During prolonged fasting,the sequence of organic compound used by body is

Options

A. First carbohydrates, next fats and lastly proteins
B. First fats, next carbohydrates and lastly proteins
C. First carbohydrates, next proteins and lastly lipids
D. First Proteins, next lipids and lastly carbohydrates

Answer

**Step-by-Step Solution:**

1. **Understanding Energy Sources**: The body primarily uses three types of organic compounds for energy: carbohydrates, fats, and proteins. Each of these compounds serves as a source of ATP (adenosine triphosphate), which is the energy currency of the cell.

2. **Carbohydrates as the First Source**: During normal conditions, carbohydrates are the first source of energy. They are broken down into glucose, which is then converted into ATP. If there is an excess of glucose, it is stored as glycogen in the liver and muscles.

3. **Glycogen Utilization During Fasting**: When fasting begins and glucose levels drop, the body utilizes glycogen stores. The hormone glucagon facilitates the conversion of glycogen back into glucose, which can then be used to produce ATP.

4. **Fats as the Second Source**: Once glycogen stores are depleted (usually after about 24 hours of fasting), the body shifts to using fats as the next source of energy. Fats are broken down into fatty acids and glycerol, which can also be converted into glucose or directly used to generate ATP.

5. **Proteins as the Last Resort**: If fasting continues for an extended period and both glycogen and fat stores are exhausted, the body will start to break down proteins. This process involves the catabolism of muscle tissue and other proteins to release amino acids, which can be converted into glucose or used directly for energy.

6. **Conclusion**: Therefore, the sequence of organic compounds used by the body during prolonged fasting is: first carbohydrates, then fats, and lastly proteins.

**Final Answer**: The correct sequence is: **First Carbohydrates, then Fats, and lastly Proteins.**

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