What is a common effect of being in a calorie deficit?

Being in a calorie deficit means that the body is consuming fewer calories than it expends, which triggers a metabolic response. In this state, the body begins to utilize stored energy to meet its needs. This stored energy primarily comes from fat reserves, which leads to fat loss. When the body requires more energy than it is taking in from food, it must tap into its energy stores, thus facilitating the mobilization and reduction of fat tissue.

In addition to the direct metabolic effects of a calorie deficit leading to fat loss, the body can also undergo some changes in muscle mass. However, the primary and most desired outcome when discussing calorie deficit and weight loss is typically fat loss. This is one of the fundamental concepts in nutrition and weight management, making it clear why fat loss is closely associated with being in a calorie deficit.