Caloric Balance (Energy Balance)

Caloric balance describes how caloric intake relates to caloric expenditure — that is, the number of calories taken in from food and drink versus those expended by basal metabolism and voluntary activity. The energy-balance equation states this relationship mathematically as:

Caloric Intake = Caloric Expenditure

In nutrition and exercise circles the word "calorie" is commonly used to mean what is actually a kilocalorie (kcal). See kilocalorie for the formal definition.

Three states can exist between intake and expenditure:

• Isocaloric balance — intake and expenditure are equal; tissue mass neither increases nor decreases. Example: a person who consumes an average of 2,500 kcal/day and expends 2,500 kcal/day is in balance.
• Positive caloric balance — intake exceeds expenditure; excess energy is stored as adipose tissue (see positive-caloric-balance).
• Negative caloric balance — expenditure exceeds intake; a caloric deficit exists and stored fat is used for energy (see negative-caloric-balance).

People in physical-activity and weight-reduction programs must understand that balance between calories taken in and calories expended is what keeps body weight stable.

• Energy-balance equation: Caloric Intake = Caloric Expenditure.
• Isocaloric example: 2,500 kcal in and 2,500 kcal out → no change in tissue mass.
• Expenditure = basal metabolism + voluntary activity.

• kilocalorie — defines the unit used in the equation.
• positive-caloric-balance — intake > expenditure.
• negative-caloric-balance — expenditure > intake.
• exercise-and-calories — the source page this concept appears on.
• cardiorespiratory-guidelines — total work estimated by caloric expenditure.