Review: Most obesity treatment methods are ineffective over the long term
ACP J Club. 1999 July-Aug;131:20. doi:10.7326/ACPJC-1999-131-1-020
Douketis JD, Feightner JW, Attia J, Feldman WF, with the Canadian Task Force on Preventive Health Care. Periodic health examination, 1999 update: 1. Detection, prevention and treatment of obesity. CMAJ. 1999 Feb 23;160:513-25.
What is the long-term effectiveness of methods to prevent and treat obesity?
English-language, published studies were identified with MEDLINE (1966 to April 1998) by using the terms obesity, body mass index, diet therapy, drug therapy, prevention and control, surgery, and therapy. Bibliographies of review articles and Current Contents listings were searched.
Randomized controlled trials (RCTs) or prospective cohort studies were selected if they investigated the prevention or treatment of obesity with dietary, pharmacologic, surgical, or dietary counseling and behavioral methods; had ≥ 2 years of follow-up; provided weight loss outcome data; and included ≥ 50 patients. Studies were excluded if there was nonconsecutive selection of patients, no report of patients lost to follow-up, or the interventions were unsafe.
Data were extracted on methodologic quality, patient and study characteristics, and weight loss outcomes.
Of 813 studies identified, 39 met the inclusion criteria. 3 studies of obesity prevention were community-based cohorts comparing a group exposed to health promotion programs with a control group; no differences in weight existed for follow-up durations of 3 to 7 years. There were 36 studies of obesity treatment. 14 studies (8 RCTs and 6 cohorts) examined dietary therapy alone or with other weight-reduction methods. The RCTs showed that supervised dietary therapy was most effective for short-term weight loss (mean losses 2 to 6 kg, mean follow-up 2 to 7 y). 8 anorectic drug studies (all RCTs) examined fluoxetine, fenfluramine, dexfenfluramine, phentermine, and mazindol. 7 of these studies (1- to 2-y follow-up) showed that anorectic drugs plus dietary therapy reduced weight during the first 12 to 24 weeks. 5 surgical studies (4 RCTs and 1 cohort) showed that surgical therapy generally reduced weight more than dietary or drug therapy (mean weight loss 27.6 to 45.5 kg, 3 to 6 mo after surgery, largely sustained during 2- to 5-y follow-up). 9 dietary counseling and behavioral therapy studies (5 RCTs and 4 cohorts) reported mean weight losses between 1 and 5 kg for 3 to 5 years of follow-up. Generally, weight loss occurred during the first 6 to 12 months of therapy with subsequent weight regain. 2 RCTs showed a mean weight loss of 4.5 kg, which was sustained over 4 years of follow-up.
Insufficient data are available to evaluate the effectiveness of obesity prevention methods. Most obesity treatment methods, except surgical and some dietary and behavioral treatment inter-ventions, are ineffective over the long term. Pharmacologic plus dietary therapy is initially more effective than diet alone, but data are insufficient to evaluate long-term effectiveness.
Source of funding: Provincial and Territorial Ministries of Health, and Health Canada.
For correspondence: Dr. J.D. Douketis, St. Joseph's Hospital, Room F-513, 50 Charlton Avenue East, Hamilton, Ontario L8N 4A6, Canada. FAX 905-521-6068; e-mail email@example.com.
A major conclusion of this review by Douketis and colleagues is not surprising: Insufficient evidence exists to make recommendations about most weight reduction methods for overweight individuals. For obese patients with comorbid conditions, such as type 2 diabetes mellitus and hypertension, the Canadian Task Force on Preventive Health Care recommends weight reduction therapy because good evidence exists that even short-term weight loss can reduce symptoms and medication requirements. Although this approach is reasonable, it seems less than ideal to treat only patients who already have a medical complication of obesity. Clinicians are accustomed, in the absence of conclusive data, to rely on clinical experience when making treatment recommendations. For obesity, it is important to consider evidence as well as to use clinical judgment. Many patients now turn to less well-studied or less safe methods of achieving weight reduction without a clinician's guidance.
This careful review showed that a combination of treatment regimens (diet, exercise, and behavior modification or pharmacologic and dietary therapy) were more likely to be effective, both in the short- and the long-term, than a single-regimen approach or no intervention. Because no truly safe and effective treatment exists for weight reduction, new agents are emerging and treatments are being improved. For clinicians to withhold treatment advice until an acceptable level of evidence for obesity management is available is, perhaps, a disservice. Efforts to show the long-term health benefits of weight loss are in progress with the National Institutes of Health's Study of Health Outcomes of Weight Loss (SHOW) trial. While weight reduction therapy is being more carefully tested and refined, in my view most clinicians should continue to offer encouragement and guidance to patients who might benefit from weight loss.
Lawrence J. Cheskin, MD
Johns Hopkins Bayview Medical CenterBaltimore, Maryland, USA