Characteristics of successful weight losers

Nutrition Research Newsletter, June, 2006

Close to 10 years have passed since the initial descriptive analyses of 784 successful weight losers who had enrolled in the National Weight Control Registry (NWCR). The NWCR is a registry of participants who have lost e" 13.6 kg (30 lb) and maintained the loss for e" 1 yr. The initial participants far exceeded the minimum criteria: participants lost an average of 30 kg and maintained the minimum 13.6 kg loss for an average of 5.5 yrs. Additional characteristics included eating a low-calorie (1360 kcal/d) diet, eating a low-fat (24% calories from fat) diet, engaging in a high level of physical activity (approximately 2786 kcal/week), frequent self-weighing, and eating regular meals, including breakfast.

As the Registry is now almost 10 years old, investigators were interested in re-examining the weight loss and maintenance behaviors of individuals entering the NWCR to determine whether the characteristics of successful weight losers have changed. Specifically, they investigated changes in the weight maintenance behaviors of Registry members. Furthermore, they examined the relationship between the characteristics of successful weight losers and subsequent 1-year weight changes.

Participants included 2123 women and 585 men who enrolled in the Registry in 1995, 1997, 1999, and 2003. Prospective participants were recruited through coverage of the NWCR provided by local and national media sources describing the Registry and its entry criteria. Participants provided information on their lifetime maximum weight, current weight, and approximate date at which they were at these weights.

All subjects completed a questionnaire requesting standard demographic information (age, ethnicity, education level, and marital status) and details about weight history (maximum lifetime weight, current weight, and duration of the required minimum 13.6 kg weight loss). Participants were also asked about what they were currently doing to maintain their weight loss. Dietary intake was assessed by using a scannable version of the Block FFQ. Frequency of breakfast consumption, number of daily meals, and frequency of fast food consumption were also evaluated. In order to assess current levels of physical activity, participants completed the Paffenbarger physical activity questionnaire, which asks for information about walking, stair climbing, and recreational activities engaged in during the past week.

One year following their initial entry into the Registry, participants were asked to again report their present weight and to complete assessments pertaining to their weight maintenance methods.

From 1995 to 2003, the daily percentage of calories from fat increased from 23.8% to 29.4%, saturated fat intake increased from 12.3 to 15.0 g/day, and calories from carbohydrate decreased from 56.0% to 49.3% (p < 0.0001). The proportion consuming <90 grams of carbohydrate (considered a low-carbohydrate diet) increased from 5.9% to 17.1% (p = 0.0001). Physical activity was elevated in 1995 (mean = 3316 kcal/week) but comparable in all other years (mean = 2620 kcal/week). Stepwise regression collapsing across cohorts indicated that weight regain over 1 year was related to higher levels of caloric intake, fast food consumption, and fat intake and lower levels of physical activity (p < 0.03).

While the macronutrient composition of the diet of NWCR participants has shifted in the past decade, only a minority consume a low-carbohydrate diet. Despite changes in the diet over time, the variables associated with long-term maintenance remained similar.

S. Phelan, H. Wyatt, J. Hill, et al. Are the eating and exercise habits of successful weight losers changing? Obesity; 14: 710- 716 (April, 2006) [Correspondence: Suzanne Phelan, Weight Control and Diabetes Research Center, 196 Richmond Street, Providence, RI 02906. E-mail: sphelan@lifespan.org]