Energy Balance and Body Weight

Your 24-hour energy expenditure is the total amount of energy expended in a 24 hour period and is made up of 3 main components: resting energy expenditure, thermic effect of food, and physical activity energy expenditure.

REE - the energy expended at rest to keep vital organ systems functioning - and is about 65% of our total energy expenditure in a day.

Thermic effect of food - the energy expended by the body to digest, absorb, and metabolize food; it accounts for about 10% of your energy expenditure.

Physical activity - only accounts for about 25% of your daily energy expenditure.

This info is for most North Americans.

Of course if you increase your physical activity it would take up more of your total energy expenditure for the day. Also increase in lean body mass increases REE since lean body mass burns more calories than adipose tissue.