Undoubtedly most of us remember with longing and longing, that time in our life when we could eat whatever we wanted and not gain weight. And in a way we have ended up relating weight gain with age, which is a completely wrong concept and in fact is suggested by a new study in which it was found that metabolism, actually peaks much earlier in life and its inevitable decline begins later than we imagine. It is a fact that there are many other factors.
Therefore it suggests that weight gain as we get older cannot be due to a slowdown in metabolism. The findings of this interesting research work were published in the journal Science and spearheaded by the Duke University. According to co-author Herman Pontzer, associate professor of evolutionary anthropology at Duke University: “There are many physiological changes that come with growth and aging. Let’s think about puberty, menopause, other phases of life. The strange thing is that the moment of our ‘metabolic stages of life’ it does not seem to coincide with those typical milestones ”.
What did the study consist of? Pontzer and an international team of scientists analyzed the average calories burned by more than 6,600 people with age ranges from 7 days old to 95 years old while going about their daily lives in 29 countries around the world.
As a background, it is known that most large-scale studies measured how much energy the body uses to perform basic vital functions such as breathe, digest, pump blood; in other words, the calories we need simply to stay alive. These aspects are equivalent to only 50% to 70% of the calories we burn each day. In other words, the energy we spend on everything else was not taken into account: washing the dishes, walking the dog, sweating in the gym, even thinking or fidgeting.
So to arrive at a number for total daily energy expenditure, the researchers relied on the method of “Double labeled water“. It is a urine test that involves a person drinking water in which the hydrogen and oxygen in the water molecules have been replaced by naturally occurring “heavy” forms, and then measuring how quickly they are removed. This is not a new method, scientists have since used this technique to measure energy expenditure in humans since the 1980s, which is considered the gold standard for measuring daily energy expenditure during normal daily life, outside the laboratory. However, the studies have been limited in size and scope due to cost. Therefore, several laboratories decided to share their data and collect their measurements in a single database, to see if they could unravel truths that have not been revealed in previous work.
As expected, relevant results were obtained, thanks to the grouping and analysis of energy costs throughout the entire useful life of the participants. One of the biggest surprises was:Some people think of adolescence and 20s as the age when their potential for burning calories peaks. But the researchers found that, pound for pound, the babies had the highest metabolic rates of all.
Energy needs skyrocket during the first 12 months of life, so by your first birthday, a one-year-old child burns calories 50% faster for his body size than an adult.And that’s not just because, in their first year, babies are busy tripling their birth weight. Babies are clearly growing, according to Pontzer, but even once you control that, their energy expenditures skyrocket more than you would expect for their body size and composition. What is a fact is that something is happening inside the cells of a baby to make them more active, although according to scientists they are not yet clear what those processes are.
After the initial increase in infancy, the data showed that metabolism slows by about 3% each year until we reach our 20s, when it stabilizes in a new normal in the body. Despite the fact that adolescence is a time of growth spurt, the researchers did not see any increase in daily caloric needs in adolescence after taking body size into account. According to Pontzer, this was a very important finding as they thought puberty would be different and it is not.
Middle age was another surprise. Especially considering the popular belief about how much it costs to lose weight after 30 years. The study showed that several factors could explain the thickening of the waist that often arise during our best years of life and work, however the findings suggest that a changing metabolism is not one of them. In fact, the researchers found that energy expenditures during these intervening decades (our 20s, 30s, 40s and 50s) they were the most stable. Even during pregnancy, a woman’s caloric needs were neither higher nor lower than expected.
So the data suggest that metabolism doesn’t really start to slow down again until after age 60. The slowdown is gradual, only 0.7% per year. Thus, a 90-year-old person will need 26% fewer calories per day than a middle-aged person. One of the possible reasons that researchers point out is the loss of muscle mass as we age: muscle burns more calories than fat. However, it is not the complete picture, it is important to control muscle mass because it reflects that the cells are slowing down. It is worth mentioning that these patterns were maintained even when the different levels of activity were taken into account.
The reality is that metabolism has long been a complex issue, as what drives changes in energy expenditure has been difficult to analyze because aging goes hand in hand with many other changes. But research supports the idea that it’s about more than age-related changes in lifestyle or body composition. Ultimately the results are wonderful and point to the fact that tissue metabolism, the work that cells do, is changing throughout life in ways that we had not fully appreciated before.
It may interest you