Appetite and Diet

• Appetite is controlled by a centre in the hypothalamus
• Hormones produced in the pancreas, stomach, intestines, and adipose tissue send messages to the appetite control centre of the brain (within the hypothalamus)
• Hormonal signals trigger feelings of hunger (promote feasting) or satiety (promote fasting)
• Ways hormones are triggered:

  • Stretch receptors in the stomach and intestine become activated when ingested food distends these organs
  • Adipose tissue releases hormones in response to fat storage
  • The pancreas releases hormones in response to changes in blood sugar concentrations
• Hormones that trigger hunger response:

  • Ghrelin (from stomach)
  • Glucagon (from pancreas)
• Hormones that trigger satiety response:

  • Leptin (from adipose tissue)
  • CCK (from intestine)
• Overweight individuals are more likely to suffer hypertension and type II diabetes
• Starvation can lead to breakdown of body tissue
• Changes in diet and appetite control may result in individuals over-indulging or under-indulging during meals
• Clinical obesity (BMI > 30) is caused by:

  • Increased energy intake (overeating or diets rich in fats and sugars)
  • Decreased energy expenditure (less exercise due to a sedentary lifestyle)
• Excess weight can lead to hypertension (abnormally high blood pressure)
• High cholesterol diets can lead to atherosclerosis, narrowing blood vessels and contributing to raised blood pressure
• Type II diabetes occurs when fat, liver, and muscle cells become unresponsive to insulin (insulin insensitivity)
• Starvation leads to significant weight loss as body tissue is broken down for energy
• Anorexia nervosa can lead to the breakdown of heart muscle, making heart disease the most common cause of death in severe cases
• In severe anorexia, the heart may develop dangerous arrhythmias and become physically diminished in size