Saturday, October 3, 2009
THE NATIONAL WEIGHT CONTROL REGISTRY
Although it is often stated that no one ever succeeds in weight loss, we all know some people who have achieved this feat. In an effort to learn more about those individuals who have been successful at long-term weight loss, Wing and Hill (10) established the National Weight Control Registry in 1994. This registry is a self-selected population of more than 4000 individuals who are age 18 or older and have lost at least 13.6 kg (30 lb) and kept it off at least 1 y. Registry members are recruited primarily through newspaper and magazine articles. When individuals enroll in the registry, they are asked to complete a battery of questionnaires detailing how they originally lost the weight and how they now maintain this weight loss. They are subsequently followed annually to determine changes in their weight and their weightrelated behaviors.
The demographic characteristics of registry members are as follows: 77% are women, 82% are college educated, 95% are Caucasian, and 64% are married. The average age at entry to the
registry is 46.8 y. About one-half of registry members report having been overweight as a child, and almost 75% have one or two parents who are obese.
Participants self-report their current weight and their maximum weight. Previous studies suggest that such self-reported weights are fairly accurate (slightly underestimating actual weight) (11, 12). In the NWCR, participants are asked to identify a physician or weight loss counselorwhocan provide verification of the weight data. When, in a subgroup of participants, the
information provided by participants was compared with that given by the professional, the self-report information was found to be very accurate.
Participants in the registry report having lost an average of 33 kg and have maintained the minimum weight loss (13.6 kg) for an average of 5.7 y. Thirteen percent have maintained this minimum weight loss for more than 10 y. The participants have reduced from a BMI of 36.7 kg/m2 at their maximum to 25.1 kg/m2 currently. Thus, by any criterion, these individuals are clearly extremely successful.
Previously, we reported information about the way in which registry participants lost their weight (10); interestingly, about one-half (55.4%) reported receiving some type of help with
weight loss (commercial program, physician, nutritionist), whereas the others (44.6%) reported losing the weight entirely on their own. Eighty-nine percent reported using both diet and physical activity for weight loss; only 10% reported using diet only,and 1% reported using exercise only for their weight loss. The most common dietary strategies for weight loss were to restrict certain foods (87.6%), limit quantities (44%), and count calories (43%). Approximately 25% counted fat grams, 20% used liquid formula, and 22% used an exchange system diet. Thus, there is variability in how the weight loss was achieved (except that it is almost always by diet plus physical activity).
The earliest publication regarding the registry documented the behaviors that the members (n = 784) were using to maintain their weight loss (10). Three strategies were reported very consistently: consuming a low-calorie, low-fat diet, doing high levels of physical activity, and weighing themselves frequently. Recently, a fourth behavior was identified: consuming breakfast
daily (13). Each of these behaviors is described below. Registry members reported eating 1381 kcal/d, with 24% of calories from fat. In interpreting their data, it is important to recognize that55% of registry members report that they are still trying to lose weight and to consider that dietary intake is typically underestimated by 20–30%. Thus, registry members are probably eating closer to 1800 kcal/d. However, even with this adjustment, it is apparent that registry members maintain their weight loss by continuing to eat a low-calorie, low-fat diet.
More recently, we have examined other aspects of their diet. Of particular interest is the fact that 78% of registry members report eating breakfast every day of the week (13). Only 4%
report never eating breakfast. The typical breakfast is cereal and fruit. Registry members also report consuming 2.5 meals/wk in restaurants and 0.74 meals/wk in fast food establishments.
Another characteristic of NWCR members is high levels of physical activity. Women in the registry reported expending an average of 2545 kcal/wk in physical activity, and men report an
average of 3293 kcal/wk (10). These levels of activity would represent =1 h/d of moderate-intensity activity, such as brisk walking. The most common activity is walking, reported by 76%
of the participants. Approximately 20% report weight lifting, 20% report cycling, and 18% report aerobics.
Registry members also reported frequent monitoring of their weight (10). More than 44% report weighing themselves at least once a day, and 31% report weighing themselves at least once a
week. This frequent monitoring of weight would allow these individuals to catch small weight gains and hopefully initiate corrective behavior changes.
The vigilance regarding body weight can be seen as one aspect of the more general construct of cognitive restraint (ie, the degree of conscious control exerted over eating behaviors). Registry
members are asked to complete the Three Factor Eating Inventory (14), which includes a measure of cognitive restraint. Registry members scored high on this measure (mean of 7.1), with levels similar to those seen in patients who have recently completed a treatment program for obesity, although not as high as eating-disordered patients. These findings suggest that successful weight loss maintainers continue to act like recently successful weight losers for many years after their weight loss.
