Energy Homeostasis and Nutrition

Energy Homeostasis

• Definition: Energy intake is matched to energy expenditure.
• Energy Intake: Depends on the amount of food consumed.
• Energy Expenditure: Depends on:
  • Basal metabolic rate (BMR)
  • Thermogenesis from non-exercise
  • Food-induced thermogenesis

Hypothalamus and Food Regulation

• Centers in Hypothalamus:
  • Feeding (hunger) center
  • Satiety center
• Role of Hormone Leptin:
  • Acts on hypothalamus
  • Increases energy expenditure
  • Inhibits circuits that stimulate eating
• Other Influences:
  • Glucose, amino acids, lipids
  • Body temperature, GI tract distension
  • Cholecystokinin (CCK)

Healthy Diet Recommendations

• Eat a variety of foods
• Maintain a healthy weight
• Choose low-fat, low-saturated fat, low-cholesterol foods
• Eat plenty of vegetables, fruits, and grains
• Use sugar, salt, and sodium in moderation
• Limit alcohol consumption

Dietary Guidelines

• MyPlate/Healthy Eating Plate:
  • Replaced the food guide pyramid
  • Visualizes portions of food groups: fruits, vegetables, grains, proteins

Minerals

• Inorganic Substances:
  • Make up ~4% of body weight
  • Functions:
    • Bone formation (calcium, phosphorus)
    • Enzymatic reaction regulation (calcium, iron, manganese, magnesium)
    • Buffer systems, osmosis regulation, nerve impulse generation

Vitamins

• Organic Nutrients:
  • Maintain growth and normal metabolism
  • Function as coenzymes
  • Cannot be synthesized by the body
  • No single food contains all vitamins

Types of Vitamins

• Fat-soluble: A, D, E, K
  • Stored in liver
  • Require emulsification for absorption
• Water-soluble: B vitamins, Vitamin C
  • Absorbed with water
  • Excreted in urine if in excess

Vitamin Deficiencies

• Beriberi: Lack of Thiamine (B1)
  • Symptoms: weakness, pain, sensory impairment
• Scurvy: Lack of Vitamin C
  • Symptoms: anemia, gum disease, skin hemorrhage
• Rickets: Lack of calcium, phosphorus, or Vitamin D
  • Symptoms: weak and soft bones

Antioxidants

• Includes vitamins C, E, beta-carotene
• Inactivate oxygen free radicals
• Protect against cancer, aging, cataracts, atherosclerosis

Vitamin Supplements

• Recommended for certain groups:
  • Women with heavy menstrual bleeding
  • Pregnant or nursing women (iron, calcium, folic acid)
  • Strict vegetarians (B12)
  • All adults (calcium, antioxidants)

Eating Disorders

• Obesity:

  • Defined as body weight >20% above standard
  • Risk factor for various diseases

• Anorexia Nervosa:

  • Mental disorder, fear of obesity
  • Symptoms: extreme weight loss, pale skin, amenorrhea

• Bulimia Nervosa:

  • Binging and purging disorder
  • Symptoms: dehydration, GI issues, dental problems

• Pica:

  • Eating non-nutritive substances
  • Common in children, pregnant women, developmental disorders
  • Risks: infection, nutritional deficiency, intestinal blockage

Goals of the Lecture

• Describe hypothalamic functions: thermostat, satiety center, leptin, and antioxidants
• Define BMR, core temperature, shell temperature, hypothermia, fever
• Outline basic healthy eating guidelines
• Name and describe functions of several minerals
• Define vitamins and list fat- and water-soluble types
• Describe symptoms and causes of beriberi, scurvy, and rickets
• Identify those who should consider vitamin supplements
• Discuss eating disorders: anorexia nervosa, bulimia nervosa, and pica