13.5 Biological Explanations for Obesity

• What is the clinical definition of obesity based on BMI?

  ≥ 30 kg/m²
• BMI is calculated using the formula: \frac{weight \space \in \space kg}{(height \space \in \space m)^{2}}</latex>
• A high waist circumference indicates abdominal fat accumulation.
• What waist circumference is considered high for males?

  > 102 cm
• What waist circumference is considered high for females?

  > 88 cm
• The hormone leptin signals satiety to the brain, reducing appetite
• What does the MC4R gene regulate in the hypothalamus?

  Energy intake and expenditure
• Mutations in the leptin gene lead to reduced leptin sensitivity.
• Match the genetic factor with its function and impact on obesity:

  Leptin ↔️ Signals satiety; reduced sensitivity leads to overeating

  MC4R Gene ↔️ Regulates energy intake; mutations increase food intake
• Which hormone stimulates appetite and is released by the stomach?

  Ghrelin
• Insulin resistance can lead to increased blood glucose levels, triggering more insulin release and fat storage
• Match the hormone with its function and impact on obesity:

  Leptin ↔️ Signals satiety; decreased sensitivity leads to overeating

  Ghrelin ↔️ Stimulates appetite; elevated levels increase food intake

  Insulin ↔️ Regulates blood sugar; resistance promotes fat storage
• What is the function of leptin in regulating body weight?

  Signals satiety
• What is the function of ghrelin in regulating body weight?

  Stimulates appetite
• Dysregulation of ghrelin can contribute to obesity.
• Leptin is produced by fat cells.
• What hormone stimulates appetite?

  Ghrelin
• Leptin, produced by fat cells, signals satiety
• Dysregulation of leptin or ghrelin can contribute to obesity.
• Match the brain area with its function:

  Hypothalamus ↔️ Regulates hunger and satiety

  Ventromedial Hypothalamus (VMH) ↔️ Signals fullness

  Lateral Hypothalamus (LH) ↔️ Stimulates appetite
• What neurotransmitter is released in the reward system to reinforce eating behaviors?

  Dopamine
• The hypothalamus regulates hunger and satiety
• What is the BMI threshold for obesity?

  ≥ 30 kg/m²
• A waist circumference > 102 cm for males indicates obesity.
• Match the genetic factor with its function:

  Leptin ↔️ Signals satiety

  MC4R Gene ↔️ Regulates energy intake and expenditure
• What hormone is released by the stomach to stimulate appetite?

  Ghrelin
• The ventromedial hypothalamus signals fullness
• What genetic factor is associated with reduced leptin sensitivity?

  Leptin
• Biological explanations for obesity often neglect environmental factors.