LOSING WEIGHT AND KEEPING IT OFF is a tough business—no one succeeds without really trying. But some long-held beliefs about the difficulties of maintaining weight loss are changing. As a result, experts are developing a more complete picture of weight loss maintenance and a more hopeful message for millions who are overweight or obese. Experts who presented data on maintaining weight loss during the Endocrine Society’s annual meeting in Toronto last month said the proportion of overweight individuals who succeed at long-term weight loss—losing at least 10% of body weight and keeping the weight off for 1 year—is higher than many might expect, about 20% (McGuire MT et al. Int J Obes Relat Metab Disord. 1999;23[12]:1314-1319). An even more optimistic outlook appears in a recent study. Researchers from the Centers for Disease Control and Prevention report that nearly 60% of 1310 individuals in the National Health and Nutrition Examination Survey who lost 10% of body weight maintained 95% of the loss for 1 year (Weiss EC et al. Am J Prev Med. 2007;33[1]: 34-40). “Weight maintenance following weight loss is doable,” lead author Edward C. Weiss, MD, MPH, said in a statement. Holly Wyatt, MD, an associate professor at the University of Colorado Health Sciences Center, Denver, agreed. “A lot of people say you can’t succeed at maintaining weight loss long-term,” she noted during a press briefing at the meeting in Toronto. “We do have some data now that say that’s not true.” METABOLIC ROLE Wyatt said the theory that weight loss lowers the resting metabolic rate (RMR), which in turn pushes the body to regain lost pounds, is not a catchall explanation for weight regain. She examined the existing medical literature and found several studies that contradict the theory. Among them is a study of 24 overweight, postmenopausal women who, after 4 phases of weight loss and weight maintenance, lost a mean of 12.9 kg (Weinsier RL et al. Am J Clin Nutr. 2000; 72[3]:1088-1094). After measuring changes in the women’s RMR and thyroid hormone levels compared with 24 control participants, researchers from the University of Alabama School of Medicine, Birmingham, and the Mayo Clinic, in Rochester, Minn, reported a temporary decline in RMR and thyroid hormones in the study participants. However, measures of both returned to baseline after the women stopped losing weight. The RMR in the women who had lost weight was not significantly different than in controls, and women with lower RMRs were not more likely than those with higher rates to regain more weight over the next 4 years. “The idea that absolutely, your body is fighting you, I don’t think really holds out in the literature,” said Wyatt. “Other things like our environment or other behaviors may overpower [metabolic] change.”