Which of the following statements is false?
a. A healthy human has enough stored fat to supply calories for several weeks.
b. An increase in leptin levels leads to an increase in appetite and weight gain.
c. The interconversion of glucose and glycogen takes place in the liver.
d. After glycogen stores are filled, excessive calories are stored as fat, regardless of their original food source.

Verified step by step guidance

1. Step 1: Begin by analyzing each statement individually to determine its validity based on biological principles.
2. Step 2: Evaluate statement (a): 'A healthy human has enough stored fat to supply calories for several weeks.' This is true because fat is a long-term energy storage molecule, and humans can survive on stored fat during periods of caloric deficit.
3. Step 3: Evaluate statement (b): 'An increase in leptin levels leads to an increase in appetite and weight gain.' This is false because leptin is a hormone produced by adipose tissue that typically suppresses appetite and signals the brain to reduce food intake when fat stores are sufficient.
4. Step 4: Evaluate statement (c): 'The interconversion of glucose and glycogen takes place in the liver.' This is true because the liver plays a central role in glycogen storage and breakdown, converting glucose to glycogen (glycogenesis) and glycogen back to glucose (glycogenolysis) as needed.
5. Step 5: Evaluate statement (d): 'After glycogen stores are filled, excessive calories are stored as fat, regardless of their original food source.' This is true because once glycogen storage capacity is reached, surplus calories are converted into triglycerides and stored in adipose tissue, regardless of whether the calories come from carbohydrates, proteins, or fats.

Key Concepts

Leptin and Appetite Regulation

Leptin is a hormone produced by adipose (fat) tissue that helps regulate energy balance by inhibiting hunger. Higher levels of leptin typically signal the brain to reduce appetite and increase energy expenditure. An increase in leptin levels generally leads to decreased appetite, not an increase, making this concept crucial for understanding the relationship between hormones and weight management.

Glycogen Storage and Utilization

Glycogen is a stored form of glucose primarily found in the liver and muscles. When the body requires energy, glycogen can be converted back into glucose through a process called glycogenolysis. Understanding how glycogen is synthesized and broken down is essential for grasping how the body manages energy reserves and responds to dietary intake.

Energy Storage and Conversion

The body stores excess energy from food in the form of glycogen and fat. Once glycogen stores are full, any additional calories consumed are converted into fat through lipogenesis. This process highlights the body's ability to adapt to varying energy intakes and is fundamental for understanding weight gain and metabolic health.