If we’re going to talk about how exercise impacts metabolism, we need to start with a clear explanation of what exactly “metabolism” means. The official definition of metabolism is the total of all chemical processes that convert food into the fundamental chemicals used by the body for energy. Everything we eat (and drink) that has calories in it goes through a series of complicated biochemical processes that break down the food (using that to mean anything ingested) into usable energy. This energy is then used for keeping our bodies alive; that’s our “basal metabolic rate” (BMR), the baseline, minimal amount of calories (food) we’d need if we were in a coma or spent all day every day lying in bed. BMR, also called Basal Energy Expenditure (BEE) includes breathing, maintaining body temperature and all the other internal body regulating things we don’t think about.