Saturday, October 3, 2009
ABSTRACT
There is a general perception that almost no one succeeds in longterm maintenance of weight loss. However, research has shown that = 20% of overweight individuals are successful at long-term weight loss when defined as losing at least 10% of initial body weight and maintaining the loss for at least 1 y. The National Weight Control Registry provides information about the strategies used by successful weight loss maintainers to achieve and maintain long-term
weight loss. National Weight Control Registry members have lost an average of 33 kg and maintained the loss for more than 5 y. To maintain their weight loss, members report engaging in high levels of physical activity (=1 h/d), eating a low-calorie, low-fat diet, eating breakfast regularly, self-monitoring weight, and maintaining a consistent eating pattern across weekdays and weekends.
Moreover, weight loss maintenance may get easier over time; after individuals
have successfully maintained their weight loss for 2–5 y, the chance of longer-term success greatly increases. Continued adherence to diet and exercise strategies, low levels of depression and disinhibition, and medical triggers for weight loss are also associated with long-term success. National Weight Control Registry members provide evidence that long-term weight loss maintenance is possible and help identify the specific approaches associated with long-term
success.
SUCCESSFUL WEIGHT LOSS MAINTENANCE
The perception of the general public is that no one ever succeeds at long-term weight loss. This belief stems from Stunkard and McLaren-Hume’s 1959 study of 100 obese individuals, which indicated that, 2 y after treatment, only 2% maintained a weight loss of 9.1 kg (20 lb) or more (1). More recently, a New England Journal of Medicine editorial titled Losing Weight: An Ill-Fated New Year’s Resolution (2) echoed the same pessimistic message.
The purpose of this paper is to review the data on the prevalence of successful weight loss maintenance and then present some of the major findings from the National Weight Control
Registry (NWCR), a database of more than 4000 individuals who have indeed been successful at long-term weight loss maintenance.
DEFINING “SUCCESSFUL WEIGHT LOSS MAINTENANCE”
Wing and Hill (3) proposed that successful weight loss maintainers be defined as “individuals who have intentionally lost at least 10% of their body weight and kept it off at least one year.”
Several aspects of this definition should be noted. First, the definition requires that the weight loss be intentional. Several recent studies indicate that unintentional weight loss occurs quite
frequently and may have different causes and consequences than intentional weight loss (4, 5). Thus, it is important to include intentionality in the definition.
The 10% criterion was suggested
because weight losses of this magnitude can produce substantial improvements in risk factors for diabetes and heart disease. Although a 10% weight loss may not return an obese to a non-obese
state, the health impact of a 10% weight loss is well documented (6). Finally, the 1-y duration criterion was proposed in keeping with the Institute of Medicine criteria (7). Clearly, the most
successful individuals have maintained their weight loss longer than 1 y, but selecting this criterion may stimulate research on the factors that enable individuals who have maintained their weight loss for 1 y to maintain it through longer intervals.
PREVALENCE OF SUCCESSFUL WEIGHT LOSS MAINTENANCE
There are very few studies that have used this definition to estimate the prevalence of successful weight loss maintenance. McGuire et al (8) reported results of a random digit dialing survey
of 500 adults, 228 ofwhomwere overweight or obese [body mass index (BMI)>= 27 kg/m2] at their maximum nonpregnant weight. Of these 228, 47 (20.6%) met the criteria for successful weight loss maintenance: they had intentionally lost at least 10% of their body weight and maintained it for at least 1 y. On average, these 47 individuals had lost 20.7 +- 14.4 kg (45.5 lb; 19.5 +- 10.6% from maximum weight) and kept it off for 7.2 +- 8.5 y; 28 of the 47 had reduced to normal weight (BMI < 27 kg/m2).
Survey data such as these have the perspective of a person’s entire lifetime and thus may include many weight loss attempts, some which were successful and some unsuccessful. It is more typical to assess “success” during one specific weight loss bout. In standard behavioral weight loss programs, participants lose an average of 7–10% (7–10 kg) of their body weight at the end of the initial 6-mo treatment program and then maintain a weight loss of =5–6 kg (5–6%) at 1-y follow-up. Only a few studies have followed participants for longer intervals; in these studies, = 3– 20% maintain a weight loss of 5 kg or more at 5 y. In the Diabetes Prevention Program (9), =1000 overweight individuals with impaired glucose tolerance were randomly assigned to an intensive lifestyle intervention. The average weight loss of these participants was 7 kg (7%) at 6 mo; after 1 y, participants maintained a weight loss of =6 kg (6%), and, at 3 y, they maintained a weight loss of =4 kg (4%). At the end of the study (follow-up ranging from 1.8 to 4.6 y; mean, 2.8 y), 37% maintained a weight loss of 7% or more.
Thus, although the data are limited and the definitions varied across studies, it appears that =20% of overweight individuals are successful weight losers.
