The Motivation of Hunger Flashcards by Jonah Nieman

Biological Factors in the Regulation of Hunger
Stomach Contractions
Theories of hunger that focus on a host of factors

Stomach Contractions–> often accompany hunger, but do not cause it .

Theories–> Brain Regulation, Glucose and Digestive Regulation, Hormonal Regulation

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Brain Regulation

Research with lab animals eventually suggested that the experience of hunger is controlled in the brain – specifically the HYPOTHALAMUS

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The hypothalamus

Two parts of the hypothalamus that play a large role in the modulation of hunger:

Neural Circuits in the hypothalamus

is a tiny structure involved in the regulation of a variety of biological needs related to survival.

The ARCUATE NUCLEUS (recently seen as more important) and the PARAVENTRICULAR NUCLEUS play large roles in the modulation of hunger.

contemporary theories of hunger focus more on neural circuits that pass through areas of the hypothalamus rather than on anatomical centres in the brain.

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Glucose Regulation

much of the food is produced into glucose –> then circulates into the blood.
low levels of glucose –> hungry
high levels of glucose–> people feel satiated
produced the GLUCOSTATIC THEORY( eventually proved flawed)

it appears that the arcuate nucleus in the hypothalamus is sensitive to glucostatic fluctuations that contribute to the modulation of hunger.

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Glucostatic theory

proposed that fluctuations in blood glucose level are monitored in the brain where they influences the experience of hunger.

this theory gradually ran into complications.

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Digestive Regulation

Walter Cannon (not totally crazy)

the digestive system also includes other mechanisms that influence hunger.

Walter Cannon might not have been completely wrong by saying that the stomach regulates hunger.

after you have consumed food, cells in the stomach can send signals to the brain stem that inhibit further eating.

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Hormonal Regulation

Types of hormones involved in hunger

A variety of hormones circulating the bloodstream also appear to contribute to the regulation of hunger.

Insulin, ghrelin, CCK, leptin
the hormonal signals that influences hunger (above) all seem to converge in the hypothalamus.

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Hormonal Regulation – Insulin

Hormone secreted by the pancreas. It must be present for cells to extract glucose from the blood. The secretion of insulin is associated with increased hunger.
The mere sight and smell of food can stimulate the secretion of insulin. Insulin levels appear to be sensitive to the body’s fat stores.

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Hormonal Regulation – CCK

After food is consumed, the upper intestine releases a hormone called CCK that delivers satiety signals to the brain –> this reduces hunger.

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Hormonal Regulation – Ghrelin

After going without food for a while, the stomach secrets ghrelin. This causes stomach contractions and promotes hunger.

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Hormonal Regulation – leptin

leptin is produced by fat cells throughout the body, higher levels of fat generate higher levels of leptin.

Leptin circulates throughout the bloodstream and ultimately provides the hypothalamus with information about the body’s fat stores. When leptin levels are higher, the propensity to feel hunger reduces

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Environmental Factors in the Regulation of Hunger

three key environmental factors

(1) The availability of food. (2) Learned preferences and habits (3) stress)

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Food availability and Related Cues

Variables that exert significant influence over food:

most research in this area operate by the concept of homeostasis

however some theorists emphasize the incentive value of food and argue that humans and other animals are often motivated to eat not by the to compensate for energy deficits but by the anticipated pleasure of eating.

Variables that exert significant influence over food: Palatability, Quantity available, variety, presence of others

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Variables that exert significant influence over food: Palatability

445

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Variables that exert significant influence over food: Quantity available

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Variables that exert significant influence over food: Vairiety

445

Variables that exert significant influence over food: Presence of others

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Eating and exposure to environmental cues

eating can also be triggered by exposure to environmental cues that have been associated with eating. (television commercials).

Eating and Social Action

The presence of others generally inhibits eating. But, under certain specific conditions, eating may increase. Our eating is influenced by extant social norms determined by the behaviour of the others around us at the time.

Learned Preferences and Habits

People from different cultures display very different patterns of food consumption.

Humans do have some innate taste preferences of a general sort (sweet tastes)

Taste preferences are partly a function of learned associates formed through classical conditioning.

Conditioning also likely plays a role in our game (hot dog at the leafs game) – a food is associated with fun or memorable event).

Observational learning – exposure to certain foods –children often are exposed to foods that the adult has tried first.

Stress and Eating

studies have shown that stress leads to increased eating in a substantial portion of people. Some people believe this is because people believe the enjoyable treat will make them feel better. however there is little evidence supporting this idea.

Eating and Weight: The Roots of Obesity.

Obesity is increasingly recognized as a major health concern. Overweight and obese are based on BODY MASS INDEX. BMI over 30 is considered obese, while BMIs between 25 and 29.9 are considered overweight.

Having obese parents increases the odds of obesity in children.

Obesity is a significant health problem that elevates one’s mortality risk.

Obesity

the condition of being overweight

Body Mass Index (BMI)

which is an individual’s weight (in kilograms) divided by height (in metres) squared.

Overweight people are more vulnerable to:

cardiovascular diseases, diabetes, hypertension, respiratory problems, gallbladder disease, stroke, arthritis, muscle and skeletal pain, and some types of cancer.

Genetic Predispositon

Differences in weight and weight gain have a genetic basis. Discovered through twin and adopted children --> resemble to biological parents weight more.

Excessive Eating and Inadequate Exercise

The bottom line for overweight people is that their energy intake from food consumption chronically exceeds their energy expenditure from physical activities and resting metabolic processes. they eat too much in relation to their level of exercise

Excessive Eating and Inadequate Exercise-- "Toxic Environment"

Modern societies have cerated a "toxic environment" for eating. This increasingly toxic eating environment have been paralleled by declining physical activity

Sensitivity to External Cues -- Stanley Schachter "externality hypothesis"

According to this notion,overweight people respond readily to environmental cues, such as the availability and attractiveness of food, which often trigger unnecessary eating.

Sensitivity to External Cues -- Judith Rodin -- opposed to "externality hypothesis

she questioned key tenets of the theory she noted that the sight, smell, and sound of a grilling steak can elicit insulin secretions (internal signals) that lead to increased hunger. She also mentioned that not all overweight people are hypersensitive to external cues, and that normal weight people are not necessarily insensitive to external food cues.

Sensitivity to External Cues -- Herman and Polivy -- re-evaluate the externality hypothesis

introduced a distinction between NORMATIVE and SENSORY external cues Herman and Polivy argue that it is sensory external cues that obese people are especially sensitive to.

Normative external cues -- Sensitivity to External Cues -- Herman and Polivy

normative cues are indicators of socially appropriate food intake -- what, when, and how much one should eat.

Sensory external cues -- Sensitivity to External Cues -- Herman and Polivy

Sensory cues are characteristics of the food itself, such as palatability, that make people more or less likely to consume it.

The Concept of Set Point -- Richard Keesey

that they body may have a set point, or a natural point of stability in body weight. SET-POINT THEORY proposes that the body monitors fat-cell levels to keep them (and weight) fairly stable. set-point theory asserts than obese person's body will initiate processes that actively defend an excessive weight

Settling-point theory

opposed to the set-point theory SETTLING-POINT THEORY proposes that weight tends to drift around the level at which the constellation of factors that determined food consumption and energy expenditure achieves an equilibrium. according to this view, weight tends to remain stable as long as there are no durable changes in any of the factors that influence it. Settling-point theory suggests that if an obese person makes long-term changes in eating or exercise, that person's settling point will drift down ward without active resistance.

Dietary Restraint

According to this theory, chronic dieters are restrained eaters-- people who consciously work overtime to control their eating impulses and who feel guilty when they fail. To lose weight, restrained eaters go hungry much of the time. However if they slip, they often over eat --> this can lead to overeating and contribute to obesity.

Eating Disorders -- Anorexia nervosa

a disorder in which (mostly) young women literally starve themselves, sometimes to death.

Eating Disorders -- Bulimia Nervosa

in which (mostly) young women alternate between binge eating and purging.