Eating behaviour

Question 1

Studies supporting genetic explanation for obesity

Answer 1

• Nan meta-analysis 12 studies, heritability of BMI was high between 60-80%
• Frayling found people with 2 copies of FTO gene had a 70% increased risk of obesity compared to only 30% in those with one copy

Question 2

Studies supporting neural explanation for obesity

Answer 2

• Wang found obese individuals had significantly fewer dopamine receptors than ‘normal weight’ controls. Concluded that overeating is an attempt to activate reward centres by increasing dopamine
• Ohia found that mice with no functioning serotonin receptors develop late on-set obesity

Question 3

Studies supporting the psychological explanation of cognitive theory of AN

Answer 3

• Garner compared 160 anorexics to 140 non-anorexics and found the anorexics were more likely to overestimate their bodyweight/size

Question 4

What are the 5 features of an anorexic family?

Answer 4

• enmeshment
• rigidity
• autonomy and control
• overprotectiveness
• conflict avoidance

Question 5

Studies supporting the role of learning in food preferences

Answer 5

• Birch found mothers’ eating behaviours and attitudes towards child-feeding practices influence children’s food preferences and eating behaviour when they move onto solid food
• Harper and Sanders found that observing the eating practices of mothers was more influential than watching strangers
• Study found that food mothers ate during pregnancy and whilst breastfeeding affected the child’s early experience of food flavours and shaped their food preferences when older

Question 6

Role of neural and hormonal mechanisms studies

Answer 6

• Lashley: rats trained to run a maze to gain food. Different parts of a rat’s brain were lesioned to control eating behaviour. Lesions to rats LH stopped eating whilst lesions to the VMH caused rats to eat excessively.
• Stellar found that stimulating the VMH increased eating and had the opposite effect for the LH.
• some studies have shown that rats can reach satiety even when the VMH is lesioned
• Wren found injecting ghrelin caused a short term increase in the amount eaten.
• Baicey found that leptin binds to NPY neurons which signals to the hypothalamus to produce a feeling of satiety.

Question 7

Success/failure of dieting studies

Answer 7

• Lohman followed dieters through first 4 months of 2 year programme. 1 in 5 dropped out. Unsuccessful dieters had greater expectations about weight loss and higher body dissatisfaction: dieting isn’t successful for losing weight
• Yager found that disinhibited eaters who failed dieting turned to substance abuse.
• Lowe found an average of 72% of weight watchers members maintained a body weight loss of 5% indicating social support motivates weight loss and its maintenance.