Weiss et al. (2007) – weight regain
The skills necessary to prevent the backslide of weight regain are elusive and hard to pinpoint. Patients treated by lifestyle modifications generally regain 30% to 35% of their lost weight in the year after treatment and will regain the majority, if not all of the weight lost, within five years. Weight regain has been associated with fast food consumption, higher television viewing, and lower levels of physical activity. The objectives of this study were to determine the prevalence and predictors of weight regain in adults in the United States who had experienced substantial weight loss.
Weight regain is both frustrating and dangerous. Once weight regain occurs, re-losing weight is challenging and unlikely. Those who have regained weight will often experience adverse effects on blood pressure and serum lipid levels, as well as a reduced health-related quality of life. Data was used from a complex, stratified, multistage probability sampling design from the 1999-2002 National Health and Nutrition Examination Survey (NHANES). NHANES is a continuous annual survey of the civilian non-institutionalized U.S. population.
Weight status and history were assessed through questioning. The participant’s maximum weight during their lifetime and their weight one-year prior were asked. The percentage of maximum weight lost was calculated by subtracting weight 1-year prior from their maximum weight, divided by their maximum weight, and multiplied by 100. If they had lost at least 10% of their maximum body weight during the period from maximum weight to their weight 1 year prior then they were considered to have lost substantial weight. Three categories were created to represent the weight change in the past year. Weight regain was defined as greater than 5% weight gain in the past year. Weight maintenance meant staying within 5% of their weight in the past year. Continued weight loss represented losing greater than 5% of their weight in the past year. Average daily screening time and physical activity level were assessed by questioning as well. Physical activity was categorized into four distinct values: sedentary, active (not meeting recommendations), active (meeting recommendations), active (meeting preventative weight regain levels). Sedentary meant reporting no moderate or vigorous leisure-time physical activities for 10 minutes or longer. There were three zones of “active”. Active but not meeting recommendations. This meant reporting at least one moderate or vigorous leisure-time physical activity lasting 10 minutes or longer. Active and meeting public health recommendations for improved health. This meant engaging in moderate-intensity physical activity on most days of the week for at least 30 minutes or vigorous-intensity physical activity on 3 or more days of the week for at least 20 minutes. The last category is active and meeting 2005 dietary guidelines recommendations for sustaining weight loss. This meant to participate in at least 60 to 90 minutes of daily moderate-intensity physical activity five days a week.
The factors associated with weight regain were determined by multiple logistic regression, comparing those who re- gained weight with those who did not (i.e., continued to lose weight or maintained weight). Variables included in the model were gender, age in years, race/ethnicity, education, percentage of maximum weight lost, years since reaching maximum weight, and BMI 1 year prior. Behavioral factors included smoking status, average amount of restaurant consumption per week, average amount of hours of screen time outside of work in the past 30 days, attempting to control weight in the past year, and physical activity levels. Participants were excluded if they were pregnant or were missing pregnancy information, missing information on any of the demographic, behavioral, or weight-related factors in the multivariate model. Those who reported unintentional weight loss from weight 1 year ago to current weight were also excluded. The final sample size included 1310 adults. Participation rates were 83% and data was collected from in-home interviews.
Approximately one-third of participants who experienced substantial weight loss would regain more than 5% of their body weight in the year. The factors associated with weight regain were being of Mexican American ethnicity, greater percentage of maximum weight lost, fewer years since reaching maximum weight, attempting to control weight, greater daily screen time, and not meeting physical activity recommendations.
Limitations of this study were most people who lose weight do not do so with clinical treatment and therefore this estimate of weight regain prevalence isn’t representative of the general population. Since the amount of participants that were of Mexican-American descent was only 4.9% compared to 75.8% that were non-Hispanic white, it’s difficult to determine that Mexican-Americans had a greater prevalence of weight regain than non-Hispanic whites. The broad spectrum of whites allowed for multiple variables to be associated with weight regain. For example, 10% of the white population may have been over the age of 75 and therefore linked to lower activity levels. Perhaps another 10% may have been smokers and had foregone high-intensity exercise necessary to keep weight off. However, there were only 65 participants that were defined as Mexican-American. 1,008 participants were categorized as non-Hispanic white. Since the population sizes are vastly different, it would take fifteen participants in the white population to match one participant in the Mexican-American population when considering weight regain. The study didn’t say it calculated weight regain as a total of the populations size either. For example, if 3 out of the 65 participants had weight regain in the Mexican-American population then that would calculate to 4% of the Mexican-American population experienced weight regain. It would take forty participants in the white population to calculate to 4% of the population. Since it’s predictable that a given number would see weight regain, only allowing a small number of participants from the Mexican-American population seems unfair. All ethnic categories likely would see a small number participants regain weight. However, having 15 members of the population experience weight regain is much larger, even if it is relative. At some point, it’s incomparable. Especially if we are considering that between 10% and 25% of the population regained weight. That would be 16 of the Mexican-American population and 252 of the non-Hispanic, white population. One is highly probable since all populations likely could see 16 participants regain weight but the likelihood of having 252 participants is less, even if it’s still 25% of the total. Further limitations include the bias of weight recall. Both current and past body weights are based on self-report. Recall of weight change tends to overestimate weight loss and undermine weight gains. Recall in general, whether for caloric intake or to determine intention to lose weight is biased. Finally, data was cross-sectional and therefore cannot be used to determine causation.
It’s no doubt that weight regain is a problem that contributes to obesity. Educating the general population is an important first step. However, even education isn’t always enough. Adaptive thermogenesis throws out the rule book of weight loss. The more studies and research on adaptive thermogenesis then the more fitness professionals can help. Weight regain isn’t the problem. Being unable to lose the weight after weight regain is the problem and it’s largely the fault of adaptive thermogenesis. In fact, even participants who aimed to control their weight were associated with weight regain. This shows that the original strategies that led to weight loss no longer were effective. More research needs to be placed on the adaptive capabilities of the body and the types of signals exercisers need to send to their body to reverse the weight regain.
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