...e melhor compreendida:
http://www.mirror.co.uk/science/scientists-think-know-what-causes-8790932
Citando:
"Prof Wilkin said calories are burnt off in two ways - voluntary spend through physical activity and the much larger involuntary spend, simply to stay alive.
Thinking, keeping blood warm, and keeping the heart, liver and kidneys working together use up to 1,600 calories per day in adolescence."
(...)
"Burning calories uses a fixed amount of oxygen, so the children rested in a sealed canopy and their oxygen consumption was measured over a period of time, to enable researchers to calculate their calorie use from the amount of oxygen consumed."
(...)
"Prof Wilkin said: "When we looked for an explanation for the rising obesity in adolescence, we were surprised to find a dramatic and unexpected drop in the number of calories burned while at rest during puberty.
"We can only speculate as to why, but it could be a result of an evolutionary trait to save calories for growth that may now contribute to a dangerous rise in adolescent obesity in cultures where food is in abundance.
"It could be that we have evolved to preserve calories to ensure we have enough to support changes in the body during puberty, but now they have sufficient calories each day, the drop in spend means excess weight gain.""