Mulrow, Cynthia D.Helping an obese patient make informed choices. (Clinical Review) British Medical Journal v317, n7153 (July 25, 1998): 266 (2 pages).Copyright 1998 British Medical Association (U.K.)

Not long ago, a patient, whom I will call Mrs. Bariatrico, asked me to prescribe a diet pill for her. Mrs. Bariatrico is a middle class woman aged 48 years. She is 1.6m tall and weighs 77.2 kg. Her body mass index is 30.2 and her waist to hip ratio is 1.0 Mrs. Bariatrico is healthy and does not smoke. She told me she plans to enroll in a commercial diet programme and believes her ability to change her lifestyle is good? Her main concern is cosmetic--she values "looking good" and considers weight loss an important outcome.

As her primary care provider, I had several concerns. I knew the health insurance system that serves Mrs. Bariatrico has no formal weight loss programmes, and the cost of appetite suppressing drugs in not reimbursed. I had some doubts about my own ability to manage obesity and asked the following questions:

Expected benefits and hazards

Randomised trials confirm several physiological benefits--including reductions in blood pressure and glucose and lipid concentrations--when weight is reduced by 10-15%. [2] Trials are neither large enough nor long enough to identify survival benefits.One observational study that lasted 12 years showed that an intentional weight loss of 0.5-9.0 kg in overweight women with disorders related to obesity was associated with a 20% reduction in all cause mortality (relative risk = 0.80; 0.68 to 0.94). [6] Potential hazards of weight loss include increased risks of gallstones during rapid weight loss and loss of bone density.[2]

Treatment options

A comprehensive systematic review from the Centre for Reviews and Dissemination evaluates treatment options appropriate for Mrs. Bariatrico.[7] These include diet, exercise, and appetite suppressing drugs.A recent book describes many complementary therapies, including herbal remedies and chromium, but none have been adequately evaluated in controlled trials?

Diet and exercise

Randomised controlled trials show that diets allowing an intake of 1200 kcal/day coupled with behavior modification result in an approximate weight loss of 8.5 kg at 20 weeks.[9] Providing patients with food and meal plans, focusing on restricting fat as well as calories, and encouraging daily self monitoring of weight may be particularly effective strategies.[7] Very low calorie diets of less than 800 kcal/day result in a weight loss of approximately 20 kg at 12 to 16 weeks. One half to two thirds of the weight loss is maintained at one year. [9] Adding regular aerobic exercise results in minimal additional weight loss (approximately 2.5 kg after six months) and limits the amount of weight regained.[10] Resistance exercise has little effect on weight but increases the lean body mass.[10]

Appetite suppressants

Double blind randomised trials of longer than six months' duration show that antidepressant serotenergic agents such as fluoxetine are not effective weight loss treatments.[7.11] Other serotonergic agents, dexfenfluramine and fenfluramine (a racemic mixture of D-fenfluramine and L-fenfluramine), are effective when combined with diet. [7.11] Five trials, in which 1029 patients participated, showed that the weight loss with dexfenfluramine was 2.5 to 8.7 kg greater than with placebo at six months; two trials showed losses of 2.6 and 4.2 kg at 12 months.[11] The combination of fenfluramine and phentermine (colloquially known as fen-phen) resulted in a loss of 9.7 kg after six months compared with placebo. The two drug are sibutramine (serotonin and noradrenergic reuptake inhibitor) and orlistat (a fat absorption inhibitor). In one multicentre randomised trial, sibutramine showed a 2.8 kg loss compared with placebo at 12 months.[7] In a preliminary report from one centre of a multicentre trial comparing orlistat with placebo, weight reduction with orlistat was 3.1 kg more than with placebo at six months.[12] Trial data beyond 12 months of active treatment are not available for either of the two agents, and effects on mortality are not known.

Adverse effects that occur in more than 10% of patients taking dexfenfluramine include tiredness, diarrhea, and dry mouth. Use of appetite suppressants (mostly dexfenfluramine) for more than three months is associated with pulmonary hypertension.[13] The risk is estimated at 23-46 cases per million per year or one in 22,000-44,000 patients taking appetite suppressing drugs. Highly publicized case series describe unusual heart valve deterioration in 60 otherwise healthy women taking newer agents.[1415] Most were taking the combination of fenfluramine and phentermine, but six were taking either fenfluramine or dexfenfluramine alone. [14 15] In addition, a case series of 291 asymptomatic people taking these drugs showed that 92 had evidence of valvular disease, primarily aortic regurgitation.[16] This information prompted manufacturers to withdraw dexfenfluramine and fenfluramine from the market in September 1997.

The informed decision

I gave Mrs. Bariatrico feedback on the health risks of obesity, listed the treatment options, and advised her about the expected effects. She viewed the health risks of obesity as relatively minor and reiterated her primary value of losing weight so she would "look and feel good." She was surprised that the weight loss expected from diet pills was not greater and worried about possible serious adverse heart effects. She was determined to try a low fat, low calorie diet and daily exercise. I praised her willing ness to tackle difficult lifestyle changes. On her way out the door, she turned, smiled at me, and requested a prescription for phentermine--one of the few remaining appetite suppressants available on the market

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