Human being is hungry when

Options

A. Food cannot meet energy requirement
B. Stomach is empty
C. Food can meet energy requirement of the body
D. Food has been digested

Answer

To answer the question "Human being is hungry when," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hunger**: Hunger is a physiological signal that indicates the need for food. It is primarily regulated by hormones produced in the gastrointestinal tract.

2. **Role of the Stomach**: The stomach is a key organ in the digestive system that temporarily holds food. When it is empty, it triggers specific hormonal responses.

3. **Hormone Production**: When the stomach is empty, it produces a hormone called **ghrelin**. This hormone is often referred to as the "hunger hormone."

4. **Signal to the Brain**: Ghrelin travels through the bloodstream to the brain, where it sends signals that stimulate the sensation of hunger. This is the body's way of indicating that it needs food.

5. **Other Hormones**: Once food enters the stomach, it expands, and the walls of the stomach are stretched. This leads to the release of another hormone called **leptin**, which signals to the brain that the body is no longer hungry.

6. **Conclusion**: Therefore, the correct answer to the question is that a human being feels hungry when the stomach is empty. This is the point at which ghrelin is produced, signaling the need for food.

### Final Answer:
Human beings feel hungry when the stomach is empty.

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