Lawrence is an overweight male adult embarking on his first attempt at weight loss. He has heard that in order to lose one pound of fat per week, he should cut kilocalories by 500 kilocalories per day from his normal intake. What is the theory behind the notion that a 500-kilocalorie daily deficit promotes weight loss of one pound of fat per week?

3,500-calorie rule

Explanation:

The burning of fat provides about 9 kcal/g of fat and one pound of weight equals 454 g, therefore, one pound of fat contains 4086 kcal.

However, the research on the burning of fat indicates that about 3500 kcal are burned as the fat contains only 87% of the lipid which is burned and therefore 87% of 454 will provide 3,500 kcal.

So according to the 3,500 kcal rule, if one pound of fat has to be burned in one week therefore 3500/7 kcal has to burn daily.

Thus, 500 kcal according to the 3,500 kcal rule will be burned.