Homeostasis
This involves mechanisms which detect the state of the internal environment. There is a time lag between restoring equilibrium and measuring effect.
For a hunger mechanism to be adaptive, it must anticipate and prevent energy deficits.
Dual-Process Model
Decline in glucose
|
Activates lateral hypothalamus
|
Hunger
|
Search and consume food
|
Glucose rises
|
Activates ventromedial hypothalamus
|
Feeling of satiation
|
Stops further eating
Lateral Hypothalamus
- Functions as the feeding centre, stimulating feeding in response to signals from the body.
- Damage to LH can cause aphagia. Stimulation elicits feeding behaviour.
- The view that LH serves as an 'on switch' for eating has problems - damage to LH had other behaviour deficits (thirst and sex).
Research: Sakuri (1998)
Ventromedial Hypothalamus
- Part of the hypothalamus that functions as a satiety centre to inhibit feeding.
- Damage to the VMH caused rats to overeat - hyperphagia.
- Usually overeating only occurred when there was also damage to the paraventricular nucleus.
Research: Gold (1973)
Neuropeptide Y
- Important in turning on eating. When injected into hypothalamus of rats, it caused them to begin eating despite having eaten before.
- Obese people may have an over-production of NPY.
Research: Marie et al (2005)
Neural Control of Cognitive Factors
- The Amygdala - Thought to be primarily in the selection of foods on the basis of previous experience.
- Rolls and Rolls (1973)
- Inferior Frontal Cortex - Thought to be linked with odours and food response. Diminished odour response decreased eating.
Research: Zald and Pardo (1997)
Showing posts with label Eating Behaviour. Show all posts
Showing posts with label Eating Behaviour. Show all posts
Wednesday, 4 November 2015
Dieting
Restraint Theory
Restraint has become synonymous with dieting. Research suggests 89% of the female population in the UK consciously restrain their food intake at some point in their lives.
Research: Herman and Mack (1975)
Support for the claim that dietary restraint can lead to overeating comes from Wardle and Beales (1988).
Boundary Model
Introduced by Herman and Polivy - explains why restrained eaters eat more after preloads.
The Boundary Model - Hunger keeps intake of food above a certain minimum, and satiety works to keep intake below some maximum level. Between these two levels, psychological factors have the greatest impact on consumption. Dieters tend to have a larger range between hunger and satiety. Restrained eaters have a self-imposed desired intake and once they have gone over this boundary, they continue to eat until they reach satiety. This leads to the 'what-the-hell' effect.
Role of Denial
Attempting to suppress or deny a thought frequently has the opposite effect, e.g. Wegner et al (1987).
As dieters begin to restrain themselves and make certain foods 'forbidden', they begin to think about the foods more.
Motivation
Motivation from the individual and others has shown important in the success/failure of dieting. If someone is motivated, they are usually more successful in their diet.
Research: Thomas and Stern (1995)
Detail
When people get into a routine, food becomes boring and same-ish. To avoid this, people should concentrate on details of their food to be more successful with their dieting.
Research: Jelly Beans Experiment
Social Support
Support groups like WeightWatchers have a huge success rate mainly attributed to their support systems and the support people get from other members.
Research: Lowe et al (2004)
Goal Setting
When people set goals, they generally feel more motivated to continue until they reach the goals they've set.
Research: Bartlett (2003)
Restraint has become synonymous with dieting. Research suggests 89% of the female population in the UK consciously restrain their food intake at some point in their lives.
Research: Herman and Mack (1975)
Support for the claim that dietary restraint can lead to overeating comes from Wardle and Beales (1988).
Boundary Model
Introduced by Herman and Polivy - explains why restrained eaters eat more after preloads.
The Boundary Model - Hunger keeps intake of food above a certain minimum, and satiety works to keep intake below some maximum level. Between these two levels, psychological factors have the greatest impact on consumption. Dieters tend to have a larger range between hunger and satiety. Restrained eaters have a self-imposed desired intake and once they have gone over this boundary, they continue to eat until they reach satiety. This leads to the 'what-the-hell' effect.
Role of Denial
Attempting to suppress or deny a thought frequently has the opposite effect, e.g. Wegner et al (1987).
As dieters begin to restrain themselves and make certain foods 'forbidden', they begin to think about the foods more.
Motivation
Motivation from the individual and others has shown important in the success/failure of dieting. If someone is motivated, they are usually more successful in their diet.
Research: Thomas and Stern (1995)
Detail
When people get into a routine, food becomes boring and same-ish. To avoid this, people should concentrate on details of their food to be more successful with their dieting.
Research: Jelly Beans Experiment
Social Support
Support groups like WeightWatchers have a huge success rate mainly attributed to their support systems and the support people get from other members.
Research: Lowe et al (2004)
Goal Setting
When people set goals, they generally feel more motivated to continue until they reach the goals they've set.
Research: Bartlett (2003)
Monday, 2 November 2015
Attitudes to food
Health
Different dietary conditions impact the types of foods people can consume.
Crohn's -
- Inflammatory bowel syndrome
- 115,000 in the UK
- Avoid gluten, dairy, raw fruit & veg, dairy, fatty and fried foods, alcohol, caffeine
Coeliac-
- 1 in 100 worldwide
- Small intestine
- No gluten because it can't be digested
Diabetes
- 3.3 million diagnosed in the UK
- 590,000 have it and don't know
- Struggle with glucose and try not to consume high sugar foods
- Another factor that influences people's eating behaviour is the desire to eat foods that are regarded as nutritious and to avoid ones that have been labelled unhealthy.
- Education campaigns advise us to eat a diet that is low in fat and salt, high in carbohydrates and includes 5 portions of fruit and veg.
- Convenience and effort
- Availability
- Cost
- Health information & media
Research
- Rapopori (2003)
- Tuorila & Pangborn (1988)
- Steptoe et al (1995)
Learning
Neophobia is a basic survival mechanism which tends to decrease with age. Experience and familiarity increase food preference.
Operant Conditioning
- Direct reinforcement from parents is used, commonly by reward e.g. 'eat your greens and you can have pudding'.
- This doesn't usually work because it increases desire for reward foods and decreases liking of non-preffered foods.
Parental Attitudes and food preference (parental modelling)
- Mother provides food for child, therefore, the mother's attitude will affect the child's preference.
- If the mother is concerned by nutrition, she will work harder to give her child a balanced diet.
- Parents are key role models for children.
- When children reach school, peers become important.
Associative learning: classical conditioning
- There may be aspects of the environment, specific behaviours or even food that impacts on what we eat.
- We can associate foods with physiological consequences like being ill.
Social Learning theory
- Learning through observation and vicarious reinforcement.
- Peers and parents model behaviour.
- Media models behaviour.
Media
- Magazines and TV influence.
- Makes foods look more appealing through advertising.
Research:
- Birch & Malin (1982)
- Meyer and Gast (2008)
Different dietary conditions impact the types of foods people can consume.
Crohn's -
- Inflammatory bowel syndrome
- 115,000 in the UK
- Avoid gluten, dairy, raw fruit & veg, dairy, fatty and fried foods, alcohol, caffeine
Coeliac-
- 1 in 100 worldwide
- Small intestine
- No gluten because it can't be digested
Diabetes
- 3.3 million diagnosed in the UK
- 590,000 have it and don't know
- Struggle with glucose and try not to consume high sugar foods
- Another factor that influences people's eating behaviour is the desire to eat foods that are regarded as nutritious and to avoid ones that have been labelled unhealthy.
- Education campaigns advise us to eat a diet that is low in fat and salt, high in carbohydrates and includes 5 portions of fruit and veg.
- Convenience and effort
- Availability
- Cost
- Health information & media
Research
- Rapopori (2003)
- Tuorila & Pangborn (1988)
- Steptoe et al (1995)
Learning
Neophobia is a basic survival mechanism which tends to decrease with age. Experience and familiarity increase food preference.
Operant Conditioning
- Direct reinforcement from parents is used, commonly by reward e.g. 'eat your greens and you can have pudding'.
- This doesn't usually work because it increases desire for reward foods and decreases liking of non-preffered foods.
Parental Attitudes and food preference (parental modelling)
- Mother provides food for child, therefore, the mother's attitude will affect the child's preference.
- If the mother is concerned by nutrition, she will work harder to give her child a balanced diet.
- Parents are key role models for children.
- When children reach school, peers become important.
Associative learning: classical conditioning
- There may be aspects of the environment, specific behaviours or even food that impacts on what we eat.
- We can associate foods with physiological consequences like being ill.
Social Learning theory
- Learning through observation and vicarious reinforcement.
- Peers and parents model behaviour.
- Media models behaviour.
Media
- Magazines and TV influence.
- Makes foods look more appealing through advertising.
Research:
- Birch & Malin (1982)
- Meyer and Gast (2008)
Sunday, 11 October 2015
Mood and Eating Behaviour
Hunger is associated with increased arousal, vigilance and irritability. Studies have shown that people who are stressed or depressed increase the carbohydrate and fat content of their meals. This is associated with better mood and more energy.
The Serotonin hypothesis: Carbohydrates such as chocolate contain the amino acid tryptophan. This is used by the brain in the manufacture of the neurotransmitter serotonin. Low levels of serotonin are associated with depression and it has been proposed that people with stress or depression take in more carbohydrates because this increases serotonin.
However, the presence of a small amount of protein prevents the tryptophan from entering the brain and so serotonin will not increase. This means the serotonin hypothesis is unlikely to explain the effects of high carbohydrate diets.
The Opiate hypothesis: Examples are enkephalin and beta-endorphin. They are released from neurons and act at synapses with opiate receptors. Opiates are similar to the opiate drug heroin. This is highly addictive which can also produce pleasurable feelings, therefore it seems likely that the brain's opiate pathways are part of our reward system, a network of pathways that control out feelings of pleasure and reward. Opiate drugs increase food intake and the perceived tastiness of food.
Binge Eating
- Research has shown that individuals with bulimia nervosa complain of anxiety prior to binge.
- Studies show that before a binge, bulimic individuals have more negative mood states than one hour before a normal snack or meal.
- In studies, binge days were associated with low moods.
- Low moods may make binge-eating more likely.
- Many people tend to comfort eat - supported by Garg et al (2007)
Reinforcement
- Although binge-eating can offer gratification, reinforcement is feeling and studies report a drop in mood immediately after the binge.
- Chocolate has been seen as the ultimate comfort food. Attitudes towards chocolate are influenced by claims that it can lift our mood - supported by Parker et al (2006)
Binge-Eating Disorder - Supported by Wolff et al (2000)
The Serotonin hypothesis: Carbohydrates such as chocolate contain the amino acid tryptophan. This is used by the brain in the manufacture of the neurotransmitter serotonin. Low levels of serotonin are associated with depression and it has been proposed that people with stress or depression take in more carbohydrates because this increases serotonin.
However, the presence of a small amount of protein prevents the tryptophan from entering the brain and so serotonin will not increase. This means the serotonin hypothesis is unlikely to explain the effects of high carbohydrate diets.
The Opiate hypothesis: Examples are enkephalin and beta-endorphin. They are released from neurons and act at synapses with opiate receptors. Opiates are similar to the opiate drug heroin. This is highly addictive which can also produce pleasurable feelings, therefore it seems likely that the brain's opiate pathways are part of our reward system, a network of pathways that control out feelings of pleasure and reward. Opiate drugs increase food intake and the perceived tastiness of food.
Binge Eating
- Research has shown that individuals with bulimia nervosa complain of anxiety prior to binge.
- Studies show that before a binge, bulimic individuals have more negative mood states than one hour before a normal snack or meal.
- In studies, binge days were associated with low moods.
- Low moods may make binge-eating more likely.
- Many people tend to comfort eat - supported by Garg et al (2007)
Reinforcement
- Although binge-eating can offer gratification, reinforcement is feeling and studies report a drop in mood immediately after the binge.
- Chocolate has been seen as the ultimate comfort food. Attitudes towards chocolate are influenced by claims that it can lift our mood - supported by Parker et al (2006)
Binge-Eating Disorder - Supported by Wolff et al (2000)
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