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OBESITYNOTE: 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)

“ has identified obesity as one of the major chronic diseases that increases risk of non communicable diseases such as type 2 diabetes and high BP”

http://youtu.be/8HSqE1U_m_0

http://youtu.be/TyUu0EUjD-s

Watch the following clip...

1. What is obesity?2. Why are so many people obese?3. Who is most and least likely to be obese?4. How can you determine whether you are

obese?5. When are you considered underweight,

overweight and obese according to your BMI?

6. What are the consequences of obesity?

Quiz time!!

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 (Must et al 1999)

Masso-Gonzalez (2009) estimated the incidence of diabetes in the UK between 1996 and 2005 aged 10-79◦ Type 1 was constant◦ Type 2 increased from 46% to 56%

Obesity – the facts (cont.)

1980- 6% men and 8% women, by 1997, 17% and 21%

Chinn and Rona (01)- English children 50% more obese compared to results in 1994

Highest rates of obesity- USA, Saudia Arabia, Tunisia and Canada

How common is Obesity?

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/

BMI (Body Mass Index)

Adominal fat rather than lower body fat can predict incidence of health problems

Lean et al (1998)- weight reduction recommended when waist circumference:

greater than 102cm in men (40 inches) greater than 88cm (35 inches) in women

Waist Circumference

What are the problems with

BMI as a measure of

obesity?

Psychological Explanationsto obesity

How would the psychodynamic, behavioural and

cognitive approach explain

obesity??

Behaviourist explanation of Obesity

Seen as a maladaptive, learned behaviour occurring through overeating in 3 ways:

1. Classical conditioning2. Operant conditioning3. Social learning theory

Matching time...

2. Operant conditioning

1.Classical conditioning

B. Obesity occurs by the observation and imitation of obese

role models

A. Obesity occurs due to food being used as

a reinforcer for desirable behaviour

3. Social learning theory

C. Obesity occurs because food is

naturally associated with pleasure and food

cues come to be associated with a

pleasurable response

Foster (2006): found treatments based on CC are successful as they help patients identify cues triggering inappropriate eating and then learn new responses to them

Jackson (2008): reinforcing children for eating creates compulsions leading to obesity, OC in childhood is to blame

Hardeman et al (2000): treating obesity by role models encouraging healthy lifestyles led to significant weight loss

Research

Wing et al (2002): treatments based on CC incur average weight loss of 15.6 kg in 18 months....it works!!

Devlin (1995): treatments based on OC resulted in weight loss not being maintained

Weight loss after SLT treatments tend to be short term, suggesting that other explanations should be considered

A02

food is associated with stress control

Emotional arousal =>dishinibition of restraint “ what the hell!”=>emotional eating

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

Emotional eating

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)

Emotional 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

Evaluation

+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

-issues with causality: overeating might be the cause of low mood rather than the consequence!!

Evaluation

How can we evaluate behaviourism according to...

ISSUESDEBATES

APPROACHESAO3

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

(social cognition models)◦ Social approach: importance of cultural factors and

availability Issues Gender bias Debates

◦ Free will vs determinism◦ Nature vs nurture

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

IDAs and AO3s

Unresolved conflicts, e.g. Emotional deprivation during the oral stage

Libido becomes locked onto oral gratification

Psychodynamic explanation of obesity

Linked to poor childhood experiences

Felliti (2001)- reported 5 cases of sleep eating obesity all had suffered from abuse in childhood

Behaviour as an unconscious anxiety reducer

Psychodynamic approach

Most obese people haven’t suffered abuse or indulged in sleep eating...cannot be only account

No evidence of a parallel rise in unresolved childhood conflict

Just ideas...cant prove or disprove

Evaluation

Food as a symbol of love- compensate for absence of love

Creates a circle of overeating

Psychodynamic approach to obesity

overweight

No loveovereat

Support for Freudian construct of mother love- loving bond established by mother and baby is through food

Breast milk is sweet and high in fat content

Overweight people eat food high in sugar/fat

Evaluation

Occurring as a result of maladaptive thought processes

information processing having an elevated focus for food related stimuli

Cognitive explanations of obesity

Brat and Crombez (2001)- obese children were hypersensitive to food related words, suggesting an info processing bias for food stimuli leading to obesity

Cserjesi et al (2007)- examined cog profiles of obese boys and found them deficient in attention capabilities, suggesting childhood obesity involved cognitive deficits.

Research

Cause and effect- Elias (2003) found that early onset, long term obesity leads to a decline in cog functioning

But successful therapies suggest cog

factors may be involved in developing obesity

O’Rourke (2008) found that CBT sig improved weight loss

Evaluation

Complete the gap fill task WITHOUT using your

notes

Biological explanations of obesity

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

Read the handout on the genetic

explanation of obesity and answer the

following questions

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) study on Pima Indians

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

How could we explain obesity according to the

neural explanation?

Hypothalamus has been associated with obesity

Abnormality in VMH

Reeves and Plum (1969): conducted post mortem on obese female

VMH had been destroyed

Evaluation?

Neural model of obesity

Friedman (2005) reported that 2 hypothalamic neurons regulate appetite

Key role in establishing weight NPY= starts eating POMC= stops eating Both controlled by Leptin In obese people, Leptin is unable to

suppress POMC, so appetite stays high and they gain weight

Neural model of obesity

Evaluation

Leptin injections could be an effective treatment in treating obesity

However, only works in a few people Casts doubt on the importance of Leptin

Neural model of obesity

Evolutionary model of obesity

Read the article and answer the

questions......How could evolution

explain obesity??

Our eating habits are more suited to the EEA where food was not universally available

Evolved to find high calorific foods desirable Store excess energy as fat for times of

scarcity Evolved to minimise physical activity to

preserve fat stores

Evolutionary model of obesity

Those individuals who were most energy efficient in terms of burning off excess energy and remaining thin would have been less successful

Evolutionary mechanisms would have favoured those who stored excess fats and were less efficient in burning it off= Aid survival!!

Thrifty Gene hypothesis (Neel, 1962)

How we have evolved is not suited to our sedentary world of ever available fatty foods

Vulnerable to overeating foods which were scarcely available in our evolutionary past

Environment no longer requires thrifty genes so this results in obesity, health problems, such as type 2 diabetes!

How does evolution explain obesity then?

Sedentary lifestyle is a medical term used to denote a type of lifestyle with no or irregular physical activity.[1] A person who lives a sedentary lifestyle may colloquially be known as a couch potato. It is commonly found in both the developed and developing world. Sedentary activities include sitting, reading, watching television and computer use for much of the day with little or no vigorous physical exercise. A sedentary lifestyle can contribute to many preventable causes of death.

+explain why obesity often runs in family

+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

Biological explanations - evaluation

- 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

Biological explanation of obesity

Metabolic rate

theory

Thrifty Gene

hypothesis

Ob gene

Ventromedial

hypothalamus