Physics Fat Metabolism

Question

When you jog, most of the food energy you burn above your basal metabolic rate (BMR) ends up as internal energy that would raise your body temperature if it were not eliminated. The evaporation of perspiration is the primary mechanism for eliminating this energy.

The metabolism of 1 gram of fat generates approximately 8.90 kcal of energy and produces approximately 1 gram of water. (The hydrogen atoms in the fat molecule are transferred to oxygen to form water.) What fraction of your need for water will be provided by fat metabolism? 

_______%

Answer 1

Assumptions:

1600 kcal/day basal energy expenditure

2.5 L/day baseline water requirements

Starvation state and all energy is provided by fat.

1600/8.9 = 180 grams of water

180/2500 = 0.072 = A maximum of 7.2% of baseline water requirements could be provided by fat metabolism.