chapter 10 hunger

8/3/2019 Chapter 10 Hunger

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Chapter 10 Hunger

1. Hungera. When do we eat?

i. When were hungry!b. When are we hungry?

i.

When there is no food in our stomach.c. How do we know when our stomach is empty?i. Our stomach growls. These are also called hunger pangs.

2. The physiology of Hungera. What physiological factors produce hunger?

i. It starts at Ancel Keys (scientists) et.al (1950) semi starved men by reducing bodyweight to 25% below starting weight.

1. Keys said we need to sell the experiment to the volunteers! We are askingthem to starve themselves. These men want to sacrifice themselves. They

want to prove that they can be heroes too just without going to war! They

were digging ditches and other meaningless tasks because the governmentdoesnt know what else to do with them. He came up with the idea of making

a brochure and on the cover we show a picture of starving children in

occupied France. We write will you starve that theyll be better fed.a. They were examined and weighted every day. Scientists were studying

the physical and psychological effects of prolonged famine like semistarvation on healthy men and their subsequent rehabilitation from that

starvation.

b. The first 12 wks will be a standardization period. Each received acontrolled diet of approximate 3200 calories. They were tested theirphysical and mental health.

c. The next 24 wks was the hard part. Their diet will be cut to 1500calories per day, and meals will consist of potatoes, ruda-vegas,

turnips, bread and macaroni! No meat!!! This will mirror the diet inoccupied countries in Europe. This will produce a 25% total weight

loss in a 24 wk period.

d. They were administered a series of metabolic and physicalmeasurement, x-ray examinations, treadmill performance, intelligence

and psychological evaluations.

e. After that they were divided into 4 groups. Each group will receive adifferent rehabilitation diet. The scientists examined how each

rehabilitation diet measures against the others.

f. And after that there will be an unrestricted rehabilitation period.2. Men became preoccupied with food.3. Become preoccupied with the unfulfilled basic need hunger4. Consistent to Maslows idea of a needs hierarchy, the men became food-

obsessed. Talked, daydreamed, collected recipes, read cookbooks, and feastedtheir eyes on delectable forbidden foods.


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ii. Many theories of hunger are historically discussed from the biological component.1. What is it that causes hunger? Is it the pangs of an empty stomach?2. Cannon & Washburn (Psychologist) (1912)

a. Came up with the stomach contraction theory which states that weknow we are hungry when our stomach contracts.

b.

In the notorious balloon study, Washburn trained himself to swallow aballoon which was attached to a tube, then the balloon was inflated

inside of his stomach. When the balloon was inflated, he did not feel

hungry. Later this theory was opposed by the fact that people whosestomach was removed still felt hungry.

c. Hunger pangs: physiological indicator of hungeriii. Tsang (1938) removed rat stomachs, connected the esophagus to the small intestines,

and the rats still felt hungry (and ate food).

1. Some hunger persists similarly in humans whose ulcerated or cancerousstomachs have been removed.

a.

So if the pangs in an empty stomach are not the only trigger of hunger,what else matters?

b. Body ChemistryThe Endocrine System

The HypothalamusThe part of the brain involved with drives associated with survival such as hunger,

thirst, emotion, sex, and reproduction

The Brain

The Hypothalamusthis helps control eating

The Lateral Hypothalamus

(brings on hunger)When deprived of food and blood sugar becomes low, the Lateral Hypothalamus

churns out orexin, a hunger-triggering hormone.

The Ventromedial Hypothalamus

(depresses hunger)Stimulate this area and an animal will stop eating.

Destroyit & the animals intestines will process food very rapidly causing it to eat

more often.

- Manipulating the lateral and ventromedial hypothalamus alters the bodys

weight thermostat, which predisposes us to keep our body at a particular

weight level called set point.

c. The complex interaction of appetite hormones and brain activity may help explain the bodysapparent predisposition to maintain itself at a particular stable weight of set point.

i. When semi-starved rats fall below their normal weight this weight thermostatsignals the body to restore the lost weight: HUNGER INCREASES AND ENERGY

EXPEDITURE DECREASES. IFBODY WEIGHT RISESS AS HAPPENS WHEN

RATS ARE FORCE FEDHUNGER DECREASES AND ENERGYEXPENDITURE INCREASES.

1. Predisposition to maintain weight hunger increases and energy expendituredecreases


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2. If weight is lost, food intake increases and energy expenditure decreases. Ifweight is gained, the opposite takes place.

d. Set Point: a biologically fixed tendency to maintain an optimum weighti. influenced by our heredity and body type

a.

States that we are born with a specific weight that our body is going tobe comfortable at. Any time we try and diet we pull away from that set

point.

e. Research supports instead a settling pointi. Indicates an environmentally and biologically influenced level at which weight settles

in response to caloric input and expenditure1. Noting that food intake and energy output are influenced by environment as

well as biology, some researchers have abandoned the idea of a biologically

fixed set point.

2. They point out that slow, sustained changes in body weight can alter set point,and that psychological factors also sometimes drive feelings of hunger.3. Given unlimited access to a wide variety of tasty foods, ppl and other animalstend to overeat and gain weight.

4. For all these reasons, some psychologist use the term settling point to indicatethe level at which a persons weight settles in response to caloric intake and

expenditure.

f. In order to regulate weight:i. Food intake

ii. Energy outputiii. Basal metabolic rate: the bodys (base) resting rate of energy expenditure

1. In other words, it is the rate at which your body consumes calories when

at rest

3. The Psychology of Hungera. What psychological and cultural factors influence hunger?

i. Memory plays an important role in hunger.1. Rozin and his colleagues tested 2 patients that had no memory for events

occurring more than a minute ago. If, 20 minutes after eating a normal lunch,the patients were offered another, both readily consumed it and usually athird meal offered 20 minutes after the second was finished.

2. This suggests that part of knowing when to eat is out memory of our last meal.As time passes we anticipate eating again and start feeling hungry.

3. Anticipate eating begin to feel hungry

b. Taste PreferenceBody Chemistry and environmental factors together influence not onlywhen we feel hungry, but also what we hunger for- out taste preference.

i. If we feel:1. Tensed or depressed crave carbohydrates (boost)2. Monitored by serotonin levels that produce calming effect3. When stressed even rats find it extra rewarding to scarf down Oreos.


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c. Conditioned tastes: repeated exposurei. Our preferences for sweet and salty tastes are genetic and universal.

ii. Other taste preferences are conditioned, as when ppl are given highly salted foodsdevelop a liking for salt.

iii. Or when ppl who have been sickened develop an aversion to it.1. These types of aversions are called Learned aversions: food that makes you ill

a. Have survival valued. CultureCulture affects tastes too.

i. We tend to avoid unfamiliar foods (e.g., rat, dog, or horse meat) (CHIVO)1. Some cultures enjoy eating the eye of the camel; most North Americans

would find it repulsive.

a. That neophobia the (dislike of things unfamiliar) surely was adaptivefrom our ancestors, wanting to protecting them from potentially toxic

substances.

ii. Other taste preferences are also adaptive.1. We learn to enjoy foods prescribed by our culture (e.g., spicy food)

i. Countries with hot climates use more bacteria-inhibiting spicesin meat dishes.

iii. Appreciation for new tastes increases with frequent exposure to novel (new) foods1. In experiments ppl who repeatedly sample an initially novel fruit drink or

ethnic food typically experience increasing appreciation for the new taste.

2. Exposure to one set of novel foods increases a persons willingness to tryanother.

4. Obesity & Weight Controli. Obesity: A disorder characterized by being excessively overweight.

ii. What factors predispose some people to become and remain obese?1. Lack of exercise and excessive intake of high-calorie food2. Increases the risk for health issues

a. Cardiovascular diseases, diabetes, hypertension, arthritis, and backproblems.

b. Shortens life expectancyc. Research also links womens obesity to their risk of late life

Alzheimers disease and brain tissue loss.

b. The social Effects if ObesityObesity can also be socially toxic, by affecting both how youare treated and how you feel about yourself.

1. Obese ppl know the stereotype; slow lazy, and sloppy.2. Regina Pingtore and her colleagues demonstrated weight discrimination in a

clever experiment. They filmed mock job interviews in which professional

actors appeared either normal weight or as overweight applicants (wearingmake-up and prostheses to make them look 30 lbs heavier). When appearing

overweight, the SAME personusing the same lines, intonations, and

gestures-was rated less worthy of hiring.


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3. Mostly bias in women.4. Other studies reveal that weight discrimination though hardly discussed is

greater than race and gender discrimination.

c. The physiology of Obesityi.

Research on the physiology of obesity challenges the stereotype of severelyoverweight ppl being weak-willed gluttons.

1. 1stconsider the arithmetic of weight gain:a. Ppl get fat by consuming more calories than they expend.b. The energy equivalent to a pound of fat is 3500 calories; therefore

dieters have been told they will lose a lbs. for every 3500caloric

reduction in their diet.

c. SURPRISE: This conclusion is false.2. Environmental influences on ObesityGenes tell an important part of the

obesity story. But research reveals that environmental factors are mighty

important too:a. Social influencePPl are more likely to become obese when a friendbecame obese.

b. If that friend was a close mutual friend the odds almost tripled.c. Sleep Loss- children & adults who skimp on sleep are more vulnerable

to obesity.d. With sleep deprivation, the levels of leptin (which reports body fat to

the brain) fall and ghrelin (the stomach hormone that stimulates

appetite) rise.

3. Fat Cells - Most people think of fat as a still blob, but fat cells releasepowerful chemicals. In obese people, the fat tissue often produces too many

bad hormones and too few good ones

Q: Do people have different numbers of fat cells?o A: A person at a healthy weight might have 10 billion to 20

billion, and an obese person can have up to 100 billion. Babies areborn with about 10 billion. You naturally increase the number of

fat cells, like other kinds of cells, as you grow.

ii. Set Point and Metabolism1. Once we become fat, we require less food to maintain our weight than we did

to attain it.

a. Because compared with other tissues, fat has a lower metabolic rate it takes less food energy to maintain.

2. In a classic month long experiment, obese patients whose daily food intakewas reduced from 3500 to 450 calories lost only 6% of their weight-partly

because their bodies reacted as though they were being starved and theirmetabolic rates dropped about 15%.

3. THIS IS WHY REDUCING YOUR FOOD INTAKE BY 3500CALORIES MAY NOT REDUCE YOUR WEIGHT BY 1 LBS.


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d. Genetic InfluencesSpecifics of our genes predispose the size of our jeans.i. Given an obese parent, a boy is 3 times, and a girl 6 times, more likely to be obese

than their counterparts with normal weight parents.

e. Losing Weighti.

Those who manage to keep pounds off set a realistic and moderate goals,ii. undertaking programs that modify their life-style and ongoing eating behavior.iii. They lose weight graduallyiv. A reasonable time line for a 10% reduction in body weight is 6 months.v. Exercise regularly

f. Eating DisordersVideo:http://youtu.be/RdGFv4BduKw
http://youtu.be/RdGFv4BduKwhttp://youtu.be/RdGFv4BduKwhttp://youtu.be/RdGFv4BduKwhttp://youtu.be/RdGFv4BduKw

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