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Hunger-

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Hunger-

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  1. Hunger- • What are some of the variables that influence when we eat?

  2. 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

  3. 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

  4. 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

  5. Problems with set point theory • how does it explain eating disorders (in either direction) • can’t 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

  6. 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:

  7. CNS regions involved in eating • VMH - ventromedial nucleus of the hypothalamus

  8. CNS regions involved in eating • VMH - ventromedial nucleus of the hypothalamus characteristics associated with VMH lesions overeating or hyperphagia

  9. weighs ~ 300 g weighs ~ 1200 g

  10. CNS regions involved in eating • VMH - ventromedial nucleus of the hypothalamus characteristics associated with VMH lesions hyperphagia - dynamic phase

  11. 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

  12. 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

  13. other interesting characteristics • finicky eaters

  14. CNS regions involved in eating • VMH - ventromedial nucleus of the hypothalamus • important issue – PVN - paraventricular nucleus involvement

  15. 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!)

  16. 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

  17. 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”

  18. hunger and satiety compounds • Serotonin • often problematic; phen/fen combination

  19. Eating Disorders • Obesity – what causes obesity? • eating patterns, genetics, metabolism, etc .

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

  21. 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.

  22. BMI • Body Mass Index = weight (kg) / height squared (m²)

  23. 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 > 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)

  24. Obesity is associated with an increased risk* of:

  25. 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?)

  26. 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

  27. Treatment of obesity • drug treatments early – amphetamine more recent - 5HT drugsSibutramine (Meridia)

  28. Treatment of obesity • drug treatments early – amphetamine more recent - 5HT drugsSibutramine (Meridia) (Reductil in UK) • jaw wiring • surgery – (Bariatric)

  29. Other end of the spectrum • anorexia • occurs ~ 1% females –typically teens to 20’s • bulimia – • harder to estimate – more likely 4% or so affected

  30. 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

  31. The illness typically occurs in teen or early 20’s • 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

  32. 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

  33. 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

  34. 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

  35. 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.

  36. What are the underlying causes?