The study which was conducted on 6,400 participants, from eight days old up to age 95, in 29 countries, reveals that metabolism stays 'rock solid' throughout mid-life.
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It peaks at the age of one, remains stable from 20 to 60 and then inevitably declines. Researchers opined that the findings gave surprising new insights about the body.
Ripped muscles
Metabolism is the essential chemistry needed to keep the body going. The bigger the body, whether that is ripped muscles or too much belly fat, the more energy it will take to run.
So the researchers made slight changes in their measurements, adjusting for body size, to compare people's metabolism 'pound for pound.'
The study, published in the journal Science, discovered four phases of metabolic life:
- Birth to age one, when the metabolism shifts from being the same as the mother's to a lifetime high 50% above that of adults.
- A gentle slowdown until the age of 20, with no spike during all the changes of puberty.
- No change at all between the ages of 20 and 60.
- A permanent decline, with yearly falls that leave metabolism 26% lower by the age of 90 than in mid-life.
Prof John Speakman, who was one of the researchers from the University of Aberdeen said:
It is a picture we've never really seen before and there is a lot of surprises in it.
The most surprising thing for me is there is no change throughout adulthood; if you are experiencing mid-life spread you can no longer blame it on a declining metabolic rate.
Childhood malnutrition
Other revelations came from what the study did not find. There was no metabolic rise during either puberty or pregnancy and no slowdown around the menopause.
The high metabolism in the first years of life also goes to show how important it is in development and why childhood malnutrition can have lifelong consequences.
Prof Herman Pontzer, from Duke University, told BBC News:
When people talk about metabolism, they think diet and exercise; but it is deeper than that, we are actually watching your body, your cells, at work.
They are incredibly busy at one year old and when we see declines with age, we are seeing your cells stopping working.
