A study showed that humans burn calories much earlier than previously thought, and the rate of decline is much later.
Researchers analyzed the calories consumed in daily life by more than 6,600 people between one week and 95 years old from 29 countries.
The results show that infants have the highest metabolic rate by weight, and one-year-old children consume calories 50% faster than adults.
Researchers say it provides new insights into the popular belief that calorie burning peaks in the teenage years and 20s.
Even taking into account the baby’s weight and composition, their expenditure is much higher than expected
The results of the study also showed that the metabolic rate did not start to decline gradually until the age of 60 and beyond after being relatively stable from the 20s to 50s.
The research, titled “Daily Energy Expenditure in the Process of Human Life”, was published in the journal Science and is the result of the work of an international team of scientists including Professor John Speakman of the University of Aberdeen.
Professor Speakman, the senior author of the paper, said: “Even taking into account the baby’s weight and composition, their expenditure is much higher than expected.
“This may be partly because they also transitioned from being sedentary in the first few weeks of life to being truly active after a year or so.
“Furthermore, their resting metabolic rate has risen dramatically at the same time-possibly related to their amazing growth rate.
“Infant’s’fuel-guzzling’ metabolism may explain to some extent why children who have not eaten enough during this developmental window are less likely to survive and grow into healthy adults.
“After the initial surge in infancy, data showed that metabolism slowed by about 3% every year, until we were in our 20s when our metabolism became a new normal.”
Despite the rapid growth during adolescence, the researchers said that after controlling body size, the daily calorie requirement during adolescence did not increase.
Although there are several factors that can explain the thickening of the waist that often occurs during the golden age of our work, the results of the study show that changes in metabolism are not one of them.
According to the paper, energy expenditure in the 20s, 30s, 40s, and 50s is the most stable, and the metabolism will not drop again until after 60.
It added that this slowdown is gradual, only 0.7% per year, but people in their 90s need 26% fewer calories a day than middle-aged people.
Professor Herman Pontzer, Duke University North Carolina In the United States, he said: “We really think that adolescence will be different, but it is not the case.
“Middle age is another surprise. Someone may tell you that body weight “goes downhill” after the age of 30. Although there are several factors that can explain the thickening of waist circumference that often occurs during the golden age of our work, the results of the study show that the metabolism is Change is not one of the reasons.”
Due to cost reasons, most previous large-scale studies in this field are limited in scale, so several laboratories aggregate their data into a database for analysis.
In order to arrive at a figure for total daily energy expenditure, the scientists used a method called “double-labeled water”, which is a complex urine test believed to provide the most accurate results.
The researchers said that previous studies in this field mainly measured basic life functions, such as breathing, digesting food and pumping blood-this is equivalent to the calories needed to maintain life, and is estimated to account for about 50-70% of the total calorie consumption.
By combining data from many component studies, this paper reveals for the first time the changes in our metabolism throughout our lives, and the contribution to these changes in resting and active metabolism.
But they added that this usually doesn’t take into account the energy spent doing other things: from washing the dishes, walking the dog, exercising in the gym, or even just fidgeting.
Professor Speakman said: “By combining data from many component studies, this paper reveals for the first time the changes in our metabolism throughout our lives, as well as its contribution to changes in resting and active metabolism.
“It takes a lot of work to compile and manage the database, but now it is starting to bear fruit, we have seen these surprising results, and it’s all worth it.”
The research was supported by the National Science Foundation, the International Atomic Energy Agency, Japanese Multinational natural gas producers Taiyo Nippon Sanso and Sercon Corporation.
