An adult eats food whose nutritional energy totals approximately 2400 Cal per day. The adult burns 2200 Cal per day.

Question

An adult eats food whose nutritional energy totals approximately 2400 Cal per day. The adult burns 2200Cal per day. If 1 lb of fat is stored by the body for each 14.6×103kJ of excess nutritional energy consumed, how long will it take this person to gain 1 lb?

Express your answer using one significant figure.

Answer 1

We will use the calorie conversion factor:

1 Cal = 4.186 kJ

The adult has an energy total of 2400 Cal per day but only consumes 2200. Therefore, there will be an excess of 200 Cal. Overtime, this excess will accumulate .

First, let's convert 200 Cal to kJ then divide this number by the conversion for a pound of fat.

200 Cal * 4.186 kJ/1 Cal = 837.2 kJ

14.6 x 10³ kJ = 14600 kJ/837.2 kJ = 17.43 days

It will take approximately 17 days to gain one pound. As a side day, this is the recommend time expert gives to lose weight in a healthy way.