• What evidence exists that would contradict the theory of a “set point” that regulates the body's
eating and energy intake?
◦ Majority of americans consume twice the daily required amount of calories each day
◦ Over half the population of the United States is considered clinically obese
◦ 3% of the american adolescent population are annorexic or bulimic
• What are the eight steps of digestion?
◦ 1. Food is chewed to break it up and is coated with saliva
◦ 2. Saliva coats the food and begins the process of digestion
◦ 3. Swallowing moves the food down the esophagus and to the stomach
◦ 4. The stomach serves primarily as a resevoire to hold undigested food until it can be broken
down into its constituent parts.
▪ Hydrochloric acid in the stomach begins breaking food down into its constituent
▪ Pepsin in the stomach begins the process of breaking proteins down into amino acids
◦ 5. Food passes from the stomach to the duodenum through the pyloric sphinctor, where
most of the absorbtion takes place
◦ 6. Digestive enzymes in the duodenum (primarily from the pancreas and gall bladder) break
proteins down into amino acids and carbohydrates/complex sugars into simple sugars.
▪ Amino acids and simple sugars are readily absorbed by the duodenum walls and are
transported immediately to the liver
◦ 7. Fats are emulsified (reduced to tiny droplets) by bile in the duodenum but cannot pass
through the lining like amino acids and simple sugars. Fat is transported out of the
duodenum via ducts in the duodenum wall and are taken to the lymphatic system.
◦ 8. The remaining water and electrolytes are absorbed from the waste in the large intestine
and the remainder is ejected from the anus
• What are the three ways in which food energy is delivered to the body? What are the three
forms of chemical energy the body is able to store?
◦ The body receives energy in the form of lipids, amino acids and glucose
◦ The body stores energy in the form of fats, glycogen and proteins
• What are the three phases of energy metabolism and their definitions?
◦ Cephalic phase
▪ Preparation to eat food
▪ Initiated by food-predictive cues such as the sight or smell of food
◦ Digestive phase
▪ Food has been eaten and energy is being absorbed
▪ Meal is meeting the body's current energy requirements and excess energy is being
stored for later use
◦ Fasting phase
▪ Energy is no longer being absorbed
▪ Energy is now being withdrawn from resources
▪ This phase ends when the following cephalic phase begins
• What are insulin and glucagon's relationship to the phases of energy metabolism?
◦ Insulin is high during the cephalic and digestive phases and glucagon is low
▪ High levels of insulin promotes the use of blood glucose as a source of energy
▪ Stores excess energy in the form of glycogen in the liver and muscles, proteins in the muscles and fat in adipose tissue
▪ Low levels of glycogen inhibit the transformation of glycogen to blood glucose, fat to
free fatty acids and protein to ketons
◦ Glucagon levels are high during the fasting phase and insulin levels are low
▪ High levels of glucagon promots the conversion of stored energy to usable energy –
converts glycogen to blood glucose, fat to free fatty acids and proteins to ketons
▪ Inhibits the body (but not the brain) from using blood glucose as a source of energy
▪ Inhibits the conversion of usable energy into storable energy (ie. Glucose to glycogen,
free fatty acids to fat, amino acids to proteins)
▪ Inhibits the storage of fat in adipose tissue
• What two theories emerged as an attempt to explain or support set-theories? Does the evidence
support or disclaim these theories?
◦ Lipstatic set point theory
▪ Theory that overall food intake and long-term hunger patterns are governed by a set
point in body fat
▪ Supported by the observation that most adults tend to have a stable body weight
throughout the majority of their life
◦ Glucostatic set point theory
▪ Theory that immediate hunger needs are dictated by changes in blood glucose levels
▪ As levels get low, we become hungry.As levels become higher we become satiated.
▪ Unsupported by evidence
• Individuals given a high calorie drink before a meal to increase blood sugar do not
consume less food than individuals not given the high calorie drink (and thus
without an increase in blood sugar)
• Rats require a substantial drop in blood sugar in order to induce noticeable hunger
effects (ie. To induce eating)
• What is the positive-incentive model?
◦ The positive-incentive model of eating describes eating as something we have evolved to
take pleasure in and crave
◦ The positive