Problem 59P

An adult eats food whose nutritional energy totals approximately 2.2 × 103 Cal per day. The adult burns 2.0 × 103 Cal per day. How much excess nutritional energy, in kilojoules, does the adult consume per day? If 1 lb of fat is stored by the body for each 14.6 × 103 kJ of excess nutritional energy consumed, how long will it take this person to gain 1 lb?

Solution 59P

Total energy gained per day=2.2103 cal

Energy burned per day=2.0103 cal

Excess nutritional energy gained by the adult=Total energy gained per day-Energy burned per day =2.2103 cal -2.0103 cal =0.2103 cal

We know that 1 cal=4.184 J

So the excess nutritional energy in KJ gained by the adult=4.1840.2103 J

=0.836J103 KJ

Given that consumption of 14.6103 KJ results in the deposition of 1lb of fat

Suppose consumption of 836KJ of energy for x days results in deposition of 1lb of fat(corresponding to 14.6103 KJ )

(836J)x=14.6103 J

Then x==17.464

Thus it will take 17.4 days