Eli5 why do some of us have fast metabolism? In this respect, why is the body constitution different for each?
In: Biology
There is variability between individuals for many enzymes, hormones (and their receptors), and other chemical processes in your body.
Some of these variations work faster, more efficiently, or otherwise “better” than others.
These differences add up to a wide range of metabolic rates, and likelihood to put on fat/muscle etc.
In the same way that some of us have different eye color or hair color, these traits arose likely from an accident. Some genetic mutation thousands of years ago. To date there has been no outside stressor which would make having a fast metabolism better than a slow one or vice versa. No disease or predator or the availability of prey has been dependent on this trait, therefore one is not more likely to survive and reproduce than the other, leading to individuals who have different metabolisms to walk alongside one another. Should a crazy freak event happen which would make a fast metabolism more likely to reproduce than a slow one, then over a long period of time we would see a decline in slow metabolism people until the gene becomes phased out entirely.
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