Energy balance is the relationship between energy input (calories consumed through food and drink) to energy output (calories used by the body for our energy requirements) being equal.
This relationship dictates whether weight is lost, gained, or remains the same.
If we consume more energy from foods than what we need, the unused energy will be stored as fat. When too much weight is gained this can increase our risk of developing obesity and other related disorders.
If we balance our energy from foods with the energy we use through activity this will result in a constant weight being maintained.
If we use more energy than we consume, this will lead to weight loss due to fat stores being used up quickly by the body.