Because you’re in a calorie deficit. But are you losing muscle? That’s what matters. Your body prioritizes muscle cells over fat cells WHEN you workout often. But your body is limited by genetics. There is a certain number of muscle cells you can grow in a given week. Eating more DOES NOT change the number of muscles you can grow. Otherwise, the key to becoming as big as Arnold would be to just workout and eat like an obese American at McDonald’s.