Eli5: the larger the creature the slower the metabolism; so why do our metabolisms speed up when we gain weight?

Question

Eli5: the larger the creature the slower the metabolism; so why do our metabolisms speed up when we gain weight?

In: 4

Answer 1

With regards to “the larger the creature the slower the metabolism”; that only applies to calories per pound; not total calories spent. For example, a hummingbird – often used as a high-metabolism animal – consumes as much as 8 calories per day for a 3 gram body weight: about 2 calories per gram. In contrast, an adult human at about 60 000 grams only consumes about 3000 calories – about .05 calories per gram. And adding muscle makes you more efficient: 1000 grams of muscle only adds about 5 calories per day – .005 calories per gram, or about 1/10 of what baseline is (which is high because the human brain uses a huge amount of extra calories).