Energy balance describes the dynamic relationship between the energy an individual consumes (calories [IN]), the energy their body burns (calories [OUT]), and the storage of excess energy (calories) as body fat. When energy intake consistently exceed energy needs (calories [IN] > calories [OUT]), body fat increases. Conversely, when energy needs consistently exceed energy intake (calories [OUT]> calories [IN]), body fat decreases. When calories [IN] = calories [OUT], there is no change in body fat.
Although energy balance may seem a simple concept, for most people attaining and maintaining a healthy weight requires actively managing both the calories [IN] and the calories [OUT] sides of the energy balance equation. This includes understanding individual caloric needs and the role of regular physical activity in regulating body weight and maintaining overall good health. It also includes gaining knowledge about the caloric content of foods and beverages, as well as and adopting behaviors like portion control and calorie budgeting to help manage energy intake.