Review from Yesterday: Theories

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Review from Yesterday Theories

• Pattern of Recognition HW

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Humanistic Theory Maslows Hierarchy of Motives

• Motivation is affected by how we perceive the
  world, how we think about ourselves, and the
  degree to which the environment is supportive and
  encouraging
• Abraham Maslow suggested that motives are
  divided into several levels from basic survival
  needs to psychological and self-fulfillment needs

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The Triangle

• Higher-level needs wont become active until
  lower-level needs have been satisfied.
• Self-actualization the full use of personal
  potential.

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Can you think of???

• Can you think of any example from contemporary
  life that would challenge the validity of
  Maslows hierarchy?

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Maslow Activity

• ME 3 Homework
• Think of examples in your life.

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Hunger
Hunger is both physiological and psychological.
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Keys (1950)

• Fed 36 volunteers just enough food to maintain
  their initial weight.
• Then, for 6 months, they cut this food intake in
  half.
• Results volunteers became apathetic, obsessed
  with food, lost interest in sex and social
  activities
• Maslow basic need was not being met.

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Question

• What triggers hunger? Is it the pangs of an
  empty stomach?
• Washburn and Cannon, 1912, tried to find out.

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Physiology of Hunger

• Washburns studies showed hunger was partially
  related to the stomach.
• But those with their stomachs removed still feel
  hunger.

RESULTS HUNGER IS BOTH PSYCHOLOGICAL AND
PHYSIOLOGICAL!!
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The Brain
In the 1960s it was discovered that hunger comes
from..
The Hypothalamus
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Drives as States of the Brain

• The hub of many central drive systems lies in the
  hypothalamus
• i.e. hunger, thirst, sex

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The Hypothalamus Hunger

• Along the sides of the hypothalamus is the
  lateral hypothalamus which brings on hunger.

Stimulate the lateral hypothalamus and even a
well fed animal will begin to eat.
Lesion the lateral hypothalamus and a starving
animal will have no interest in food.
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The Hypothalamus and Hunger

• Along the lower middle section of the
  hypothalamus is the ventromedial hypothalamus
  which depresses hunger.

Stimulate the ventromedial hypothalamus and the
animal will stop eating
Lesion the ventromedial hypothalamus the animal
will continuously want to eat.
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Hypothalamus
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Munchies?

• The paraventricular nucleus of the hypothalamus
  very sensitive to neuropeptide-Y (NPY).
• When NPY is present in large amounts, animals
  will eat until full.
• Hypothalamus responds in much the same way to a
  chemical in marijuana.

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Hormones of the Hunger Drive
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Glucose

• Form of sugar which circulates through the body
• Glucose is converted by the liver and stored as
  glycogen
• One feels hunger when the levels become low.

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Insulin

• Hormone which allows the body to use glucose for
  energy or fat production
• Secreted by the pancreas
• Controls blood levels of glucose and promotes the
  uptake of glucose by the muscles and other body
  tissues
• As insulin levels increase, glucose levels
  decrease HUNGER.

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Body Chemistry

• About 30 minutes before you eat, you experience
• A slight increase in blood levels of insulin and
• A slight decrease in blood levels of glucose.
• Even if you do not eat, glucose will return to
  its baseline level.
• Prior to eating, body temperature increases and
  metabolism decreases.
• As the meal is consumed, this internal
  physiological pattern reverses.

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TO sum it UP

• 1. Insulin is secreted by the pancreas to
  increase the use of glucose in muscles and
  tissues.
• 2. The decrease in glucose caused by an increase
  in insulin results in a feeling a hunger.

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Satiation

• Feeling of fullness and diminished desire to eat
• that accompanies eating a meal
• Hormones cholecystokinin (CCK) and Glucagon-like
  peptide (GLP-1) are secreted by the intestines
  it promotes satiation and reduces or stops eating
  
• 2. Hormone leptin Protein secreted by
  bloated fat cells when abundant, sends a
  message to stop eating to brain that increases
  metabolism and decreases hunger.

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Appetite Hormones

• Insulin Hormone secreted by pancreas controls
  blood glucose.
• Leptin Protein secreted by bloated fat cells
  when abundant, sends a message to stop eating
  to brain that increases metabolism and decreases
  hunger.
• Orexin Hunger - triggering hormone secreted by
  hypothalamus. As glucose levels drop, orexin
  levels increase and person feels hungry
• Ghrelin Hormone secreted by empty stomach sends
  "I'm hungry" signals to the brain.
• Corticotropin-Releasing Hormone (CRH) hormone in
  hypothamalus that sends "I'm not hungry" signals
  to the brain.

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Regulating Appetite Body Weight

• Appetite is stimulated () by increased levels of
  ghrelin, orexin, and neuropeptide Y.
• Appetite is suppressed (-) by increased levels
  of leptin, insulin, CCK, and CRH

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Set Point

• The proportion of body fat that tends to be
  maintained by changes in hunger and eating.
• Hypothalamus acts like a thermostat.
• We are meant to be in a certain weight range.
• When we fall below weight our body will increase
  hunger and decrease energy expenditure (Basic
  Metabolic Rate).
• What happens if we go above our set point?

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Set Point
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Set Point Regulates Body Weight

• During periods of negative energy balance and
  weight loss, decreased leptin and insulin levels
  promote the secretion of neuropeptide Y (NPY) by
  the hypothalamus. NPY triggers eating behavior,
  reduces body metabolism, and promotes fat
  storage.
• When leptin and insulin levels increase,
  corticotropin-releasing hormone (CRH) activity
  increases in the hypothalamus and surrounding
  areas. CRH reduces food intake and increases body
  metabolism.

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Basal Metabolic Rate (BMR)

• The bodys resting rate of energy expenditure
• Want to calculate your own Body Mass Index?

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Energy Balance

• Positive energy balance occurs when caloric
  intake exceeds calories expended for energy. The
  excess glucose is converted to body fat.
• Negative energy balance occurs when caloric
  intake falls short of the calories expended for
  energy. Body fat stores shrink as the reserve
  energy in fat cells is used

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Basal Metabolic Rate

• The rate at which the body uses energy for vital
  functions while at rest
• Factors that influence BMR
• Age
• Sex
• Size
• Genetics
• Food intake

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There is a steep decline in the rate at which
your body uses energy for vital functions, such
as heartbeat, breathing, and body heat. Your BMR
continues to decrease by about 2 to 3 percent
during each decade of adulthood. At all points
in the lifespan, womens metabolic rate is 3 to 5
percent lower than mens
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Psychological Factors of Hunger

• If hunger is controlled by internal factors, why
  is obesity an issue?
• External factors of eating
• Emotions
• Culture
• External cues availability,
• taste preference

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Taste Preferences

• Food taste better and we chew less when we are
  hungry (beginning of a meal).

Food tastes worse and we chew more when we are
not hungry (at the end of the meal).
Its weird, the better the food tastes, the less
time we leave it in our mouths.
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Psychological factors that trigger eating

• Through classical conditioning, the time of day
  at which you normally eat acts as a conditioned
  stimulus and elicits reflexive internal
  physiological changes (the CR), which increases
  your hunger
• Positive reinforcement plays a role in eating
  voluntary eating behaviors are followed by the
  addition of a reinforcing stimulusfood
• Due to prior learning experiences, certain
  tastes, especially sweet, salty, and fatty
  tastes, hold greater positive incentive value

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Variety of Factors Influence Hunger
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Factors Affecting Food Choices

• Binder Packet M4 and M5 Do tonight will not
  be collected, but important to understanding and
  insight.

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The Obesity Epidemic
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Excess Weight and Obesity

• Obesitycondition characterized by excessive body
  fat and a BMI equal to or greater than 30.0
• Overweightcondition characterized by BMI between
  25.0 and 29.9

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Factors Contributing to Being Overweight

• Highly palatable foodwe eat because it tastes so
  good
• SuperSize Itfood portions are larger than
  necessary for health
• Cafeteria Diet Effectmore food and more variety
  leads us to eat more
• Snackingdoes not cause us to eat less at dinner
• BMRchanges through the lifespan
• Sedentary lifestyles

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Factors in Obesity

• Genetic susceptibility some people are more
  likely to be predisposed to obesity
• Leptin resistance condition where
  higher-than-normal levels of leptin do not
  produce desired physiological response
• Weight cycling repeated dieting, weight loss and
  weight gain tends to result in higher weight and
  reduced BMR.

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Were 1!
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Epidemic of Overweight and Obese Americans

• The problem of being overweight escalates during
  young and middle adulthood.
• Males outpace females in being overweight in each
  age group.

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Research on Weight Regulation and Dieting

• No consistent personality trait differences
  found between obese and non-obese people (e.g.,
  willpower, anxiety)
• Dieters and obese are more likely to eat in
  response to stress than non-dieters
• Family environment of little importance in
  determining body weight genetics plays a large
  role
• Number of fat-storage cells is a major
  determinant of body weight

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Research on Weight Regulation and Dieting

• Fat cells are determined by genetics and food
  intake
• They increase with weight gain, but merely shrink
  with weight loss may stimulate hunger
• Weight loss causes a decline in basal metabolism

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Eating Disorders Briefly!!

• Anorexia aversion to food
• Bulimia binge and purge cycle
• Binge Eating Disorder most common!! Fills an
  emotional void.