It's a little more complicated because the body needs a lot of stuff besides calories, like essential amino acids, vitamins and minerals. If the body misses something, it keeps hungry until it gets it, regardless of how much calories come with it. This means that carefully selecting what to eat is important. Not only regarding the content of the food, but also regarding the microbiome in the gut. The microbiome extracts the minerals and vitamins from the food. The preservatives in one single McDonalds burger destroy the microbiome for 6 months. People then need tons of food to get the essential stuff.