Psychologists recently have gained new insights into the factors affecting the success of anti-obesity drugs.

Dr. Amelia Hollywood of Surrey University, UK, explains, “Weight-loss medication is widely prescribed, but with very mixed results. Many patients either do not lose weight or go on to regain any weight lost. We felt it was important to look at the experiences of these people who do not lose weight, or do not maintain the weight lost in the long term with this drug.”

Her team interviewed 10 women who were prescribed the weight-loss medication orlistat (Xenical). It acts on the gastrointestinal system and works by reducing fat absorption in the gut, which is eliminated in bowel movements.

The 10 women were chosen because they had put on weight over the 18 months since they started taking orlistat. These women saw their failure to lose weight as “an inevitable part of their identity,” and they had a “self-fulfilling belief that they would be perpetual dieters.”

In their interviews, the women blamed the mechanics of the drug, highlighted the barriers to weight loss, and talked about other weight-loss methods which previously had not worked.

“Their beliefs about themselves and about the difficulty of losing weight lay behind the failure of the anti-obesity drugs,” said Hollywood. She presented the study at the Annual Conference of the 2012 British Psychological Society’s Division of Health Psychology in Liverpool, UK.

At the conference she stated, “Our research suggests that prescribing this type of drug should be accompanied by information that reinforces the reality of sticking to the low-fat diet that is necessary to avoid the unpleasant consequences of the drug, such as anal leakage, and that these ‘side effects’ should not be attributed to the drug but to the individual’s eating behavior.

“Unless we get the psychology right and change people’s beliefs about themselves, their eating and the way the drug works, this medication is often going to produce disappointing results.”

Hollywood added, “We hope our research will encourage the doctors to prescribe this medication more wisely and to provide patients with more support while they are taking it.”

Weight Loss Success

The research team also carried out a study on the predictors of successful weight loss on orlistat, using 566 patients. All completed a questionnaire at the start and after six months concerning their weight, beliefs, and behaviors.

After six months, three-quarters of patients had lost some weight and the majority showed improvements in healthy eating. Many had also stopped taking orlistat and a large minority reported using flexibly in response to their dietary choices.

The patients who lost the most weight after six months had “a greater endorsement of a medical solution to obesity” at the start of treatment, meaning that those who have higher expectations of success for the drug went on to have greater success.

When the patients’ changes in beliefs and behavior over the course of taking orlistat were analyzed, results showed that those who lost the most weight showed a decrease in belief in a medical solution; a decrease in unhealthy eating; an increased belief in treatment control; and an increased belief that the side effects are both due to their eating behavior and just part of how the drug works.

“It would seem that taking orlistat may encourage patients to focus on their behavior rather than medical factors as solutions to obesity,” the team writes in the Journal of Obesity. If such changes in beliefs occur alongside improvements in diet, a patient’s weight loss is greater.

“This indicates that the side effects of orlistat, while being unpleasant and a deterrent for some users, may help educate others towards a more behavioral focus on their weight problem,” the team writes.

They conclude that, although research indicates that orlistat can promote weight loss, “there remain problems with adherence and much variability in patient outcomes. Our results indicate that changes in beliefs and behavior occurring throughout the course of taking orlistat are the best predictors of outcomes, rather than baseline variables.”

“Further, the results indicate that those patients who show a shift away from a medical model of their problem towards a focus on their own behavior and show improvements in their diet, lose more weight.”

The researchers suggest that these results could be useful for patient management. The unpleasant side effects caused by orlistat may lead to nonadherence, but “rather than conceptualizing such side effects as unfortunate, they may be the very ‘active’ ingredients necessary to bring about change in patients’ behavior.”

“When prescribing orlistat, clinicians should encourage patients to focus and learn from the side effects in terms of what they are eating. Such an emphasis may encourage patients to see these consequences of the drug as an education, thus enabling them to take more ownership of their weight problem, in turn facilitating and promoting changes in eating behavior.”

Reference

Hollywood, A. and Ogden, J. Taking Orlistat: Predicting Weight Loss over 6 Months. Journal of Obesity, November 2011, doi:10.1155/2011/806896

Weight-Loss Beliefs Jeopardize Anti-Obesity Drugs