Are all calories created equal? Your gut microbes don’t think so.

The basic calorie in/out concept always struck me as obviously too simple.

When I found out that the way we determined how many calories was in a given food ingredient, was by actually burning it and measuring the energy output, I knew whole concept was flawed. Our bodies simply don't "burn" food like that. We don't shit ash. There can't be a simple 1:1 correlation.