austinjp already provided references, but I think it should be obvious that not every calorie ingested is a calorie digested. That's down to what types of bact

austinjp already provided references, but I think it should be obvious that not every calorie ingested is a calorie digested. That's down to what types of bacteria you have in your gut among other things, and then you have insulin screwing things up if you eat a high sugar diet. I hate the "calorie is a calorie" parroting, because while it's true, it ignores every other factor involved in digestion and energy usage. I've been logging my food intake for a few years now, and I have a pretty solid idea of what my resting metabolic rate is, how much I need to eat when I'm building muscle and so on. The fact is, when I eat the same amount as guys who are similar in build and height, I better be ready to bulk. I simply cannot eat the same number of calories as my peers and expect to not gain weight, which means either my body is more effective at digestion, or I'm more predisposed to storing fat than they are.