So I just went and donated blood again and durring the recovery period it occured to me that it takes quite a bit of work for your body to regenerate that lost blood volume and the actual blood cells. Regrowing that many cells seems like it would be fairly energetically intensive. So how many calories does producing all those new blood cells actually consume? Is there even a way to know that?
There is no good way to outpace calorie consumption with activity. It is far far easier for humans to consume usable calories than it is for us to spend them.
In our ancestors this meant that we were able to go a long time between good meals during times of scarcity and still survive, but today it just means that if you’re worried about calories you should start in the kitchen, not the gym