Obesity: Eating behaviour

Question 1

Obesity

Answer 1

Having too much body fat (BMI over 30)

Question 2

2 biological explanations of Obesity

Answer 2

Genetic

Neural

Question 3

Genetic explanation of Obesity

Answer 3

-Nature, passed down
-Parents, predispose
-DNA produces instructions

Studied 2 ways. Twin studies =
-Studied via concordance rates . Nan et al. Meta analysis of 12 twin studies. found concordance rate of 60 - 80% for MZ twins in BMI

Polygenic determination:
-Polygenic. Locke et al (2015). studies genomes of more than 300,000 people. found 97 different genes associated with BMI

Question 4

Neural expls of Obesity

summary

Answer 4

Focus on two neurotransmitters.
-Serotonin and Dopamine

Serotonin signals to hypothalamus that we have eaten to satiety. Obese people have lower levels of serotonin

Dopamine stimulates areas in the brain that provide feelings of pleasure when we eat. Obese people have less dopamine D2 receptors. Eat more to gain same amount of pleasure

Question 5

Role of serotonin in obesity

Answer 5

involved in regulating human eating behaviour:
-serotonin inhibits parts of the hypothalamus including the ventro-medial hypothalamus.
-Serotonin signals the hypothalamus that we have eaten to satiety. .
-it’s thought that Obese people have less serotonin
-so are less likely to feel satiated
-Thought to link in with depression, a mental illness that causes extremely low levels of serotonin

Question 6

Role of Dopamine in obesity

Answer 6

-has crucial role in brains reward system
-Stimulates areas of the brain that provide feelings of pleasure
Including the hypothalamus and amygdala.
-Dopamine does this in response to behaviours such as eating , which reinforces these behaviours
-Research has found that obese people have significantly less Dopamine D2 receptors than normal- weight controls.
-Low levels of receptors = less sensitive to dopamine
-would not get same same pleasure reward function from eating
-Overeating is an attempt to activate reward centres to gain feeling of pleasure

explaining why obese people overeat addictively

Question 7

3 psychological expls for obesity

Answer 7

-Restraint theory

-Disinhibition

-The boundary model

Question 8

Restraint theory summary

Answer 8

-Cognitive theory
-Obesity caused by restricted eating
-= Setting strict limits (imposing cognitive control)
-Counter productive and self-defeating
-Become pre-occupied with food
-Ignore physiology
-End up eating more/overeating

Question 9

Disinhibition theory

Answer 9

-Obesity is not caused by restrained eating alone
-A period of restraint is often followed by disinhibited eating (eat whatever you want)
-Restrained eaters are vulnerable to cues
-Internal cues (mood) and External cues (media, smells)
-Cues = Disinhibitors
-Leads to a loss of control
-Therefore we binge
-Cognitive process = all or nothing

Question 10

Boundary model summary

Answer 10

-Proposed by Herman and Polivy
-Food intake exists on a continuum from hunger to satiety With a Zone of biological indifference in-between
-Biological processes affect how much we eat at each end of the continuum
-Restrained eaters place cognitive boundaries on self e.g: only eat 1500 calories
- Have larger range between hunger and satiety
-Feel hunger for longer and it takes more food to satisfy them
-when they break the restraint it acts as a disinhibitor
-Experience the ‘what the hell’ phenomena and then eat way beyond a normal eaters satiety boundary

Question 11

How did Ogden research the boundary model

what did he find

Answer 11

(2003) Tested in a laboratory.
-Gave dieters and non-dieters a tate test.
-P.p given either a high calorie ‘pre load’ snack or a low calorie snack.
-After eating, p.p told they were taking part in a taste preference test.
-p.ps lefts alone to eat
-How much they ate was recorded

Found:
-Non-dieters reduced food intake after high calorie
-Dieters increased food intake after high calorie
-Dieters ate less after low calorie