Caloric restriction (CR) is explored to limit the caloric intake without malnutrition. CR can affect the levels of various metabolites in organism, such as lipids, free fatty acids, ketones, bile acids and amino acids, etc, and is thought being able to extend the lifespan, postpone and reduce the incidence of age-related disorders (e.g., type 2 diabetes, cancer and cardiovascular diseases). These effects are mainly attributed to the role of CR in energy metabolism. The mechanism of CR on energy metabolism is closely related to biological clock, hormonal production, gastrointestinal flora and inflammation. Here we briefly review the effects and mechanism of CR on energy metabolism.