HUNGER, EATING AND HEALTH

three forms of energy: Lipids, Amino acids, Glucose

three types of energy storage: Fats (preferred, 85% of energy), Protein, Glycogen

  1. Cephalic Phase – controlled by the brain, initiated by sight, smell thought or expectations of food; causes controlled release of insulin; it ends when nutrients from food start to be absorbed into the bloodstream
  2. Absorptive Phase – nutrients from a meal are used to satisfy the immediate energy requirements, the excess is stored away
  3. Fasting Phase – all of the non-stored nutrients have been used up and the body is withdrawing energy from its reserves (fat) to meet the immediate energy requirements; it ends when the next cephalic stage begins

Role of insulin:

  • Promotes use of glucose as the primary energy source
  • Promotes the conversion of bloodborne fuels into forms that can be stored: glucose to glycogen and fat, amino acids into proteins
  • Promotes the storage of glycogen in the liver and muscle, fat in adipose tissue and proteins in muscle

Role of glucagon:

  • Promotes the release of fatty acids and using them as the primary fuel
  • Stimulates conversion of free fatty acids to ketones, which are used as energy sources by the muscles

Glugostatic theory – a person becomes hungry when their glucose levels drop significantly below their set-point

Lipostatic theory – every person has a fat set-point and deviations from it lead to changes in the levels of eating

Positive-Incentive Perspective - suggests that people are usually not driven to eat by an energy deficit but are drawn by the anticipated pleasure of eating.

Leptin is a hormone that helps with maintain a normal weight in long-term and inhibits the feeling of hunger.

Levels of insulin are positively correlated with body fat.

Treatment of Obesity

  1. Serotonergic Agonists - were shown to decrease food consumption, they seem to increase short-term satiety signals;

  2. Gastric bypass: surgical treatment that involves short-circuiting the normal path of food through the digestive tract so that its absorption is reduced

  3. Adjustable gastric band procedure: positioning a hollow silicon band around the stomach to reduce the flow of food, an advantage of this method is that the band can be removed

  4. Anorexia Nervosa:

  • Eating disorder resulting in underconsumption of food, which results in life threatening weight loss
  • The mortality rate is around 4%
  • High suicide rates

Anorexic compilations:

  • reduced metabolism
  • bradycardia (slow heart rate)
  • hypotension (low blood pressure)
  • hypothermia (low body temperature)
  • anemia (deficiency of red blood cells)
  1. Bulimia Nervosa
  • Eating disorder characterized by periods of not eating interrupted by bingeing (eating large amount of food in a short time period) and then purging
  • If bulimics are underweight, they are diagnosed as bingeing anorexics
  • Mortality rate is around 4%

Bulimic complications

  • Irritation and inflammation of the throat
  • Vitamin and mineral deficiencies
  • Electrolyte imbalance
  • Dehydration
  • Acid reflux

Relationship between Anorexia and Bulimia:

  • Might be variants of the same disorder
  • Existing treatments rarely work, usually only the short-term ones and relapse is common
  • Distorted body image
  • Both are comorbid with OCD and depression