Calorie balance describes the relationship between the energy taken in through food and the body's actual energy expenditure. If intake permanently exceeds expenditure, this is called a calorie surplus, and in the opposite case a calorie deficit. If both values are roughly balanced, body weight remains stable over a longer period.
Total energy expenditure is made up of the basal metabolic rate, the activity-related energy expenditure from movement, and the energy used for digestion. These values can only be estimated approximately, as there are individual differences in metabolism.
Relevance for nutrition and sport
In nutrition science, calorie balance is considered the central factor for weight change, even though the composition of the diet, such as the protein share, also plays a role for satiety and body composition. A moderate deficit is often regarded as gentler for weight loss than a very large deficit.
For muscle building, on the other hand, a slight surplus combined with strength training is often cited. A permanently one-sided calorie balance in either direction can have a negative effect on performance and well-being. The guide protein for weight loss explains how to set up a calorie deficit sensibly. Supplements do not replace a balanced diet but can at most complement it sensibly.