Iran Press/ Sci & Tech: Everyone knows conventional wisdom about metabolism: People put pounds on year after year from their 20s onward because their metabolisms slow down, especially around middle age. Women have slower metabolisms than men. That's why they have a harder time controlling their weight. Menopause only makes things worse, slowing women's metabolisms even more.
All wrong, according to a paper published Thursday in Science. Using data from nearly 6,500 people, ranging in age from 8 days to 95 years, researchers discovered that there are four distinct periods of life, as far as metabolism goes. They also found that there are no real differences between the metabolic rates of men and women after controlling for other factors, The New York Times reported.
The findings from the research are likely to reshape the science of human physiology and could also have implications for some medical practices, like determining appropriate drug doses for children and older people.
"It will be in textbooks," predicted Leanne Redman, an energy balance physiologist at Pennington Biomedical Research Institute in Baton Rouge, La., who also called it "a pivotal paper."
But the findings' implications for public health, diet and nutrition are limited for the moment because the study gives "a 30,000-foot view of energy metabolism," said Dr. Samuel Klein, who was not involved in the study and is director of the Center for Human Nutrition at the Washington University School of Medicine in St. Louis. He added, "I don't think you can make any new clinical statements" for an individual. When it comes to weight gain, he says, the issue is the same as it has always been: People are eating more calories than they are burning.
All of the research centers involved in the project were studying metabolic rates with a method considered the gold standard — doubly labeled water. It involves measuring calories burned by tracking the amount of carbon dioxide a person exhales during daily activities.
Central to their findings was that metabolism differs for all people across four distinct stages of life.
There’s infancy, up until age 1, when calorie burning is at its peak, accelerating until it is 50 percent above the adult rate.
Then, from age 1 to about age 20, metabolism gradually slows by about 3 percent a year.
From age 20 to 60, it holds steady.
And, after age 60, it declines by about 0.7 percent a year.
214
Read More:
Study: Healthy diet prevents Metabolic syndrome in children
