Transcript Eating Behaviour

Anorexia Nervosa (AN)
Symptoms & Cause
Specifications state: only cover one eating disorder
Video clips
There are many
fascinating films about
anorexia on You tube
Clinical characteristics of anorexia
nervosa (AN): DSM IV tr
First case reported in 1694
‘Nervous loss of appetite’. Named in 1870
Anorexics display an ‘abnormal’ attitude
towards food and eating.
It is primarily a female disorder, usually
occurring during adolescence.
It is characterised by a refusal to maintain
normal body weight.
Clinical characteristics of anorexia
nervosa (AN): DSM IV tr
4 criteria for anorexia:
1.
2.
3.
4.
Anxiety - sufferers fear gaining weight
Individuals need to weigh less than 85% of
their normal body weight to be diagnosed as
anorexic
The distorted body image is not evident to
anorexics themselves – they still see
themselves as fat
Amenorrhoea – for more than 3 months
Anorexia causes a general physical
decline
Cessation of menstruation
(amenorrhoea)
 Low blood pressure
 Dry and cracking skin
 Constipation
 Insufficient sleep
 Depression and low self-esteem
 Up to 20% cases of Clinical AN are fatal

A BMI of below 18.5 is an indicator & 15
is clinical
When does it change from a ‘Diet’ into a
‘Disorder’ (DSM IVr)?
When the BMI (Body Mass Index) is equal to or less
than 15
(when weight drops below 85% of expected weight by
height and frame)
However the BMI is only an indicator, it must be
accompanied by a distorted body image, an
abnormal relationship with food, a morbid fear of
gaining weight, cessation of periods (3 months) and
denial that there is a problem
Why is 15% such an important figure?
At puberty a 15% increase in body fat (‘puppy fat’) is
required to trigger the release of hormones
necessary for the development of secondary sexual
characteristics.
(Wider hips, breasts, periods, pubic hair etc)
What happens if you drop below 15 BMI?
Secondary sexual characteristic hormones
are no longer produced and the body
returns to pre-pubic child-like ‘asexuality’.
Narrowing of hips, cessation of periods, breasts
shrink, testicular atrophy (males) and these can be
permanent!
Behavioural symptoms
 Irritability
& difficulty interacting with
other people.
 Decrease in concentration levels
 Difficulty sleeping and fatigue during the
day.
 Compulsive and obsessive behaviours
around cleanliness, tidiness and exercise.
Behavioural symptoms continued…
 Obsessive about their
body/appearance.
 Obsessive about food/ fat/ calories.
 High academic achievers.
 Constant strive for perfection.
Physical symptoms
 Weight loss
 Dry/flaky skin
 Downy hair growing on the face, back and
arms.
 Hair thinning or loss.
 Brittle nails.
Medical complications of anorexia:
Slow heart rate
Low blood pressure
Arrhythmia
Constipation
Abdominal pain
Hormone imbalance
Slow thyroid function
Osteoporosis
Kidney failure
Anaemia
Loss of periods
Potential high risk of infection and suppressed
immunity
 Death
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Prognosis
 Variable – 20% have one episode and
recover completely, while 60% follow
an episodic pattern of weight gain
and relapse over a number of years
 Remaining 20% continue to be
affected and often require
hospitalisation
 Mortality rate of those admitted to
hospital is over 10% due to
starvation or suicide.
Explanations for Anorexia
The aetiology (cause & progression) of AN is
probably explained by a combination of different
factors including:
 Biological
 Psychological
 Familial
 Socio-cultural
In other words the diathesis-stress model
Genetic Predisposition +
Environmental Trigger = Disorder
AN Biological explanations...
1. There may be a genetic origin
Family studies have shown that firstdegree relatives of AN have an increased
risk of developing an eating disorder

Research in twins has shown that MZ have a higher
concordance rate than DZ twins for anorexia. Holland et
al (1984) found a 56% concordance rate in MZ twins, and
only 5% in DZ twins.
Biological approach
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Assumes our behaviour is controlled by the activity in
the CNS, specifically the brain.
The brain itself is organised into regions which have
different roles, so a malfunction in one region may
cause a behavioural problem in the individual.
Malfunctioning of the hypothalamus plays an important
role in the regulation of eating. Animal experiments
which involve lesions in a particular part of the
hypothalamus have led to either over-eating or
starvation in the animals.
Biological approach
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Neural mechanism dysfunction has been used as an
explanation for anorexia in humans.
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The lateral hypothalamus (LH) produces hunger and
the ventromedial hypothalamus (VMH) reduces
hunger.

A malfunction may be the cause of loss of appetite.
For some anorexics it is as if their VMH is jammed
on.
Biological explanations...
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Another explanation could be Imbalance of
serotonin neurotransmitters

Serotonin acts to suppress appetite
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Disturbances of the serotonin pathways within the brain have
been linked to the onset and maintenance of eating disorders.
In particular, it seems that increased serotonin activity in the
brain may be responsible for anorexic behavior.
There is considerable evidence that increased serotonin
activity in the brain is associated with appetite suppression. In
fact, drugs which act on serotonin pathways in the brain are
commonly used for the short-term management of obesity.
It has been suggested that food restriction and several other
behaviors which are characteristic of anorexia may be
associated with increased serotonin activity.
Bailer (2007)
Found higher serotonin activity in
women recovering from bingeeating/purging.
And the highest levels of serotonin
activity was found in women who
showed the most anxiety.
High levels of serotonin are
associated with jittery, anxious
feelings.
In order to get rid of these anxious
feelings – the person may stop
eating.
Suggestion is, that it is
the anxiety that triggers
Anorexia and that AN is
just a symptom of getting
rid of the anxiety.
If serotonin is implicated in anorexia
then this would have real world
application. It should be possible to
treat AN suffers with anti-depressant
drugs which alter serotonin levels
(SSRI)
However Kaye (2001) suggests
They are NOT effective until the AN
patient is in recovery – the individual’s
weight needs to have reached an
‘normal’ level
Also Dopamine ….. Kaye 2005
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Found over activity in Dopamine receptors
Over activity in dopamine receptors were found in the basal ganglia of
10 women recovering from AN compared to 12 healthy controls.
It is suggested this alters the way they interpret ‘rewards’. Good feelings
may not be associated with food for example. Again possible drug
therapies could be developed in the future if a causal link is established
Neurodevelopment
There is a possible connection
between premature birth and AN.
Lack of oxygen could be a factor
The child may lack adequate
nutrition
Double disadvantage 
Having an AN mother (genetic
transmission) AND
Inadequate nutrition in the womb
– Bulick (2005)
There is support for this explanation
of AN. (Favaro 2006)
Obstruction of blood supply in the
placenta, together with low birth
weight and eating difficulties was
associated with development of AN in
later life.
EVOLUTIONARY EXPLANATIONS OF
ANOREXIA NERVOSA
PSYCHOLOGICAL
and
NEUROCHEMICAL
EXPLANATIONS
FOCUS ON
ANOREXIA
NERVOSA AS A
DISORDER …
EVOLUTIONARY
EXPLANATIONS
ASSERT THAT AN
MAY HAVE BEEN
ADAPTIVE …
REPRODUCTIVE SUPPRESSION HYPOTHESIS
basic assumptions
# weight loss was a strategy for suppressing
reproductive capability (Surbey 1987)
# when food was in limited supply, pregnancy
would have been risky for the mother and survival
chances for the infant would have been reduced
# in the absence of contraceptives, weight loss
would prevent pregnancy at times when it would
be too risky
REPRODUCTIVE SUPPRESSION HYPOTHESIS
based on 2 ‘models’
the reproduction suppression model : because reproduction
is costly to females, a female facing conditions temporarily
unfavourable to reproduction can increase her lifetime
reproductive success by delaying reproduction until
conditions improve
the critical fat hypothesis : because a minimum amount of
body fat (17%) is needed before menstruation begins and
additional fat accumulation (22%) is needed to maintain
regular ovulation (Frisch, 1985; Frisch and Barbieri, 2002)
altering the trajectory of adolescent weight gain, or the loss of
five pounds or so, could have been an effective mechanism for
controlling sexual maturation and fertility in ancestral females
Adapted to Flee Hypothesis
• GUISINGER (2003)
• EEA >>Famine conditions >>> migration
required
• Food restriction, hyperactivity, denial of
hunger could be an adaptive mechanism
that prepares the individual to move to
find food
• ‘ancestral mechanisms’
PSEUDO-NUBILE-FEMALE HYPOTHESIS
AN is the result of intra-sexual selection
what is intra-sexual selection?
It is the process that results in only those
characteristics/behaviours that enhance chances of successful
same-sex competition for a mate remaining in the gene
pool
I.e. What makes you more attractive than another potential
mate
PSEUDO-NUBILE-FEMALE HYPOTHESIS
AN is the result of intra-sexual selection
how does INTRA-SEXUAL SELECTION lead to AN?
- in the ancestral environment, the female shape was a
generally reliable indicator of the female’s reproductive
history and hence her future reproductive potential
- the female nubile, ‘hour-glass’ shape is the product of
sexual selection and represents the most desirable visual
cue for males; in addition to the hour-glass appearance
the hallmark of the nubile shape is its relative thinness
compared to older females
PSEUDO-NUBILE-FEMALE HYPOTHESIS
AN is the result of intra-sexual selection
how does INTRA-SEXUAL SELECTION lead to AN?
- in the modern age, ‘mating behaviour’ is not necessarily
linked with reproduction (2nd marriages, etc); AND
female youth is no longer a pre-requisite for reproduction
(technology = older mothers)
- therefore progressively older females benefit from retaining
or recreating the nubile shape.
PSEUDO-NUBILE-FEMALE HYPOTHESIS
AN is the result of intra-sexual selection
how does INTRA-SEXUAL SELECTION lead to AN?
- it is argued that during the EEA most women of
reproductive age were either pregnant or lactating and
therefore temporarily infertile... therefore, it has been
suggested that, to avoid rearing another man’s offspring
men must have developed an aversion to even a slight
thickening of the waist (Ridley,1993).
- such aversion would be expected to be directed towards
novel females (i.e., a female who is not already the male’s
consort) and should be particularly relevant to the male’s
choice of a long term mate.
Other possible explanations
Psychodynamic explanation
How might Freud explain
eating disorders?
Psychodynamic explanation
Freud:
Evidence for Psychodynamic explanation
Hilda Bruch (1980)
Steiner et al (1991)
• Looked at origins of the illness in
childhood.
• Supported Bruch.
FOUND
• Results from poor parenting
• Observed adolescents
with anorexia
• Parents don’t cope with children’s
needs correctly
FOUND
E.g.
• Giving the child food when they are
anxious, as if that will solve the
problem.
• The parents were too
involved in the child’s
appearance, rather than
letting the child figure it
out on her own
• Anticipate their child’s
needs instead of letting
the child tell them when
they are hungry.
Evaluation on psychodynamic approach
Cognitive Explanation
Cognitive Explanation
Sufferers of anorexia nervosa often have a misperception of their body.
Faulty thinking
Errors in thinking
1) Thinking they are
overweight when
they are in fact
underweight.
2) Basing self worth on self
appearance.
3) Using eating as self
control.
Symptoms and signs
1) All or nothing – eating
one piece of chocolate
ruins everything
2) Overgeneralising –
thinking you’ll fail in life if
you can’t control eating
3)
Magnification/minimising
– weight loss isn’t serious
4) Magical thinking – life
will be complete when
I’m a size 4
 Dramatic weight loss over a
short period.
 Dieting despite being thin.
 Fixation on body image.
 Harshly criticising oneself.
 Feeling fat; despite being
thin.
 Denial that you are too thin.
 Strange food rituals.
 Preoccupation with food.
 Using diet pills.
 Compulsive exercising.
 BMI below 18.5/15
Evidence for the cognitive explanation
Fallon & Rozin (1985)
• Male & female participants
• Shown body silhouettes increasing in
size
• Told to rate their current body size,
ideal body size and body size the
opposite sex would find most
attractive
FOUND
• Men rated ‘current’&’ideal’ close
together. And ‘attractive’ as smaller.
WHEREAS
• Females rated ‘attractive’ body as
smaller than their ‘current’. And ‘ideal’
to be smaller than both.
MacKenzie et al
(1993)
•
Interviewed female eating
disorder patients & a control
group
• About body weight, shape &
ideals
• Then to compare their body to
other women's (who were the
same size)
FOUND
• Women saw themselves as
bigger
• Females chose ideal weight
smaller than control group
• Gave pp’s chocolate and a drink
and asked to re-estimate their
size.
• Control group chose no
different, other group chose
bigger
Evaluation of the cognitive approach
• Helps show what can help maintain an eating disorder, but not what causes them.
• Ethical issue = the explanation sometimes blames the sufferer.
• People who are clinically ‘normal’ too have irrational thoughts; what’s the difference?
• States the obvious – sufferers of anorexia see themselves as overweight.
• Women are generally more dissatisfied with their bodies than men, yet not all have eating
disorders.
Learning Theory
Behaviourist approach
• Classical conditioning
A learned association between
eating and anorexia
• Operant conditioning
Reinforcement of dieting
– ‘’you look amazing!!’’
• Social Learning Theory
Imitating desired role
models e.g. skinny models
Behaviourist approach
food is associated with putting on
weight and feeling anxious, and
out of control
Classical
conditioning
Not eating is associated with losing
weight and feelings of relief and
reduced anxiety
AN is a Learnt behaviour
Behaviourist approach
Positive Reinforcement - wow
you look great!
Operant conditioning
Negative reinforcement - I ate
too many calories. I feel terrible
- I must avoid eating so I don’t
have to feel this bad again
You look better, have
you put on a little bit of
weight?
OUCH!! (punishment)