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Eating behaviour questions:
1. Discuss explanations for one eating disorder (psychological, neural and evolutionary)
Obesity is classed as an eating disorder in the DSM handbook. One explanation for obesity is the
psychological explanation which believes that the disorder is due to faulty thinking and cognitions.
This theory suggests that obesity can be caused in many different ways. One of these ways is
emotional and restraint eating. This theory believes that obesity is caused by overeating due to
being over emotional and thus self-medicating by eating. Herman and Mack found that emotional
arousal decreases eating restraint. Heatherton also supports this theory as he found that many
emotional eaters overeat to escape emotional pain. Specker further supports emotional eating as a
cause for obesity as he found much higher levels of depression and anxiety in obese patients. This
theory also follows on from Herman et al's restraint theory which suggests that restraining your
food intake actually causes over eating and consequently obesity. The second psychological
explanation for obesity is binge eating disorder. To be classified as having this disorder, the patient
must experience a lack of control whilst eating twice a week. It has been found that 1-3% of the
population have this disorder, with 30% of obese people claiming of this disorder. Davey found a link
between binge eating disorder and depression levels and low self-esteem. The last psychological
explanation is food addiction. This theory suggests that obese people suffer from a craving to
carbohydrates. Wardle stated this addiction is maintained via negative reinforcement but he also
found that obese people do not consume more carbohydrates than non-obese people. Morrison
also disputed this and said that taste was the primary factor with food.
Genetics play a large part in the predisposition of obesity. To study concordance rates of obesity,
twin studies are used. Using twin studies show us whether there is a relationship between twins, and
thus making a conclusion that genetics are involved. Gottesman looked at 34 monozygotic twins and
studied their body fat. The twins who were reared apart had a 61% concordance rate whereas
those who were reared together had a 75% concordance rate. These results show that there is a
genetic relationship, but due to the results being different between the two groups suggests that
there must be some other external factor involved. This can be explained by the social learning
theory. This theory suggests that behaviours happen due to observation and imitation, thus a
secondary explanation for the twin's concordance rate not being 100% (and therefore 100%
genetically based) is due to observing other family or peers and imitating their behaviours.
Bouchard conducted another study to see whether there is a genetic relationship between twins
and obesity. He found that when overfeeding twins there was a 3x larger similarity within twins that
between twins. Lastly Stunkard looked at the relationship between adoptees and their adoptive
and biological parents. Using a sample of 540 adoptees he found a strong correlation between the
biological parents and the adoptees BMI.
One issue with genetics and obesity is genetic engineering. If a specific gene was found to
predispose or cause obesity genetic engineering may begin to take place, and thus decreasing the
variation of the population by lowering the allele frequency.
The biological approach sides with the nature side of the nature versus nurture debate. The nature
side debates that behaviours are predisposed and that there is no free will as to choosing whether
or not this behaviour occurs thus making the theory deterministic. The nurture side of the debate is
supported by the behaviourist approach and thus the social learning theory. This is a counter
explanation to the biological or psychological approaches of explaining obesity.
Lastly there has been evidence to support the role of chemicals aiding obesity. Zhang conducted a
study using mice that had the ob/ob gene. This gene stopped leptin production. Leptin is a chemical
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These mice put on weight rapidly, and when injected with leptin, they
began to lose weight.
Following on from this, the evolutionary approach believes that these genes aid certain behaviour for
an adaptive reason. The evolutionary theory suggests that our behaviours have evolved from
hunter-gatherer times for a survival advantage. One reason for fat storage in evolutionary terms is in
the EEA they did not know when they would next eat and thus would biologically store their food.…read more
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This could be due to the fact black people have larger body shapes and therefore are trying to
achieve something that is not possible. On the other hand, it has been shown that bulimia is more
common in Asian girls. This could be because food in many Asian cultures is given as gifts and many
social gatherings compose of big meals. With the social side of trying to be thin this could be the way
in which many Asian girls try and bridge the gap.…read more
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This leads onto the nature nurture debate. The social
learning theory supports the nurture side of the debate whereas, the biological approach, such as
genetics, supports the nature side of the debate, believing that our genetics are what predispose us
to either being a successful dieter or a non-successful dieter.
The role of denial plays a huge part in dieting. Many dieters will try not to think about eating, yet will
find themselves over eating. Wegner et al conducted the `white bear' experiment.…read more
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VMH. Unfortunately there has been very few studies that replicate the same findings, and thus
decrease the validity of the study.
There is evidence to suggest the amygdala plays a part in the control of eating behaviour. Rolls and
Rolls found that when removing the amygdala from some animals the animal will eat anything and
everything. Intact amygdalas cause people only to eat palatable and familiar foods. If theinferior
frontal cortex is damaged this causes a lack of smell of food.…read more
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Not every food preference is beneficial in modern day, thus the adaption has not aided survival. The
high calorie diets are not welcomed in modern society due to the increased heart disease and
diabetes, thus these evolved genes are not advantageous to us.
Another evolutionary food preference is taste aversion. Taste aversion has been evolutionary
beneficial due to many poisonous foods with strong or bitter tastes.…read more