The Motivation of Hunger

1. The Motivation of Hunger Hunger is both physiological and psychological

2. Hunger • When your stomach feels stuffed you probably do not feel hungry and when your stomach is empty you probably get that take me to McD’s feeling. • Researchers used to believe that the feeling of hunger comes from our stomach • To test the theory out, they made some poor soul swallow a balloon and inflated the balloon inside of his stomach

3. Physiology of Hunger • He felt full for awhile but eventually felt hungry again. • The experiment showed hunger was partially related to the stomach. • Additionally, those with their stomachs removed still feel hunger. • So hunger must be also related to the brain

4. The Brain In the 1960’s it was discovered that hunger comes from……….. The Hypothalamus Guides – eating, drinking, and body temperature

5. The Hypothalamus & Hunger • Along the sides of the hypothalamus is the lateral hypothalamus: • It’s the “turning on” eating part of your brain Stimulate the lateral hypothalamus and even a well fed animal will begin to eat. Lesion the lateral hypothalamus and even a starving animal will have no interest in food.

6. The Hypothalamus and Hunger • Along the lower middle section of the hypothalamus is the ventromedial hypothalamus: • “turning off” eating – off switch • which depresses hunger –if stimulated you would feel full. Stimulate the ventromedial hypothalamus and the animal will stop eating Lesion the ventromedial hypothalamus the animal will continuously want to eat.

7. How does the hypothalamus work? • Hypothalamus acts like a thermostat. • We are meant to be in a certain weight range for our body or body type • Set Point Theory • When we fall below ideal weight (or our set point) our body will increase hunger and decreaseenergy expenditure • Basic Metabolic Rate (BMR) – the rate your body burns calories while at rest • What happens if we go above our set point? • The hypothalamus tells us to stop eating and raises our metabolic rate to burn any excess food

8. Physiology of Hunger…Cont. • Glucose • form of sugar that runs through your body – run low on glucose and you will feel hungry • Insulin • hormone that allows our cells to use glucose for energy or convert it to fat • when insulin levels go up, glucose levels go down • Leptin • protein that is produced by bloated fat cells which send out a “stop eating” message • artificially introduced into obese mice caused reduced eating and weight lose

9. Environment and Hunger Externals vs. Internals • Externals: • people whose eating and hunger is triggered more by the presence of food (sight, sound, and smell) than internal factors. • Internals: • people whose eating and hunger is triggered by internal cues, empty stomach, feelings of hunger

10. Taste Preferences – can be based on many things…culture, parents, availability, etc.. Food tastes 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.

11. Culture and Taste

12. Eating Disorders

13. Anorexia Nervosa • An eating disorder in which a normal weight person diets and becomes significantly underweight, yet, still feeling fat, continues to starve.

14. Bulimia Nervosa • An eating disorder characterized by episodes of overeating, usually of high caloric foods, followed by vomiting, laxative use, fasting, or excessive exercise.

15. Obesity Severely overweight • Often over 100 pounds above normal weight • Threatens their health • Typically have unhealthy eating habits or may also be genetically predisposed to obesity

16. Are these disorders cultural?

17. Body Image