climbing the subway stairs, walking, hanging clothes, vacuuming or going shopping. These activities, individually, have little energy expenditure. But their cumulative effect ends up being more important than we think.
In fact, staying active and carrying out a wide range of diverse activities is a very good indicator of quality of life and maintenance of our lean body mass. Especially when we get older.
Types of thermogenesis
All this expense not associated with sports exercise can be summarized in a single word: thermogenesis. Within this concept, in turn, different types of thermogenesis must be differentiated.
- Heat generation (metabolism)
- Obligatory dietary thermogenesis.
- Adaptive thermogenesis
Thermogenesis as an expenditure of metabolism.
Manuel López Cabanillas, dietitian-nutritionist and member of the Spanish Academy of Nutrition and Dietetics, defines the first type of thermogenesis (heat genesis) as “the obtaining of heat resulting from basic metabolic functions. Thanks to it, body temperature can be maintained stable without the participation of additional mechanisms.” This includes all the functions of basal metabolism or energy expenditure at rest due to the functioning of the different physiological systems necessary for survival.
Thermogenesis of macronutrients or mandatory thermogenesis of the diet.
«The macronutrient thermogenesis It is the increase in energy expenditure associated with the consumption of a certain type of food. It is the energy needed to digest, absorb and metabolize nutrientsin addition to its subsequent storage,” explains the expert.
In other words, eating, or, rather, digesting and metabolizing nutrients, is one of the ways the body uses energy without us being aware of it.
The different pathways of dietary obligatory thermogenesis.
We have already seen that our body has to make an energetic effort to digest food and that this effort entails a certain consumption of calories. Now, not all foods induce the expenditure of the same amount of calories, because Not all foods require the same energy to be digested..
To metabolize and use our body’s proteins, a caloric expenditure of approximately 20% to 30% of its caloric value is required, which is 4 kilocalories per gram.
Carbohydrates require a caloric expenditure between 5% and 10% of their energy, which is 4 kilocalories for each gram. That is, a smaller amount of energy is needed (fewer calories are burned) to use carbohydrates compared to proteins.
Regarding fats, their energy expenditure is between 1% and 3%. It is the macronutrient with the lowest thermogenic effect. Each gram of fat provides 9 kilocalories.
For every 100 kilocalories ingested, our body will spend about 20-30 kilocalories for proteins, 5-10 kilocalories for carbohydrates and 1-5 kilocalories for fats in thermogenesis.
‘Thermogenic’ foods: your diet also generates heat
Another concept is what is called ‘thermogenic foods‘. This name refers to those foods that have compounds, such as capsaicin from pepper, or gingerols from ginger, that stimulate the central nervous system, increase energy expenditure and generate more calories during digestion and metabolism.
Thermogenic foods include:
- Proteins: fish, meat, eggs, seafood, legumes
- Cocoa
- guarana
- Café
- Green Tea
- hot paprika
- black pepper
- Ginger
Before venturing to base our diet on very thermogenic foods as an excuse to lose weight, the expert warns that the intake of thermogenic foods should be moderate, especially in the case of those that contain stimulating substances. Coffee or green tea can cause effects such as insomnia or increased heart rate, due to their caffeine content.
Adaptive or facultative thermogenesis: Can cold help burn fat?
Indeed, The cold can help you burn more calories. The reason is the difference between the two types of fat in our body: brown fat (whose function is to generate heat) and white fat (it is stored to generate energy). “Brown fat stimulates the use of free fatty acids. It is activated in excessively cold environments to generate heat and maintain body temperature,” says López Cabanillas. Hence, energy expenditure increases.
Now, we must keep in mind that not all people respond in the same way to stimuli such as cold and other agents that stimulate thermogenesis.
Just as exposure to cold, exposure to a Excessive caloric intake can stimulate heat production. This capacity, however, varies greatly depending on each person.
María Jesús Obregón, member of the CSIC Biomedical Research Institute, defines adaptive thermogenesis as “the heat produced in response to exposure to cold or a high-calorie diet. It is regulated by the sympathetic nervous system and means that, in different people, the same food will generate the same energy, but in one it is transformed into the form of heat and in others it passes into body deposits.»
Regarding whether adaptive thermogenesis influences body weight, Manuel López Cabanillas states that “it will depend on the caloric balance, the size of the portions, and the amount of muscle mass and brown fat that exists, which is greater in children and adolescents. than in adults.”
Physical activity: the other heat that burns many more calories
A healthy way of increasing our energy expenditure at rest and, in the process, gaining health, is to stay in shape by doing sports on a regular basis.. “Physical activity helps to generate more muscle mass and this helps to modulate thermogenesis. Having more muscle can help burn between 100 and 300 more kilocalories per day,” says López Cabanillas.
The ALDI Council
Nutrition labels indicate calories per 100 grams of product, but the serving size is not always exactly that amount. Keep this in mind when estimating the calories of each dish.
Manuel Lopez Cabanillas. Honorary Member of the Spanish Academy of Nutrition and Dietetics. He has a degree in Nutrition from the Autonomous University of Nuevo León (Mexico), a master’s degree in Food Biotechnology from the Polytechnic University of Catalonia, a master’s degree in Food Science and a PhD in Food Science from the Autonomous University of Barcelona. He has 30 years of experience in teaching and research at the UANL. He is currently director of the Faculty of Public Health and Nutrition at the UANL and president of the National Council for the Quality of Educational Programs in Nutrition, AC (CONCAPREN). He teaches the chair of Innovation in Food Production in the Bachelor’s Degree in Nutrition; Intervention Strategies in Nutrition, Functional Foods and Health, Food Analysis Laboratory, Experimental Diet Design Laboratory, Thesis I and Thesis II in the Master of Science in Nutrition. He has contributed to different national and international associations such as the Mexican College of Nutritionists AC, the Mexican Association of Members of Faculties and Schools of Nutrition, AC (AMMFEN), in addition to belonging to the Mexican Society of Nutrition and Endocrinology Northeast Chapter.
