M38: hunger motivation

A.L. Washburn

swallowed balloon attached to recording device, discovery confirm stomach contracts whenever we feel hunger

glucose

form of sugar that circulates in blood & is major energy source for body tissues

when glucose level low, stomach intestines & liver tell brain to eat

hypothalamus

some areas stimulate & suppress appetite

performs body maintenance functions: control of hunger, thirst, & body temp

insulin

controls blood glucose levels & converts food into energy; secreted by pancreas

ghrelin

increases appetite by telling brain you’re hungry

secreted by empty stomach

orexin

increases desire for food; works with ghrelin

leptin

decrease appetite & food seeking behavior; secreted when set point is reached, triggered by hypothalamus

PYY

hormone concerned with hunger & lack of hunger

sends “im not hungry” signals to brain; located in digestive tract

set point

weight thermostat

appetite hormones & brain activity work together to keep you at “normal” weight range

when exceed weight, set point signals body to decrease appetite hormones & increase energy expenditure

when fall below weight, set point signals body to restore lost weight by increasing hunger suppressing hormone & decrease energy output

basal metabolic rate (BMR)

measures hm energy is used to maintain basic body functions when body at rest

fluctuates as u age & change lifestyle

tense or depressed,

crave starchy, carbohydrate-laden foods (pasta, chips, sweets boost neurotransmitter serotonin for calming effects)

preferences for sweet & salty tastes are genetic & universal but conditioning can intensify/alter preferences

given highly salty food → like excess salt

neophobia

dislike of unfamiliar things

was adaptive for ancestors to protect

ppl who repeatedly sample novel food come to appreciate new taste

ecology of eating

situations control our eating

eating more with others: presence amplify natural behavior tendencies

unit bias occurs with similar mindlessness: portion size matters

food variety: eat more than we do when foods are abundant & varied

obesity

having excess body fat, results in higher weight

determined using body mass index

increases diabetes, high blood pressure, heart disease, etc

fat

ideal form of stored energy, fuel reserve to carry body through periods of time when food is scarce

metabolism

when fat, require less food to maintain weight than to attain

fat has lower metabolic rate than muscle

overweight person’s drop below set point,

hunger increase & metabolism decreases

body adapts to starvation by burning off fewer calories

people’s weight

resemble their biological parents

identical twins have closely similar weights

genes explain 2/3 of varying body mass

sleep loss

more vulnerable to obesity

with sleep depreviation,

levels of leptin (reports body fat to brain) fall & ghreline rise

social influence

most likely to become obese when a friend became obese

environmental influences weght

changing food consumption & activity levels are working

eating more, moving less