Metabolism, the set of chemical reactions that take place in the body’s cells to convert food into energy, is a convenient and habitual victim of justifying weight gain, arguing that the body loses the ability to burn calories. An article published on Thursday in the magazine Sciences He refutes this belief and reveals that this ability increases in the first year of life – when the body needs to complete the maturation of its systems – and decreases until the age of twenty, remains constant until the age of sixty, and decreases with age.
The study, whose lead author was Hermann Pontzer of Duke University (USA), collected information from 6,500 people between the ages of 8 days and 95 years. In addition to identifying the four basic periods of metabolism, it also ends another gender myth. According to the research, “there are no real differences between the metabolic rates of men and women if the conditions are similar.”
The work reveals that “total daily energy expenditure accelerates rapidly in newborns and is up to twice the average value in adults.” However, after a year, it decreases until it reaches levels that remain stable between the ages of 20 and 60 years. From this age onwards, this characteristic decreases until it reaches its lowest levels in the later years of life. “These changes shed light on human development and aging, and should help shape nutrition and lifelong health strategies,” Ponzer says.
Rozalyn Anderson, MD, professor of medicine at the University of Wisconsin-Madison, where the expert studies aging, complements Pontzer’s work with an article that accompanies the research and highlights that it leads to a review of existing ideas. In this sense, he says: “Metabolism is not just about energy, it is about how the body processes nutritious fuel and converts it into usable energy currency. Metabolism is also concerned with elements such as synthesis, modification and exchange of all aspects of cell function. It acts as a sensor and regulator. The energetic requirements of activity are imposed physical on highly integrated equipment.”
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Samuel Klein, MD, director of the Center for Human Nutrition at the University of Washington School of Medicine, who was not part of the study, summarized: New York times How work separates weight gain from metabolism with a simple and understandable analysis: “When it comes to weight gain, the problem is always the same: people eat more calories than they burn.”
In the case of children, Pontzer says, for those who are more justified in higher energy expenditures, the study reveals something unknown: “Of course they are growing, but even when this is controlled, their energy expenditure rises more than would be expected for its size. And body composition. Something is going on inside the baby’s cells to make them more active and we still don’t know what those processes are.”
According to Duke University, where the study’s lead author is working, “Children’s metabolism may explain in part why children who do not eat enough during this period of development are less likely to survive and grow into healthy adults.”
This accelerated metabolism of children decreases at a rate of 3% each year until they reach the age of 20. Not even adolescence changed this slight progress. Pontzer admits: “We thought puberty would be different. And it isn’t.”
The research shows that energy expenditure remains stable until the age of 60, even in pregnancy conditions, when it is possible to believe that pregnancy requires greater expenditure. The study, however, ignores this hypothesis.
Metabolism does not begin to lose capacity until the age of 60 years. Since then, 0.7% of energy is lost each year, so a ninety-year-old needs 26% fewer calories than he did forty years ago.
Ponzer concludes, “There are many physiological changes that occur as you age. Let’s think about puberty, menopause, and other stages of life. Surprisingly enough, the calendar of metabolic stages in our lives does not seem to coincide with these events.”
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