Hunger-

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Hunger-

• What are some of the variables that influence
  when we eat?

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Theories to explain eating (and hunger)

• Role of depletion of nutrients
• "Set point theories"- some optimal energy level
  needed and this plays a role in when we stop
  eating

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Theories to explain eating (and hunger)

• Role of depletion of nutrients
• "Set point theories" - all have negative
  feedback systems
• - negative feedback - changes in one direction
  causes a compensatory response in the opposite
  direction possibly a way to maintain
  homeostasis

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Theories to explain eating (and hunger)

• Role of depletion of nutrients
• "Set point theories" - negative feedback loop
• - Lipostatic- we become sated based on our set
  point for body fat
• - Glucostatic- we become sated based on blood
  glucose levels

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Problems with set point theory

• how does it explain eating disorders (in either
  direction)
• cant be explained via an evolutionary
  perspective
• major predictions based on set point have not
  been confirmed
• fail to recognize importance of other factors
  environmental particularly

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Positive incentive theory -

• we are drawn to eat based on anticipated pleasure
  (incentive value)
• factors that influence the pleasurable or
  rewarding aspects of eating include

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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus

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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus
• characteristics associated with VMH lesions
• overeating or hyperphagia

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weighs 300 g
weighs 1200 g
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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus
• characteristics associated with VMH lesions
• hyperphagia - dynamic phase

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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus
• characteristics associated with VMH lesions
• hyperphagia - dynamic phase
• static phase - maintains the higher weight

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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus
• characteristics associated with VMH lesions
• hyperphagia
• dynamic phase
• static phase
• other interesting characteristics- VMH lesions
• increases in blood insulin levels (increases
  production of body fat)
• decrease breakdown of body fat

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• other interesting characteristics
• finicky eaters

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CNS regions involved in eating

• VMH - ventromedial nucleus of the hypothalamus
• important issue PVN - paraventricular nucleus
  involvement

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CNS regions involved in eating

• to reach the VMH you need to go through PVN
  and it may be damage to this region that is
  important (either as well or alternatively!)

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CNS regions involved in eating

• LH lesions
• characterized by no eating or drinking
• - if not force fed, animals will starve to
  death
• - motor disturbances and possibly sensory

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hunger and satiety compounds

• CCK first found in gut somehow provides brain
  about amount of food present
• subsequently a dozen or so found in gut that
  appear to reduce food consumption
• also a limited number of hunger peptides

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hunger and satiety compounds

• Serotonin
• often problematic phen/fen combination

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Eating Disorders

• Obesity what causes obesity?
• eating patterns, genetics, metabolism, etc .

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• Q How many adults are overweight?
• A Nearly two-thirds of U.S. adults are
  overweight or obese

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• Q How has the prevalence of overweight and
  obesity in adults changed over the years?
• A The prevalence has steadily increased over the
  years among both genders, all ages, all
  racial/ethnic groups, all educational levels, and
  all smoking levels.

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BMI

• Body Mass Index weight (kg) / height squared
  (m²)
•  
•  

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• How is overweight and obesity defined?
• OBI over 25 overweight
• OBI over 30 obese
• So how many adults are obese?
• Nearly one-third of U.S. adults are obese (BMI gt
  30).
• All adults (20 years old) 61.3 million (30.5
  percent)Women (20 years old) 34.7 million
  (33.4 percent)Men (20 years old) 26.6 million
  (27.5 percent)

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Obesity is associated with an increased risk of
premature death type 2 diabetes heart disease stroke hypertension gallbladder disease osteoarthritis (degeneration of cartilage and bone in joints) sleep apnea asthma cancer (endometrial, colon, kidney, gallbladder, and postmenopausal breast cancer) high blood cholesterol complications of pregnancy menstrual irregularities hirsutism (presence of excess body and facial hair) stress incontinence (urine leakage caused by weak pelvic-floor muscles) increased surgical risk psychological disorders such as depression psychological difficulties due to social stigmatization
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Eating Disorders

• Obesity what causes obesity?
• evolutionary pressures
• cultural pressures-
• genetic factors
• ob/ob mice
• eat more, use fat calories more efficiently
• discovered the protein leptin (normal for
  satiety?)

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Prader Willi syndrome-

• Deletion of critical region of parental 15th
  chromosome
• 70 of cases
• Mild to moderate mental retardation
• Obsessive compulsive tendencies
• Behavioral outbursts
• Unstable moods
• Low activity levels

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Treatment of obesity

• drug treatments
• early amphetamine
• more recent - 5HT drugsSibutramine (Meridia)
  

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Treatment of obesity

• drug treatments
• early amphetamine
• more recent - 5HT drugsSibutramine (Meridia)
  (Reductil in UK)
• jaw wiring
• surgery (Bariatric)

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Other end of the spectrum

• anorexia
• occurs 1 females typically teens to 20s
• bulimia
• harder to estimate more likely 4 or so
  affected

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Criterion for Anorexia

• Weight 15 below ideal body weight. Refusal to
  maintain a normal weight or above normal weight
  for height and age.
• Intense fear of gaining weight or becoming fat,
  even though underweight.
• Body Image Problems
• 4. No Periods for at least 3 months

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• The illness typically occurs in teen or early
  20s
• 86 report onset of illness by the age of 20
• 10 report onset at 10 years or younger
• 33 report onset between ages of 11-15
• 43 report onset between ages of 16-20

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• This is an illness that persists for many people.
• Only 50 report being cured
• 77 report duration from one to fifteen years
• 30 report duration from one to five years
• 31 report duration from six to ten years
• 16 report duration from eleven to fifteen years

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• This is an illness that persists for many people.
• Only 50 report being cured
• 77 report duration from one to fifteen years
• 30 report duration from one to five years
• 31 report duration from six to ten years
• 16 report duration from eleven to fifteen years
• It is estimated that six percent of serious cases
  die

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Bulemia

• Binge Eating
• -a few to several thousand calories within a few
  hours
• - a feeling that one cannot stop eating although
  one desires to
• 2. Purging
• -vomiting, laxatives, diuretics or excessive
  exercise
• 3. Binging and Purging occurs more than 2 x a
  week for at least 3 months
• 4.Body Image Self evaluation and self esteem is
  overly influenced by weight and shape

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There are many diseases, disorders, and problem
conditions involving food, eating, and weight.

• Dieting teens
• More than ½ teenaged girls are, or think they
  should be, on diets. About 3 become anorexic or
  bulimic.

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What are the underlying causes?