Question

A friend is very overweight and describes to you his method of weight loss. He fasted completely for 1 week and is now on a strict diet of 400 to 600 kcal/day under a physician’s supervision. The food energy comes from a liquid formula, which he drinks for breakfast. He skips lunch and eats a small dinner of 3 ounces of protein, ½ cup of vegetables, 1 cup of fruit, and 2 starch items (a small potato, a piece of bread). He has lost approximately 25 lb in 12 weeks.

Based on your knowledge of energy metabolism, answer the following questions he poses.

1. During the fasting stage, what were the likely sources of energy for the body’s cells?
2. What metabolic adaptations occurred to provide glucose for the nervous system?
3. When he began eating 400 to 600 kcal/day, how did the metabolic processes in his body most likely change from the fasting state?

Answer 1

1. During fasting stage , the stored glucose which is in the form of glycogen is released in to the blood stream and supplies energy to the cells.

The food we eat will be converted in to glucose, where as the excess glucose will be converted in to glycogen and stored on the liver. When ever the body requires glucose specially during the fasting stage, the stored glycogen is converted in to glucose thus, supplying energy to the body cells.

2. Once after the glycogen stored in the liver was totally released out, now the liver start producing ketones bodies. These ketones bodies provides energy to the nervous system after 3 days of fasting.So because of this production of ketone bodies , brains requirement of 80 gms of glucose will be cut down to 30 gms per day.After several days even the protein depletion takes place which ultimately destroys the muscle mass of skeletal system and thus damaging the brain which leads to arrest.

3. Once after fasting when he started to consume 400 to 600 kcal per day, his body is going to produce lesser amounts of insulin storage to convert in to glucose.So because of this his body adapts to produce more amount of ketone bodies thus loosing his muscle mass.