Topics in Psychology

EATING BEHAVIOUR

UNIT 3

SPECIFICATION REQUIREMENTS:TOPIC SPECIFICATION REQUIREMENTS EXAM RELATED Q

EATING BEHAVIOUR • Factors influencing attitude to food and eating behaviour e.g. cultural influences, mood, health concerns•Explanations for success or failure of dieting

•Describe people’s attitudes to food and eating behaviour and discuss at least two factors that affect people’s attitudes to food and eating behaviour.•Describe and evaluate research that has investigated how these factors influence attitudes to food and eating behaviour•D & E key reasons for why dieting succeeds and why it fails.- research

BIOLOGICAL EXPLANATIONS OF EATING BEHAVIOUR

• The role of neural mechanisms involved in controlling eating and satiation•Evolutionary explanations of food preferences

• explain ways in which neural mechanisms control eating behaviour and satiation and evaluate biological explanations of eating behaviours and satiation•Explain and evaluate food preferences from an evolutionary perspective, including reference to relevant research

EATING DISORDER • Psychological explanations of ONE eating disorder i.e. Anorexia Nervosa, Bulimia Nervosa, Obesity.• Biological explanations including, neural and evolutionary explanations for ONE eating disorder for example anorexia nervosa, bulimia, obesity

• explain one eating disorder from at least two psychological perspectives•D & E psychological research into ONE eating disorder•Evaluate the usefulness of two psychological explanations of ONE eating disorder•D& E biological explanations of ONE eating disorder•D & E research into neural and evolutionary explanations of one eating disorder

Relationship with food

EATING BEHAVIOUR:1. Factors influencing attitude to food and eating

behaviour2. Explanations for success or failure of dieting

FACTORS INFLUENCING ATTITUDE TO FOOD AND EATING BEHAVIOUR

• What are the attitudes to food?

• Represent comfort

• Distraction from boredom

• Todhunter (1983) Food is prestige, status and wealth – communication i.e. apple for teacher, affection, etc

• CORE COGNITONS OF FOOD:

• Self-efficacy – I am confident I eat healthy

• Costs – eating makes me fat

• Benefits – makes me healthy

• ROLE OF LEARNING:

• 1. Babies born with taste receptors for sweet, sour, bitter tastes. Identify what they like/dislike from young age

• 2. experiences and familiarity increase food preferences Birch and Marlin (1982) exposure of two year olds to new food over 6 weeks increased preference for that food (minimum 8-10 exposures)

• 3. Birch (1999) born with innate ability to associate food tastes and smells with consequences of eating that food

• PARENTAL ATTITUDE

• Mothers attitude to food will affect child’s preferences – Olgen (2007) significant correlation between diet of mum & child

• Peers and Modelling – increase consumption of eggfruit (Lowe et al, 1998). TV make food attractive. Advertised food high in fat and carbs

• Parents use operant conditioning, rewards. For disliked food (i.e. have ice cream if eat veg) works in short term but Long term increases desirability of reward food and decrease liking for non-preferred food (Birch, 1999)

FACTORS INFLUENCING ATTITUDE TO FOOD AND EATING BEHAVIOUR

• What are the attitudes to food?

• CORE COGNITONS OF FOOD:

• ROLE OF LEARNING:

• PARENTAL ATTITUDE• Mothers attitude to food will affect child’s preferences – Olgen (2007) significant correlation between diet of mum

& child• Peers and Modelling – increase consumption of veg.fruit (Lowe et al, 1998). TV make food attractive. Advertised

food high in fat and carbs• Parents use operant conditioning, rewards. For disliked food (i.e. have ice cream if eat veg) works in short term

but Long term increases desirability of reward food and decrease liking for non-preferred food (Birch, 1999)

RESEARCH STUDY into factors influencing attitude to food:

• NICKLAUS ET AL (2004) (read and highlight p166 AQA textbook)

• What did the study show about food preferences for children aged 2-3 at nurseries

• What methodological evaluations could you make?

• Are there any evaluations of the study?

Cultural influences, mood and health concernsFactors influencing

attitude to food and eating behaviour

AO1

Culture •Wardle et al (1997)•Picca Indians of New Mexico vs. Americans•Flight et al (2008)•Stoneman and Brody (1981)•Religion•Liou and Contento (2001)

Mood •Sweet, starchy, carbs when low. •Due to CC, OC, SLT•Gibson (2006) The serotonin hypothesis•Macht and Dettmer (2006)•Smith et al (2003)•Warsink et al (2008)•Wolff et al (2000)

Health •Government eating plan

EVALUATIONS:

• Research on mood states that comfort foods should display nutritional information to stop depressed people eating badly, such habits can contribute to becoming bulimic

• Eating behaviour can be seen an inter-relation of internal variables such as sensory qualities and external variables such as social context. Suggesting that it is the influence of several factors that act with each other that determines attitudes and behaviour

• Findings from research could be used to create eating programmes• Nature and nurture cannot be separated. They are combined such

as the effects of learning experiences and innate food preferences• Have to take into account social environment, personality and

amount of health messages people receive and how they process the information.

Culture, mood and health concerns – teacher notesCULTURE:Wardle et al (1997) surveyed the diets of 16,000 young adults across 21 European countries. In general eating a basic and healthy diet was low with females. Males did better. -People in Sweden, Norway, Denmark and Holland ate most fibreItaly, Portugal and Spain ate most fruit (less in Scotland and England)Polish and Portugal high salt intake. ‘Mediterranean diet’ lower level heart disease and obesityKey diffs in diet were that used olive oil (unsaturated fats), high levels of fruit and veg, moderate levels of dairy products eaten, moderate levels of fish and poultry, low levels of red meat and low intake of wine. Low processed food and more natural products.•Pica Indians of New Mexico those who stay in their communities have low levels of obesity. Those who move to areas heavily influenced by American Culture and diet develop high levels of obesity •Flight et al (2008) compared two groups of Australian high school students aged 12-18 from remote rural areas and cosmopolitan city areas. The city students exposed to cultural diversity than rural students and more familiar with different foods and more willing to try different food (less neophobic – i.e. willing to try novel food)•Stoneman and Brody (1981) found children expressed preference for foods advertised when children more similar to them racially than different•Religion – dietary laws based on religious writings and fundamental beliefs. Many religious customs and laws can be traced to early concerns for health and safety in eating foods, Preservation methods such as freezing not available. Jewish law - can’t eat animals that do not have cloven hooves such as pigs and rabbits and lobsters, shrimps. Islam follows rules of Halal- Hindus and Sikhs do not eat beef•Liou and Contento (2001) Chinese- American women investigated. found that the degree of acculturation in terms of accepting and conforming to US norms was reflected in food preference with less acculturated women maintaining a traditionally Chinese diet. •---------------------•MOOD:•Many people crave sweet, starchy, crabs when feeling low.- called comfort eating. Due to CC – learned association with feeling low and compensating by eating chocolate or other sweet food. OC – associated feelings of happiness or pleasure even if these are temporary and SLT- chocolate marketed as product of bringing happiness and we see choc as reward and reward ourselves in same way.•Gibson (2006) The serotonin hypothesis: carbs such as choc contain amino acid ‘tryptophan’ used by brain to make serotonin. Low levels associated with dep and makes our mood better for short term.•Macht and Dettmer (2006) studied mood change in relation to eating choc or an apple. Both raised mood and reduced hunger but choc was more powerful. Led to happy but guilty feelings.•Opiate hypothesis – have opiate neurotransmitter. i.e. Beta-endorphin. Can produce pleasurable feelings and euphoria. Sweet foods increase the release of endorphins in the brain•Smith et al (2003) looked at the effects of caffeine on mood and cognitive performances and found two normal strength coffee increased mood, alertness and concentration, general task performance and memory

Teacher notes•Wansink et al (08) offered popcorn and grapes to pp. Watching a sad film ate more popcorn to cheer self up and ate more grapes during a comedy to prolong their mood•Wolff et al (2000) female binge eaters had more negative moods on binge eating days compared to normal female eaters. Suggesting negative moods related to abnormal eating practices

•HEALTH:•The government and health professionals have produced guideline as to what constitutes as a healthy diet. Includes carbs, whole grain, fruit and veg, protein, oily fish, limited amounts of sugary, fatty and salty foods.•Eating plan reduce risk of heart disease, stroke, high BP, some cancers and Type 2 diabetes•(p116-118 of Erika Cox textbook)

Knowledge and understanding• DESCRIBE TWO EXPLANATIONS OF THE ORGIINS OF ATTITUDES TO FOOD AND EATING BEHAVIOUR•OUTLINE 4 CRITICAL POINTS INCLUDING SYNOPTICITY•Discuss attitudes to food and or eating behaviour (25)

EXPLANATIONS FOR THE SUCCESS OR FAILURE OF DIETING:

• Why do so many people want to lose weight? (Ogden, 2007)- Media influence – images in the media (especially for

women) become more slimmer over the last 50 years- Family – mothers may act as model for body dissatisfaction

or a product of the r’ship- Ethnicity – Black and Asian women being exposed to

western media and more eating disorders- Social Class- eating disorders frequent in higher class- Peer-groups- reinforcement, dieting a norm for the group and

praise seen as a reward.

Success or failure of dieting

weightwatchers

Explanations for the success or failure of dieting

• WHEN DIETING IS SUCCESSFUL• Kirkley et al (1988) assessed the eating style of 50 women using dietary self monitoring forms for four days and reported

that restrained eaters consumed fewer calories than unrestrained eaters. Similarly, found that interventions involving strategies such as calorie-controlled diets, cognitive behavioral therapy or healthy eating can result in changes in eating behavior and weight in first few months (Wadden, 1993)

• Motivational style seen as psychological variable for weight loss (Williams, 1996). Kiernan et al (1988) found individuals who were more dissatisfied with their body shape at baseline were more successful – attractiveness was seen as a key point

• Ogden (2000) investigated psychological differences between weight loss regainers (stable obese) and weight loss maintainers (had been obese) Weight loss maintainers had a psychological model of obesity associated with low self-esteem and depression. Motivated to lose weight for psychological reasons, such as wanting to boost self-esteem.

• Ogden and Hills (2008) interviewed people who had successfully lost weight and maintained weight loss and reported that much weight loss was triggered by key life events such as divorce/illness

• Thomas and Stern (1995) found that financial incentives did not promote significant weight loss or help maintain weight loss. Did find that creating group contacts does have some success, suggesting that social support has a motivational role to play – positive reinforcement

• Miller-Kovach et al (2001) reported that social support methods offered by weight watchers significantly superior to individual dieting regimes over a period of 2 years. Creates the social network which is the motivational device

• Lowe et al (2004) found an average of 71.6% of weight watchers members maintained a body weight loss of at least 5%.• Bartlett (2003) dieting success occurs best with target of reducing calorific intake of between 500-1,000 calories a day,

resulting in weight loss of about one to two pounds a week. Supporting idea that achievable goal setting is a strong motivational force

• Wing and Hill (2001) reported common behavior that led to successful weight los and its maintenance included a low fat diet, constant monitoring of food intake and weight & exercise

Explanations for the success or failure of dieting

• WHEN DIETING IS SUCCESSFUL• Kirkley et al (1988)

• . Similarly, found that interventions involving strategies such as calorie-controlled diets, cognitive behavioral therapy or healthy eating can result in changes in eating behavior and weight in first few months (Wadden, 1993)

• Motivational style seen as psychological variable for weight loss (Williams, 1996).

• Kiernan et al (1988)

• Ogden (2000) investigated psychological differences between weight loss regainers (stable obese) and weight loss maintainers (had been obese) Weight loss maintainers had a psychological model of obesity associated with low self-esteem and depression. Motivated to lose weight for psychological reasons, such as wanting to boost self-esteem.

• Ogden and Hills (2008)

• Thomas and Stern (1995) found that financial incentives did not promote significant weight loss or help maintain weight loss. Did find that creating group contacts does have some success, suggesting that social support has a motivational role to play – positive reinforcement

• Miller-Kovach et al (2001) reported that social support methods offered by weight watchers significantly superior to individual dieting regimes over a period of 2 years. Creates the social network which is the motivational device

• Lowe et al (2004)

• Bartlett (2003) dieting success occurs best with target of reducing calorific intake of between 500-1,000 calories a day, resulting in weight loss of about one to two pounds a week. Supporting idea that achievable goal setting is a strong motivational force

• Wing and Hill (2001)

Explanations for the success or failure of dieting

• WHEN DIETING IS A FAILURE:• Jeffrey (2000) found that obese people tend to start regaining weight after 6 m due to failure to maintain behavioral

changes, suggesting that factors like loss of motivation and social pressure have negative influences• Cummings et al (2002) found low calorie diets stimulate appetite by increasing ‘ghrelin’ production by 24% reducing

chance of losing weight. The success of stomach reduction surgery may be due to reduced stomach producing less ghrelin

• Williams et al (2002) found people who lack concentration are often unsuccessful with diets as they lose focus on targets and strategies, indicating that cognitive factors play a role in failure

• D’Anci et al (2008) found it is low-carb diets that have cognitive effect reducing glycogen levels causing lack of concentration. Suggesting certain types of diet influence cognitive factors

• THE BOUNDARY MODEL – Herman and Polivy (1984) hunger keeps intake of food above minimum and satisfaction (satiety) works to keep intake below maximum levels. Dieters tend to have larger range between hunger and satisfaction and takes them longer to feel hungry and more food to satisfy them. Restrained eaters will have self-imposed desired intake and once they go over this boundary, they will continue to eat until satiety.

• THE ROLE OF DENIAL – attempting to suppress will have opposite effect. Wegner et al (1987) asked pp not to think about the white bear but to ring a bell if they did and others to think about the bear. Results showed that those told not to think about the bear rang the bell more often

• Psychological factors are important in dieting. Wing et al (2008) found people suffering from depression more likely to regain any weight lost. Adam and Epel (2007) suggested that stress could also play a role. Stress hormones encourage the formation of fat cells. A restricted-calorie diet is itself a stressor and one reason why it may be difficult to adhere to a diet is our use of food to deal with stress, the emotional eating. Chocolate high in calories but produces endorphins. Reducing feelings of stress. Association between certain foods (such as chocolate) have been learned and when sad associated with feelings of security. Counter-productive when trying to lose weight.

Explanations for the success or failure of dieting

• WHEN DIETING IS A FAILURE:• Jeffrey (2000) found that obese people tend to start regaining weight after 6 m due to failure to maintain behavioral

changes, suggesting that factors like loss of motivation and social pressure have negative influences• Cummings et al (2002) found low calorie diets stimulate appetite by increasing ‘ghrelin’ production by 24% reducing

chance of losing weight. The success of stomach reduction surgery may be due to reduced stomach producing less ghrelin

• Williams et al (2002)• D’Anci et al (2008) found it is low-carb diets that have cognitive effect reducing glycogen levels causing lack of

concentration. Suggesting certain types of diet influence cognitive factors• THE BOUNDARY MODEL – Herman and Polivy (1984) hunger keeps intake of food above minimum and satisfaction

(satiety) works to keep intake below maximum levels. Dieters tend to have larger range between hunger and satisfaction and takes them longer to feel hungry and more food to satisfy them. Restrained eaters will have self-imposed desired intake and once they go over this boundary, they will continue to eat until satiety.

• THE ROLE OF DENIAL – attempting to suppress will have opposite effect. Wegner et al (1987) asked pp not to think about the white bear but to ring a bell if they did and others to think about the bear. Results showed that those told not to think about the bear rang the bell more often

• Psychological factors are important in dieting. Wing et al (2008) found people suffering from depression more likely to regain any weight lost. Adam and Epel (2007) suggested that stress could also play a role. Stress hormones encourage the formation of fat cells. A restricted-calorie diet is itself a stressor and one reason why it may be difficult to adhere to a diet is our use of food to deal with stress, the emotional eating. Chocolate high in calories but produces endorphins. Reducing feelings of stress. Association between certain foods (such as chocolate) have been learned and when sad associated with feelings of security. Counter-productive when trying to lose weight.

EVALUATION OF DIETING• Ethical concerns with types of research as it can be restricted. E.g. Setting up experimental

designs can be problematic and have to use self-reports (this is not always reliable as having to rely on memory)

• Individual differences contribute to success rates i.e. Low-restrainers find dieting easy but high restrainers find it difficult

• Mensink et al (2008) high restrainers hyper sensitive to food cues, likely to abandon diets. Stirling et al (2004) found high-restrainers could not resist forbidden chocolate. Not know whether being high or low restrainers is innate or learned

• Research findings can assist with identification of successful dieting and address growing issue of obesity

• Nolen-Hoeksema (2002) found females on low-fat diets develop negative mood which is dealt with over eating with 80% developing clinical depression within 5 years. Suggesting dieting can lead to serious risk of developing mental disorders

• Number of genetic mechanisms influence on weight. The gene LPL (if too much produced) stores calories but also makes it easier to regain lost weight.

• Research suggests some cultural groups find it harder to diet successfully because of natural inclination to obesity. Park et al (2001) Asian children and adolescents have greater central fat mass when compared with Europeans and other ethnic groups

Diagram of the human body: Label the parts of the body responsible for eating behaviour and satiation.

Hypothalamus:

LH and VMHPituitary gland

Homeostasis mechanism

Liver

Digestive tract

BIOLOGICAL EXPLANATIONS OF EATING BEHAVIOUR:

1. The role of neural mechanisms involved in controlling eating and satiation

2. Evolutionary explanations of food preferences

Which area is responsible for eating behaviour?

THE ROLE OF NEURAL MECHANSIMS INVOVLED IN CONTROLLING EATING AND SATIATION

THE ROLE OF NEURAL MECHANSIMS INVOVLED IN CONTROLLING EATING AND SATIATION

• (LH) (VMH)

THE ROLE OF NEURAL MECHANSIMS INVOVLED IN CONTROLLING EATING AND SATIATION

• Hetherington and Ranson (1942) demonstrated lesions of an area in the hypothalamus of the brain caused rats to overeat and become obese.

• Area of the hypothalamus which had the lesion by which the rats became obese is called the VMH (ventromedial hypothalamus) Assumed it was the satiety centre (its function to tell us when we are full and to stop eating)

• Another area of the hypothalamus is called the Lateral hypothalamus (LH) led to loss of feeding behavior (aphagia) in rats when they had lesions made. Suggesting that this area is the feeding centre

• Stellar (1954) found if stimulated the VMH then decreased eating but with lesions it increased. Showing evidence of two brain areas are the feeding and satiety centre.

• Shaunghoti and Samranvej (1975) found a tumour destroyed the VMH who exhibited over eating (supporting animal studies)

• Empty stomach sends signals to brain to start eating. These signals may include direct neural pathways form the stomach to the brain, an important role is played by a hormone ‘Gherlin’ Hormone is secreted from stomach and the amount released is proportional to the emptiness of the stomach. Gastric bands reduce ghrelin secretion from the stomach

• Cummings et al (2004) investigated changes in blood ghrelin levels over time between meals. Found levels fell immediately after eating lunch. 70 mins reached their lowest level. Slowly began to rise peaking at evening meals. Closely correlated with levels of hunger.

THE ROLE OF NEURAL MECHANSIMS INVOVLED IN CONTROLLING EATING AND SATIATION

• Feeding is not under strict biological control. People eat more of tastier food and when eating in company of others (de Castro, 2004)

• Hormone CCK (cholectystokinin) signals satiety to the brain. Smith et al (1982) injections of CCK in animals reduced meal size

• Blood glucose levels key signal to brain falling when hungry and rising as we eat. They respond rapidly to food intake. However, glucose levels do not vary much and not enough to be an effective signal for hunger and satiety. People with diabetes often have long-term levels of high blood glucose but most have normal appetites

THE ROLE OF NEURAL MECHANSIMS INVOVLED IN CONTROLLING EATING AND SATIATION

• Homeostasis is the mechanism by which biological variables including eating are regulated within limits i.e. When thirsty we drink, when we need food we experience hunger and makes us eat. It regulates the set point of the amount we can consume. It regulates fat stores, glucose levels. When our fat stores (lipostatic) are depleted or when our blood glucose (glucostatic) levels are low, we feel hungry which makes us eat

DIGESTIVE TRACT

• Digestive tract – breaks down food into essential components such as sugar and amino acids. The process begins in the mouth food mixes with saliva

• Saliva contains enzymes which break down complex sugars and converting proteins into amino acids

• After swallowing – food passes through the oesophagus into the stomach• From stomach it passes to the duodenum – small intestine• Glucose and amino acids absorbed into the bloodstream

INSULIN AND GLUCAGON

• The pancreas releases two hormones ‘insulin’ and ‘glucagon’

• Insulin controls blood glucose levels by allowing glucose in blood stream to enter the cells in the body

• Glucose maintain energy

• Glycogen stored in liver and in muscles and along with fatty tissues, makes up energy reserve for the body

• Diabetes – insulin levels are low. Due to damage to cells of pancreas gland that secrete insulin (type 1) and type 2 is when pancreas fails to secrete enough insulin.

Evaluations of biological explanations of eating behaviour

• Lesioned VMH rats initially overeat and gain weight. However, these effects are temporary and body weight stabilises.

• Findings of Lesioned LH rats cannot explain why rats go from not eating and drinking to gaining ability to eat. Therefore effects are temporary.

• Research has indicated that neural mechanisms involved are complex and perceiving the VMH as satiety centre and LH as hunger centre is too simplistic

• Lesions to the LH also produce disruptions to aggression levels and sexual behaviour

• Quaade (1971) found stimulating the VMH of obese people made them feel hungry and results similar to those of rats and can generalise some findings on to humans

• However, raises problems when looking at neurotransmitters as lot of research based on non-human animals. Can we generalise from animals to humans? There will be a subtle difference in the control of feeding between humans and animals.

• The explanation plays a key role in explaining the regulation of human eating behaviour. Relevant to normal regulation and to eating disorders

• The biological approach is reductionist, focusing only on biological systems regulating food intake and body weight. Ignores psychological, social and cultural factors that influence our eating behaviour.

Break down the components/ingredients/nutrients of the following foods

HAMBURGER FRENCH FRIES

CHOCOLATE CAKE

EVOLUTIONARY EXPLANATIONS OF FOOD PREFERENCE

• THE ENVIRONMENT OF EVOLUTIONARY ADAPTATION

• EEA refers to environment in which species first involved

• Natural selection favored adaptations geared toward survival

• Lived in hunter gatherer societies

• EARLY DIETS

• Animals and plants

• Fatty food

• Now, still concerned with foods rich in calories

• EEA calories not plentiful

• PREFERENCE FOR MEAT

• Compensate for decline in plants

• Milton (2008)

• Essential minerals

• TASTE AVERSION

• Rat studies

• Garcia (1955)

• ADAPTIVE ADVANTAGE OF TASTE AVERSION:

• THE MEDICINE EFFECT

EATING DISORDERS:1. Psychological explanation of ONE eating disorder –

OBESITY2. Biological explanations, including neural and evolutionary explanations for ONE eating disorder -

OBESITY

OBESITY

http://www.youtube.com/watch?v=Q9Udj2QfO_UNOTE: Obesity is included in the ICD-10 but not in the DSM-IV as it has not been established that it is consistently associated with a psychological

or behavioural syndrome (APA, 2000)

ICD = International Classification of Diseases

DSM= Diagnostic and Statistical Manual of mental disorders

• 1 in 2 adults in the US were either overweight or obese in the 1990s (Tataranni, 2000)

• In the UK there is an upward trend in obesity– 1\2 women and 2\3 men are either overweight or

obese• Obesity shortens life by an average of 9 years (National

Adult Office, 2001)• Mokdad et al (1999) refer to an “obesity epidemic”

Obesity – the facts

• The World Health Organization increases risks of– Type 2 diabetes– High blood pressure– Reduced life expectancy

• Masso-Gonzalez (2009) estimated the incidence of diabetes in the UK between 1996 and 2005– Type 1 was constant– Type 2 increased from 46% to 56%

Obesity – the facts (cont.)

• Most common ways to define obesity are – BMI (Body Mass Index) – Waist circumference– Measuring thickness of fatty tissue using callipers

What is obesity?

• BMI is calculated dividing a person’s weight by their height squared

• BMI of less than 18.5=underweight• BMI over 25=overweight• BMI over 30=obese• BMI over 40=morbidly obese• http://www.nhlbisupport.com/bmi/ • ISSUES with BMI: doesn’t take into account

the ration between fat and muscle

BMI (Body Mass Index)

• PSYCHOLOGICAL, BIOLOGICAL AND EVOUTIONARY EXPLANATIONS OF OBESITY• EXPLANTIONS• AO1• RESEARCH STUDIES• EVALUATIONS• PSYCHODYANMIC• Unresolved conflicts, such as emotional deprivation during the oral stage. Libido becomes locked on to oral gratification. Obesity also linked to other factors explained by this approach such as depression• Felliti (2001) reported on five cases of sleep-eating obesity (eating food while asleep) all had suffered childhood abuse and their behaviour interpreted as unconscious anxiety reducer, backing up the theory• Most obese people have not suffered abuse – can only account for few cases• Obesity has grown into epidemic- but no evidence it is due to unresolved childhood conflict• Cases of depression linked to obesity may actually be an effect of obesity rather than a cause• BEHAVIOURAL• Obesity seen as maladaptive, learned behaviour occurring through overeating: • CC – naturally associated with pleasure and food cues• OC – food used as reward and reinforce for desirable behaviour• SLT – caused by observation and imitation of obese role models• Foster (2006) reports that treatment based on CC are successful as they help patients identify cues triggering inappropriate eating and then learn new response to them – could be due to CC• Jackson (2008) reinforcing children for eating creates compulsion leading to obesity. OC in childhood to blame.• Treatments based on CC create specific goals. Wing et al (2002) found such treatments incur average weight loss of 15.6kg in 18 months. So it does work!• SLT treatments are short term indicating other psychological and biological explanations should be considered• COGNITIVE• Maladaptive thought process with information processing having an elevated focus for food related stimuli• Braet and Crombez (2001) obese children hypersensitive to food related words, suggesting that information processing bias for food stimuli, leading to obesity• Cserjesi etal (2007) examined cognitive profiles of obese boys and found deficient attention span. Therefore involves cognitive deficits • Elias (2003) found early onset, long-term obesity leads to decline in cognitive functioning. Weakens the cause of obesity• Success of therapies using cognitive approach suggests cognitive factors may be involved in developing obesity• O’Rouke (08) CBT improved weight loss• BIOLOGICAL: GENETIC• Some genetically predisposed to becoming obese and having multiple genes linked to obesity• Frayling et al (07) people with two copies of the fat mass and obesity gene had 70% of becoming obese, while those with one had 30% chance. Supporting idea of multiple genes increasing the chances of being obese• Wardle et al (08) assessed twins on BMI and body fat deposits and found heritability figure of 70% suggesting genetic factors as having influence on obesity• Most cases cannot be explained by genetics alone. Genes do not determine obesity, environment is needed to express themselves• Genes have not changed but environment has like the availability of foods• Musani (08) obese people may be more fertile and reproduce more and increase genes favouring obese population•  • BIOLOGICAL: NEURAL• Hypothalamus playing key role in regulation of eating. Associated with development of obesity also linked is the role of hormones and neurotransmitters• Freidman (05) two neurons in hypothalamus (NPY and POMC) regulate appetite and play role in weight. Neurons are controlled by leptin. obese people produce leptin but its ability to suppress POMC is blocked (POMC decreases appetite) and their appetite remains high and they gain weight up to

point thought to be genetically determined• Stice et al (08) fewer dopamine receptors in brain. Tend to overeat to compensate.• Linking dopamine to obesity is correlational not clear if dopamine is a cause or effect of being obese• Hoped that leptin injections is effective treatment for obesity but only work for few people – doubt on importance of leptin role• Animal studies• BIOLOGICAL HOROMONAL• Insuling directs the storage of energy. Cortisol has powerful metabolic effect and Gherlin stimulates eating• Epel (01) women with high cortisol overeat sweet foods. Suggesting a role for cortisol in increasing body weight• Shintani et al (01) found action of gherlin does not have direct influence but is caused by production of leptin• Unclear whether abnormal levels of cortisol are cause or effect of obesity• Evidence suggest that hormonal factors play a contributory role in developing obesity rather than being direct cause• EVOLUTIONARY• Over eating habits more suited to the EEA where food was not universally available. We evolved to find high calorific foods desirable and store excess energy for times of scarcity. Evolved to minimise physical activity to store fat . Therefore, we are not suited to a world of ever-available foods. We

may be vulnerable to over-eating foods that not part of our evolutionary past because they do not trigger neural mechanisms that control appetite• THRIFTY – GENE HYPOTHESIS: selective advantage for people with insulin resistance as they would have been able to metabolise food more efficiently. Advantageous when scarcity of food but now lead to obesity due to ever ready food• Dimeglio and Mates (2000) found pp put on more weight when given liquid calories rather than solid calories. Backs up idea that we are not shaped by evolution to cope with liquid calories• Rowe et al (07) studied genetics of modern day Pima Indians who had high levels of obesity and concluded they have thrifty metabolism that allows them to metabolise food more efficiently. • Friedman (1994) studied the islanders of Kosrae where obesity levels have rocketed. Concluded thrifty gene well represented in times of less food but can cope with abundant amount of food. • Plausible explanation for modern day obesity and why people find losing weight difficult. Bodies are designed to consume as much and store as fat• Genetically determinist and seeing no other factors. But is not reductionist as recognises the mixture of genetics and environment• Thrifty gene hypothesis can explain why people who do not have the gene can eat lots and not put on weight.•  

• Emotional and restrained eating

• Binge-eating disorder

• Food addiction

• Night eating syndrome

• Psychological factors affecting physical activity

Psychological explanations to obesity

• Behaviourist explanation: food is associated with stress control

• Emotional arousal =>dishinibition of restraint=>emotional eating

• Heatherton (1993) suggests that overeating constitutes an escape from self-awareness in response to emotional pain

• Emotionality theory of obesity (Schachter, 1968)– People who become obese eat for emotional reasons– Thin people eat for hunger

• Overeating (hyperphagia) and under-eating (hypophagia) were also considered a way of managing emotions by Bruch (1965)

• ‘Restraint theory’ (Herman&Mack) shows how overeating might actually be caused by restained eating

• Psychodynamic: denial – “theory of ironic processes of mental control” (Wagner,1994) – WHITE BEAR!

Emotional and restrained eating

+Polivy&Herman (1999) told women they had passed\failed a cognitive test – those who had failed chose to eat as much as they liked

-there is contrasting evidence on the link between stress and eating

+Verplanken et al. (2005) correlational analysis on mood, impulse buying and snack consumption– Those with low self-esteem were more likely to

impulse buy and also consume snacks– Possibly this behaviour is an attempt to cope with

the emotional distress caused by low self-esteem

Emotional and restrained eating - evaluation

-Today it is believed that many people eat in response to their mood, regardless of their size

+Herman&Mack “preload\taste-test” confirms retraint theory

+ this helps explain why many people tend to regain weight after dieting

-not all dieters regain weight (Ogden, 2000)-issues with causality: overeating might be the

cause of low mood rather than the consequence!!

Emotional and restrained eating – evaluation (cont.)

• Approaches– alternative explanations (eg social; cognitive)– Cognitive approach: motivation CAN reflect action (social

cognition models)– Social approach: importance of cultural factors and availability

• Issues– Ethical issues – causing guilt in obese individuals + issues with

preload\taste-test– Gender bias

• Debates– Free will vs determinism– Nature vs nurture

• AO3– Lack of ecological validity (artificial setting)– PPs mostly females (lack of generalisability)

Emotional and restrained eating –IDAs and AO3s

• Eating an objectively large amount of food while experiencing a subjective sense of lack of control

• Usually develops during late adolescence or early adulthood

• It is usually associated with high levels of depression, low self-esteem and body dissatisfaction

Binge-eating disorder

• Wardle (1999) behind the food addiction model of obesity is a model of addiction – Exposure to a substance => changes to the CNS– This explains withdrawal symptoms and craving

• Behaviourist approach: eating is maintained as a consequence of negative reinforcement associated with the avoidance\relief of withdrawal symptoms

• Eating a small amount of the addictive food can trigger a binge...

• Carbohydrate craving hypothesis• Although obese people don’t seem to eat necessarily

more carbohydrates, but have a preference for sweet, fatty foods

Food addiction

• Stunkard et al (1955)– Evening hyperphagia: consumption of at least 1\4 of

total daily calories after evening meal– Insomnia (especially difficulties falling asleep)– Morning anorexia (no breakfast)– Recurring awakenings and failure to fall back asleep

without eating or drinking• NES seems to be more common in obese people than

the general population• BUT there is little evidence of a relationship between

NES and obesity

Night eating syndrome (NES)

• It is unclear whether reduced physical activity is a cause or a consequence of obesity

• Psychosocial factors implicated with lack of exercise:– Perceptions of competence– Fear of displaying body in a public setting

• Other reasons might be lack of opportunities\need – eg using car and public transport + tv - p.181

book Prentice&Jebb (1995)– Move from agricultural to industrial society

Psychological factors influencing physical activity

• Rissanen et al. (1991) examined the association between levels of physical activity and excess weight gain of 12000 adults over 5 years – Results: lower levels of activity were a greater

risk factor for weight gain than any other baseline measure!

– BUT there could be a 3rd factor involved (e.g those with low activity were women with young children so that could explain weight gain...)

Psychological factors influencing physical activity (cont.)

• Cross-sectional design used to investigate exercise\obesity (compare obese vs non-obese people)

• Bullen et al (1964) used time-lapse photography to observe obese vs normal-weight girls on summer camp– Obese girls spent more time floating than swimming– Obese girls were inactive for 77% of time when

playing tennis (vs 56% normal weight girls)

Psychological factors influencing physical activity (cont.)

EVALUATIONS OF PSYCHOLOGICAL EXPLANATIONS OF OBESITY:

• ROLE OF BEHAVIOUR: psychological explanations of obesity emphasize the role of behaviour and highlight under activity and overeating

• INCREASE IN PREVALENCE OF OBESITY: can account for the significant rise of obesity

• DIFFERENCES IN OBESITY RATES BY COUNTRY: help explain differences between different countries

• INTERVENTIONS: provide theoretical frame work to help lose weight• CROSS-SECTIONAL STUDIES: much research on physical activity

and eating behaviour uses cross sectional design (measuring behaviour and weight) unclear what comes first. Does obesity cause inactivity or vice versa

• FOOD INTAKE MEASUREMENT: measuring food intake is difficult because eating changes in accordance to the situation and way it is assessed. Problematic to assess accurately how much people who are obese are actually eating

• GENETIC PREDISPOSITION TO OBESITY: sound evidence of genetic predisposition. But unclear how it influences eating behaviour

BIOLOGICAL EXPLANATIONS OF OBESITY

•Genetic theories•Neural model of obesity•Evolutionary model of obesity

Genetic theories• Family clusters

– If one parent is obese, 40% chance of child being obese– If both parents are obese, 80%– Probability of thin parents producing obese offspring is only 7%!

• Twin studies– MZ twins reared separately are more similar in weight than DZ twins

reared together!!!– Stunkard et al (1990) examined the BMI of 93 pairs of MZ twins reared

apart and found that genetic factors accounted for 66-70% of variance in body weight

– HOWEVER, role of genetics seems stronger in lighter twin pairs than in heavier ones

• Metabolic rate theory– ‘resting metabolic rate’ s highly inheritable– Tataranni et al (2003) – page 185 book- study on Pima Indians

• Appetite regulation

• Appetite control may depend on a genetic predisposition

• A gene connected with profound obesity in small animals has been identified BUT still unclear for humans

• Montague et al (1997) two children have been identified with a defect in their ‘ob gene’, which produces leptin – They were given daily injections of leptin– They lost 1-2 kg per month

Genetic theories – appetite regulation

• Possible neurochemical imbalances cause overeating

• Recent research suggests that body fat might be an active organ and may trigger hunger itself

• This would mean that once individuals start gaining excess weight, they then feel more hunger and become less sensitive to satiation signals

Neural model of obesity

• Could storing excess body fat be an adaptive response?• ‘Thrifty gene’ hypothesis (James Neel)• http://www.independent.co.uk/news/science/scientists-link-obesity-to-thrifty-

gene-of-our-ancestors-596874.html • People from Africa, South-east Asia and Polynesia are especially prone to

obesity because they are more likely to have inherited the genes that encourage the storage of fat, Jeffrey Friedman, an obesity specialist at the Rockefeller University in New York, writes in the journal Science.

• Professor Friedman says that the difference in obesity rates between ethnic groups could have something to do with their respective genetic histories. "For people who lived in times of privation, such as hunter-gatherers, food was only sporadically available and the risk of famine was ever- present.

• "In such an environment, genes that predispose to obesity increase energy stores and provide a survival advantage in times of famine. This is the so-called thrifty gene hypothesis," he says.

Evolutionary model of obesity

+explain why obesity often runs in family+simple, effective explanations+there is evidence for certain ethnic groups being more

predisposed to obesity+reduce the risk of stigmatisation of obese individuals-BUT might reduce effectiveness of dieting-doesn’t explain why obesity is on the increase today,

whereas our gene pool has remained constant-doesn’t explain why geographical relocation to

obesogenic environment often causes individuals to gain weight

-it is still unclear how genes are involved in obesity and to what extent...

Biological explanations - evaluation

• Free will vs. determinism

• Nature vs. nurture

• Low generalisability of case studies

• Issues of extrapolation

• Compare biological approach to behaviourist, social learning, cognitive

Biological explanations - IDAs