Psychological Reasons Why Diet Drug Works

Main Category: Psychology / Psychiatry
Also Included In: Obesity / Weight Loss / Fitness
Article Date: 11 Sep 2009 - 3:00 PDT

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Psychologists are set to reveal the results of a study into obese people's behavioural responses to a prescription weight loss drug at the British Psychological Society's Division of Health Psychology annual conference today, 11th September 2009.

Amelia Hollywood and Jane Ogden from the University of Surrey investigated the behaviour of 572 individuals who had been prescribed the weight loss drug, orlistat (also known as Xenical). One of the most commonly prescribed obesity medications, orlistat acts on the gastrointestinal system by reducing the amount of fat absorbed into the body. This fat is instead eliminated in bowel movements - so if foods high in fat are eaten there are unpleasant consequences including liquid stool and anal leakage. It is thought that orlistat also deters unhealthy eating because of these unpleasant effects. 572 people taking orlistat who had registered on the Xenical support telephone line took part in the study.

Participants completed questionnaires detailing information on their weight, the side effects of the medication they had experienced and adherence to the medication at the start of their treatment and again six months into treatment. They were also asked about their motivation to start losing weight and their beliefs about the causes and solutions of obesity.

Preliminary findings presented at the conference suggest that after six months taking orlistat, on average participants' weight and BMI had significantly decreased, by 4.52kg and 1.72kg/m2 respectively. Analysis of the individuals who successfully lost weight while on orlistat showed that this decrease in BMI was predicted by a decrease in the amount of unhealthy food consumed and the belief that the unpleasant consequences of taking orlistat had made them change their behaviour.

Amelia Hollywood said: "Our findings support the idea that orlistat works not only on a physical level, but also psychologically - as it encourages people to see their diet as a cause of their weight problem. In addition, the side effects are so unpleasant that people avoid bad eating fatty foods and therefore lose weight.

"However, the way in which some people responded to orlistat was surprising. Some participants in this study reported that their eating behaviour became significantly unhealthier over the six month period. People also told us that they were not adhering to the medication as they should. It seemed that these people were taking orlistat as a lifestyle drug - choosing to take it when they were eating foods higher in fat to reduce any weight gain or not taking it when going on holiday or out for a meal as they didn't want to experience the consequences of eating fatty foods.

"However it also indicates that the drug educates people to understand which foods are fatty and will cause the unpleasant consequences so rather than change their eating behaviour some change when they decide to take the medication."

The British Psychological Society's Division of Health Psychology annual conference is taking place at Aston University, Birmingham from 9 - 11 September 2009.

Source
British Psychological Society

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