Snapshot 1:- About Energy

Snapshot 1:- Energy.

Our body uses energy to fuel Cellular metabolism, especially the major organs like brain, heart, liver and gastrointestinal tract, and for physical activity.

 Carbohydrates and proteins each provide 17 kJ/g (4.1kcal) of metabolizable energy intake, with fats and alcohol providing 37  kJ/g and 29 kJ/g respectively.

 Our appetite mechanism usually allows us to match energy intake to energy expenditure so that we maintain a healthy body weight, but when we overeat, the excess energy intake is stored as fat. Overweight people should aim for an energy intake slightly less than their energy expenditure so that their energy deficit is met from their body fat, helping them to achieve a lower, healthy body weight. 

Our total energy expenditure (TEE) depends on the rate at  which the body expends energy at rest (basal metabolic rate – BMR) and our physical activity level (PAL), and this is expressed by the relationship: 

TEE = PAL x BMR. 

BMR can be predicted from body weight, sex and age, and PAL varies with lifestyle from 1.35 in sedentary people to 2.5 for the very active. At an average PAL of 1.63, men and women of average height need 11 MJ and 9 MJ of food energy each day for a healthy body weight.