Unit 10: Motivation & Emotion
Hunger & Motivation
- Biological Factors in Regulation of Hunger
- Environmental Factors in the regulation of hunger
- Eating & Weight
- Eating Disorders
Biological Factors in Regulation of Hunger
- Hypothalamus – regulation of bodily needs – causes hunger
- Lateral hypothalamus (LH), ventromedial nucleus of the hypothalamus (VMH) – thought to be on and off switches for hunger, not known to be just a part of a larger system
- Arcuate nucleus, Paraventricular nucleus – areas of hypothalamus that are sensitive to hunger and satiety signals
- Neural circuits v. anatomical circuits – no ONE part is responsible for hunger, rather it is an assembly of larger parts that causes hunger
Glucose and digestive regulation
- Glucose – simple sugar, circulates in blood to provide energy
- Glucostatic theory – fluctuations in blood glucose level are monitored in the brain where they influence the experience of hunger – not a fool-proof theory, but ARCUATE NUCLEUS does seem to be sensitive to glucose levels
- Stomach – cells in stomach send messages about stretching to indicate satiety - vagus nerve
- Insulin – hormone that allows cells to extract glucose from the blood – DIABETES is an in adequate supply
- Ghrelin – causes stomach contractions, promotes hunger
- CCK – released by upper intestines after eating to indicate hunger
- Leptin – longer term regulation of hunger, produced by fat cells, gives hypothalamus information about how much fat there is. More fat=more leptin=reduction in hunger
Environmental Factors in the Regulation of Hunger
Availability of food, how delicious food is, learned preferences and habits
Food cues – Do we eat because we are hungry or because food is delicious?
1. Palatability – better taste=eating more
2. Quantity – more there is=more we eat; UNIT BIAS THEORY says that we want to eat the whole of ONE thing (6 inch sub vs. 12 inch)
3. Variety – more types of food=more we eat (sensory-specific satiety is when we eat less if there are few types of food)
4.Presence of others – more people = more eating. EXCEPT for women – women eat more with other women, less with other men
5. Exposure to advertising – more food ads=more eating, and not just the food in the commercial
Habits – preferences are partially genetic (sweet, fatty), part classically conditioned (getting icecream as a treat w/a parent); part exposure (providing a variety of food prevents ‘picky’ eaters)
Eating & Weight
Obes0ity – condition of being overweight
- Sometimes measured by BMI (weight in kilograms divided by height in meters squared [kg/m2]) --> FAIRLY CONTROVERSIAL, EVEN THOUGH IT IS COMMONLY USED.
- BMI does not take into account density of bones, muscle, or fat, just overall weight. So you could be densely muscled but still considered “overweight.”
- It also does not account for builds.
- It also does not differentiate between abdominal fat (dangerous and linked to disease) and fat carried in butt or thighs (largely inert and not linked to disease).
- Does not differentiate between men and women, or across races (bone density)
- BMI Categories:
Underweight = <18.5
Normal weight = 18.5–24.9
Overweight = 25–29.9
Obesity = BMI of 30 or greate
WHY DO WE EAT?
External cues – some research by Schachter suggested that overweight people are more sensitive to external cues (ads, appearance of food, others eating) and healthy-weight people are more sensitive to internal cues (discussed above)
- Problem with this external cue theory is that sights and sounds of food cue insulin secretion, so the line between external and internal cues is blurred
Normative v. Sensory cues – Normative cues are indicators of socially appropriate food intake, sensory cues are characteristics of the food -->Herman and Polivy argue that obese people are especially sensitive to SENSORY CUES
Set Point – your body might have a natural balance of weight. Supported by the fact that weight loss/gains can be hard to keep
20 million women and 10 million men suffer from a clinically significant eating disorder at some time in their life, and eating disorders have the highest mortality rate of any mental illness.
Anorexia Nervosa - eating disorder characterized by an abnormally low body weight, intense fear of gaining weight and a distorted perception of body weight. Anorexia isn't really about food. It's an unhealthy way to try to cope with emotional problems. When you have anorexia, you often equate thinness with self-worth.
- Biological Symptoms - Extreme weight loss, Thin appearance, Abnormal blood counts, Fatigue, Insomnia, Dizziness or fainting, Bluish discoloration of the fingers, Hair that thins, breaks or falls out, Soft, downy hair covering the body, Absence of menstruation, Constipation, Dry or yellowish skin, Intolerance of cold, Irregular heart rhythms, Low blood pressure, Dehydration, Osteoporosis, Swelling of arms or legs
- Psychological/Social Symptoms - Severely restricting food intake through dieting or fasting and may include excessive exercise, bingeing and self-induced vomiting to get rid of the food and may include use of laxatives, enemas, diet aids or herbal products
Bulimia – binging and purging instead of not eating
Pica - compulsive eating of material that may or may not be foodstuff. The material is often consumed in large quantities without regard for nutritional consequencesOrthorexia? Not recognized by DSM-5, this is similar to anorexia but instead of focusing on the amount of food being eaten, it is a focus on ‘purity’ or ‘rightness’ of food being eaten.