The eight-year weight loss findings from the Look AHEAD Study  reported in this issue of Obesity have important implications for treatment of overweight and obesity. As the largest and longest randomized controlled trial of a behavioral intervention for weight loss, the results from Look AHEAD provide vital information about the short- and long-term effects of an intensive lifestyle intervention for weight management. Over the course of eight years, participants in Look AHEAD's intensive lifestyle intervention achieved significantly larger mean reductions in body weight than those randomized to a diabetes support and education group. Moreover, at year 8, significantly greater percentages of lifestyle intervention participants attained weight reductions of 5% or greater and 10% or greater compared with those in the diabetes support and education condition. The ramifications of these findings with respect to lifestyle treatment of obesity are indeed notable.
The Look AHEAD results demonstrate that weight losses can be achieved and, for the most part, sustained via behavioral management of diet and physical activity. At year 1, the lifestyle program produced a mean body weight reduction of 8.5%. Over the next four years, a gradual regaining of weight was observed, followed by the maintenance of losses of approximately 4-5% in subsequent years. At year 8, the lifestyle program participants sustained on average more than half (55%) of their year 1 weight losses. Moreover, the majority succeeded in achieving reductions in body weight of 5% or more. Look AHEAD's findings stand in contrast to those of prior trials showing that participants regain the majority of lost weight within 3-5 years. The success of Look AHEAD is likely due to the intensive and comprehensive nature of the lifestyle intervention, and confidence in the study's findings is underscored by the trial's excellent rate of retention (i.e., more than 88% of the study's 5,145 participants completed the year 8 assessment).
The weight changes observed in Look AHEAD were accomplished in a diverse sample of participants. Thirty-seven percent were self-identified as members of ethnic or racial minority groups, and more than 40% were men. Prior trials have been less inclusive with respect to ethnic/racial and gender representation, and it has commonly been assumed that non-white participants achieve poorer outcomes in lifestyle programs. While non-Hispanic whites in Look AHEAD had larger year 1 weight losses, subsequent assessments at years 4 and 8 showed comparable weight reductions for the four ethnic/racial groups in the study (African American, Hispanic, American Indian/Other, and non-Hispanic white participants). The Look AHEAD findings also indicated that men and women had comparable weight loss outcomes at all assessment points. These results show that the lifestyle intervention produced long-term weight losses independent of the participant's race, ethnicity, or gender. However, older participants (those 66-76 years at baseline) had somewhat greater weight losses than younger ones (age groups: 45-55 and 56-65 years), particularly at year 8, but it is difficult to discern whether this difference was due to the effects of aging and disease progression or to greater adherence among older participants. Relatedly, it is unknown whether the patterns of long-term weight changes observed in Look AHEAD are generalizable to younger adults (ages 21-44 years) and to individuals who do not have diabetes.
The problem of poor maintenance of lost weight has been one of the greatest challenges associated with lifestyle interventions. The Look AHEAD findings demonstrate that a substantial degree of long-term weight loss is possible. However, the achievement of that outcome appears to require intensive, ongoing care, based on sound behavioral principles. It has long been recognized that the prescription of changes in diet and exercise, without clinical decision making based on behavioral theory and analysis, is unlikely to produce long-term changes in body weight. The lifestyle intervention in Look AHEAD included a comprehensive array of empirically supported behavioral treatment components, individually tailored through the use of problem-solving and “tool box” strategies, and delivered via structured programs of ongoing group and individual contacts.
Look AHEAD's intensive lifestyle program with its focus on the use of behavioral self-management strategies was partially successful in helping participants to negotiate the strong environmental and psychosocial factors that foster a regaining of lost weight. Indeed, participants in the lifestyle intervention reported greater use of weight-control strategies than those in the diabetes support and education group. At years 1, 4, and 8, lifestyle program participants indicated a higher frequency of exercise, periods of reduced caloric intake, regular self-weighing, and use of meal replacements, compared with those in the diabetes support and education condition. Furthermore, highly successful lifestyle participants (i.e., those who achieved and maintained weight reductions of 10% or more) reported greater use of these strategies than those individuals who lost 10% or more but subsequently regained it. These data may be subject to a reporting bias such that individuals who are more successful in losing weight may tend to overestimate their use of self-management strategies. However, it is more likely that greater use of weight-control strategies contributes to successful weight management and that lifestyle programs succeed by promoting key behaviors for weight management.
The magnitude of the net weight loss difference between the lifestyle intervention and the diabetes support and education group in Look AHEAD diminished over time, from a peak of 8.3% at year 1 to 2.6% at year 8. The clinical significance of the weight loss advantage favoring the lifestyle intervention is likely to be questioned by some, particularly in light of the trial's negative finding with regard to its cardiovascular endpoints . However, clinically meaningful benefits associated with the lifestyle intervention have been documented in earlier reports from Look AHEAD . Lifestyle participants were more likely to achieve reductions in sleep apnea and depression and to experience improvements in quality of life, physical functioning, and mobility. Moreover, lifestyle participants were less likely to be treated with insulin and more likely to achieve a partial remission of their diabetes.
The lessons learned from Look AHEAD are for the most part quite encouraging. The intensive lifestyle intervention helped overweight and obese individuals to lose substantial amounts of weight and to keep the majority of it off over the course of eight years. Comparable long-term weight changes were accomplished by men and women and by individuals from diverse ethnic and racial backgrounds. Furthermore, the changes in body weight were accompanied by clinically meaningful improvements in a variety of disease conditions. These positive findings are tempered by the finding that lifestyle participants experienced a regaining of weight despite ongoing care, and a vital question that remains to be addressed is whether the intensive lifestyle intervention delivered in the resource-rich environment of Look AHEAD can be adapted to produce comparable benefits in real world, clinical and community settings.