That’s right—that fat on your body contains stored energy, ready to be used when there isn’t enough provided by the food you eat. Adipose tissue (body fat) provides some protection and insulation for your body, but at the end of the day, it’s nothing more than stored energy. Eating more calories does not necessarily cause fat gain. If you’re an athlete or work a physical job, you need to be eating extra calories just to function.
The problem lies in excess calorie consumption. If you regularly eat more calories than your body burns in a day, that excess energy needs to go somewhere, and most of it will be stored as body fat. If you eat fewer calories than your body needs, you’ll end up using some of your stored fat for energy, decreasing your body fat stores. Body fat loss or gain ultimately comes down to calorie balance, and whether you’re eating more than your body needs (fat gain), or less than your body needs (fat loss).