It almost seems that a million-and-one books are published everyday touting the secret to rapid and sustained weight loss. But, how many of these diet schemes have been verified to produce the results they advertise? In the latest JAMA (Journal of the American Medical Association) issue, a group of academic centers involved in the Weight Loss Maintenance (WLM) initiative published their results from a three-year study comparing strategies for sustaining weight loss. The project is sponsored by the National Heart, Lung, and Blood Institute (NHLBI), and includes four clinical centers: Duke University, Johns Hopkins University, Pennington Biomedical Research Center, and the Kaiser Permanente Center for Health Research.

The design of the WLM clinical trial involves two phases. Phase 1 comprises a 6-month period where all participants undergo similar intervention to obtain weight loss. Working closely with a trained interventionist, the group strives to achieve a weekly weight loss goal of 1-2 pounds per week through a combination of strategies, such as caloric reduction, dietary modification, and increased physical activity. After having lost weight in phase 1, participants in the 30-month phase 2 trial are randomly divided into three groups, each with a different level of intervention to encourage maintenance of weight loss: 1) minimal intervention; 2) technology-based intervention, with use of an interactive website which sets personal goals, action plans, and provides an online support community; and 3) personal-contact intervention, involving monthly contact with a weight-loss interventionist.

Inclusion criteria for phase 1 includes a BMI (body mass index) in the overweight to obese range; history of hypertension, dyslipidemia, or both; and no active cardiovascular disease, diabetes, or conditions that would otherwise prevent adherence to the research protocol. To qualify for phase 2, the participant would have had to lose at least 4 kg (8.8 pounds) by the end of phase 1. Consequently, the initial study population of 1685 individuals who underwent phase 1 diminished to 1032 by the start of phase 2. The remaining participants reported a mean weight loss of 8.5 kg (18.7 pounds) and average decrease in caloric intake by 325 kcal per day.

Upon completion of the study, the three phase 2 groups had experienced similar non-significant, increases in caloric intake. Activity levels achieved during phase 1 had declined to pre-study levels by the end of follow-up. This finding supports the cliché that new habits are hard to form and old habits are hard to break. Despite similar changes among the three intervention groups in caloric intake and exercise regimen, the cumulative effect of these changes within each group resulted in significant differences in weight outcome. The self-motivation / minimal intervention group had a weight gain of 5.5 kg (12.1 lb) from phase 1; the technology-based group gained 5.2 kg (11.4 lb); and, the personal-contact group gained the least at 4.0 kg (8.8 lb).

Although the self-motivation and technology-based groups experienced marginal weight differences at the end, the differences in weight gain were larger earlier in phase 2. At 18 months, the technology-based group had gained 1.1 kg (2.4 lb) less than its self-motivation counterpart. This gap progressively closed over time. By 24 months, the difference was 0.9 kg (2.0 lb); it was 0.3 kg (0.7 lb) by the end of the study.

The authors conclude that “an initial 6-month behavioral weight loss program maintained weight below their entry level after 30 additional months. Monthly brief personal-contact sessions provided modest benefit in sustaining weight loss, whereas an Internet-based intervention provided early but transient benefit“.

While monthly contact with an interventionist proves beneficial, there are associated costs to seeking continual consultation with an expert. Even the personal gym trainer is not free. On the other hand, a cost-analysis may reveal that the health benefits from sustained weight loss would lead to a net reduction in health care spending. Treating obesity-related co-morbidities are far more expensive than simple preventive measures. It would be interesting to study the effect of frequency (i.e., weekly, monthly, bimonthly) meeting with an interventionist on weight gain. If there is no proven difference between meeting monthly–as was used in the WLM trial–or every 2-3 months, then a primary care physician could potentially fulfill the role of the interventionist. The next BIG question would then be, “would MediCare reimburse this service?”

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• Source:
• Svetkey LP, Stevens VJ, Phillip JP, et al. Comparison of strategies for sustaining weight loss: the weight loss maintenance randomized controlled trial. JAMA 2008;299:1139-48.