Abstract
It is known that matter cannot be created or destroyed in the universe, which has proposed that lower calorie expenditure be associated with an increase in body weight.
Driven by this idea, an explanation that dominated for a long time was the one that held that those with faster metabolisms burn more calories and those with slower metabolisms burn fewer calories. Thus, following intuition, it was proposed that those who have slow metabolisms are prone to gain weight compared to those who have fast metabolisms.
That position seems to make sense until it is confronted with experimental evidence. The most complete study on metabolism to date (you can check the link) supports a different panorama.
The study, in summary, suggests that metabolic acceleration would not influence weight gain in adulthood. The study found that human metabolism would only accelerate until the first year of biological life (+-), then begin to decline until adulthood where it stabilizes, until it declines again in old age (after 60 years +-)
That is to say, the experimental data from this study suggest that when the metabolism is faster, the most weight is gained, and when it slows down, the weight is lost. Children gain weight rapidly as they grow and the elderly begin to lose weight.
This evidently seems contradictory to the hypothesis of metabolic acceleration. Counterintuitive for some.
However, the explanation is simple. Children gain weight despite their faster metabolism because they are carrying out more anabolic processes, on the other hand, the elderly lose weight despite having an increasingly slower metabolism because they are carrying out more catabolic processes.
So this study shows that when calories are used preferably through anabolic, rather than catabolic, pathways, weight is gained.
It would then not be so much about how many calories you burn, but how you burn them. Even if you spend more calories than another person, if those calories are used in anabolic processes they will make it easier for you to gain weight.
This proposal, which coincides with current evidence, would explain what the realistic participation of metabolism in the issue of body weight would be.