Chapter 14 (new)

Where does digestion begin?

In the mouth, with chewing and saliva

What role do enzymes in saliva play?

they begin breaking down food before it reaches the stomach

Where does most nutrient absorption occur?

in the small intestine

What does the large intestine mainly absorb?

liquid

What are the three main uses of energy from food?

processing food, basal metabolism, and physical activity

What percent of your energy from food does processing food take?

8%

What percent of your energy from food is used for your basal metabolism?

55%

What percent of your energy from food is used for physical activity?

12-13%

What controls when and how much we eat?

hormones - more than 30 affect eating behavior

What was the goal of the Keys starvation experiment?

reduce participants weight by 25%

What were the psychological effects of the Keys starvation experiment?

participants became irritable and aggressive

What happened after the Keys starvation experiment ended?

participants regained or exceeded their original weight

How does metabolism adjust during dieting?

basal metabolism decreases to reserve weight

What was shown in the brownell et al. rat study?

repeated weight cycling made metabolism more efficient and weight regain faster

How does caloric restriction affect metabolism?

it causes a greater drop in basal metabolism than in weight

What happened to most contestants from Season 8 of the biggest loser?

13 out of 14 regained weight; some exceeded their starting weight

What persisted long after the competition (biggest loser)?

suppressed metabolic rates

What did the rhesus monkey study show?

Caloric restriction reduced age-related disease and increased longevity

What happened to prisoners asked to overeat in the study about overeating?

Gained weight quickly at first, then struggles to gain more. Most returned to normal weight after

What is homeostasis?

The body’s effort to maintain internal stability

What is a “set point”?

The body’s regulated target weight range

What does the ventromedial hypothalamus (VMH) do?

Acts as the satiety center

What happens if the ventromedial hypothalamus is damaged?

Leads to overeating

What does the lateral hypothalamus (LH) do?

stimulates hunger

What happens if the lateral hypothalamus is damaged?

leads to not eating (aphagia)

What is ghrelin?

A stomach hormone that stimulates hunger

What is PYY 3-36 and what does it do?

Released by the colon to reduce appetite.

What is GLP-1?

A gut hormone that suppresses hunger and slows digestion.

What role does insulin play in hunger?

High or low levels can both stimulate eating.

What is leptin?

A protein hormone from fat cells that signals fat stores to the brain.

What happens in ob/ob mice?

They lack leptin, overeat, and become obese.

What does injecting leptin into ob/ob mice do?

Causes them to lose weight.

Do obese humans usually lack leptin?

No; they usually have more leptin, but may be resistant to it.

What does the arcuate nucleus detect?

Hormones like leptin, ghrelin, insulin, PYY, and GLP-1.

What do POMC neurons do?

Signal satiety via α-MSH

What do NPY neurons do?

Stimulate hunger and block satiety signals.

What is a sleeve gastrectomy?

Stomach is reduced to limit food intake and ghrelin secretion

What is gastric bypass?

Bypasses part of the small intestine to reduce calorie absorption.

What is a gut liner?

A tube inserted into the intestine to block nutrient absorption.

Which fat distribution is riskier: belly or thigh fat?

Belly fat—linked to metabolic syndrome.

What are some diseases linked to obesity?

Cardiovascular disease, Type 2 diabetes, high blood pressure, osteoarthritis.

What BMI level has the highest mortality risk?

Morbid obesity (BMI > 40).

What is anorexia nervosa?

Intentional starvation for weight loss, despite being underweight.

What are some symptoms of anorexia?

No menstruation, brain atrophy, brittle bones, obsession with food.

How deadly is anorexia?

Highest mortality rate among eating disorders (3%).

What is bulimia nervosa?

Cycles of binge eating and purging.

What are some consequences?

Tooth decay, esophageal damage, anemia.

How is bulimia different from anorexia?

Individuals may appear to maintain normal weight and are more likely to seek treatment.

What is binge eating disorder?

Eating large quantities uncontrollably without purging.

How often must it occur to qualify as a disorder?

At least once a week for three months.

What treatments are helpful for eating disorders?

SSRIs