Energy Requirements

The basal metabolic rate (BMR) is the energy required to maintain physiology at rest., and is proportional to lean body weight and body surface.

Men burn 1.0 cal/hr/kg and women burn 0.9 cal/hr/kg. This works out to about 1800 Cal for a man of 70 kg and 1300 Cal for a women of 50 kg.

BMR is higher in men, the young, overweight individuals, or those with hyperthyroidism.

BMR accounts for 60-70% of energy use.

Brain and liver account for 40% of BMR but only 4% of body weight. Muscle uses 25% of BMR bu comprises 40% of body weight.

Physical activity affects energy usage depending on activity, but is normally 15-20% or up to 50% in athletes.

Digestion and absorption of food accounts for 5-10% of energy expenditure, with fat requiring the lowest and protein the highest.