Trends in Weight Loss Efforts Among Us Adolescents With Overweight and Obesity

Document Type

Article

Publication Date

6-25-2018

Publication Title

JAMA Pediatrics

DOI

10.1001/jamapediatrics.2018.1012

ISSN

2168-6211

Abstract

Snook and colleagues1 reported recently that, despite the significant increase in the prevalence of obesity over decades, fewer US adults have tried to lose weight. However, the trend among adolescents, the population most susceptible to changes in social norms, is unclear. We assessed the trend in weight loss efforts among adolescents with overweight and obesity aged 16 to 19 years.

Methods

We used data from the National Health and Nutrition Examination Survey for this study. The 1988-1994 survey years were designated as the early period (reference), 1999-2004 as the intermediate period, and 2009-2014 as the recent period. After excluding 554 adolescents who were underweight (body mass index, 2 were used to translate directly measured weight and height into sex- and age-specific body mass index percentiles and categorized adolescents as obese (≥95th percentile), overweight (85th-94th percentile), or normal weight (5th-84th percentile). The main question of interest, “During the past 12 months, have you tried to lose weight?” was asked directly in the 1988-1994 surveys. However, a skip pattern was incorporated with this question starting in the 1999-2000 survey. Adolescents whose self-reported body weight for 1 year ago was 4.54 kg or more than their self-reported current weight and reported this change as intentional were presumed to “have tried to lose weight in the past 12 months” and the question about having tried to lose weight was skipped. The question of interest was asked of all others, including those with an unintentional weight loss of 4.54 kg or more. Because the percentage of adolescents trying to lose weight, on average, was substantially above 10%, logistic regression cannot be justifed.3 Therefore, predicted population margins (PPM) were used to estimate the differences in the percentages of individuals trying to lose weight over the survey period. Bonferroni multiple comparison test was performed to test the percentage difference of adolescents trying to lose weight between the levels of variables, including survey period, after correcting for body mass index percentile, race/ethnicity, and family income. With appropriate weighting and nesting variables, analyses were conducted using SAS, version 9.4 (SAS Institute). Two-sided P values below critical points (.05 for trend test) were considered statistically significant.

Results

The prevalence of overweight and obesity increased from 22.09% (95% CI, 18.20%-25.98%) in 1988-1994 to 36.17% (95% CI, 32.74%-39.60%) in 2009-2014; during the same period, the overall percentage of adolescents who had tried to lose weight decreased from 33.68% (95% CI, 29.19%-38.17%) to 32.74% (95% CI, 29.60%-35.88%). For adolescents with overweight, the percentage trying to lose weight decreased from 36.36% (95% CI, 13.86%-58.85%) in 1988-1994 to 31.30% (95% CI, 22.65%-39.95%) in 2009-2014 among boys and from 80.24% (95% CI, 69.09%-91.39%) in 1988-1994 to 59.14% (95% CI, 50.41%-67.86%) in 2009-2014 among girls (Figure). After adjustment for race/ethnicity, family income, and body mass index percentile, the percentage of girls with overweight trying to lose weight decreased by 12.11 percentage units (PPM = −12.11%; 95% CI, −24.74% to 0.52%; P = .06) between 1988-1994 and 1999-2004 and further down by 21.94 percentage units (PPM = −21.94%; 95% CI, −35.14% to −8.74%; P < .001) by 2009-2014 (P for trend < .001; Table); no significant decrease was observed among boys with overweight (P for trend = .44) despite an 8.01–percentage unit decrease (PPM = −8.01; 95% CI, −28.70% to 12.69%) during the entire study period. For boys with obesity, the percentage trying to lose weight decreased from 67.51% (95% CI, 50.92%-84.10%) in 1988-1994 to 51.01% (95% CI, 42.24%-59.78%) in 1999-2004, then increased to 66.82% (95% CI, 58.65%-74.98%) by 2009-2014. The corresponding percentages among girls with obesity were 69.50% (95% CI, 52.40%-86.61%) in 1988-1994, 69.45% (95% CI, 62.12%-76.79%) in 1999-2004, and 64.31% (95% CI, 52.92%-75.69%) in 2009-2014; no statistical significance was detected after multivariable adjustment for either sex with obesity.

Discussion

Fewer US adolescents with overweight tried to lose weight in 2009-2014 compared with their counterparts interviewed in 1988-1994, potentially compromising opportunities to prevent overweight from becoming obesity. With more than one-third of adolescents having overweight or obesity, it is cognitively difficult to view overweight as abnormal.4 More adolescents with overweight or obesity seem satisfied with their weight and not ready or motivated to engage in weight loss efforts.5 Failure among pediatricians to discuss weight issues with adolescents may also contribute to the decreasing trend.6 With small sample sizes, the self-report nature of this study, and differences between the participants who were included and those who were excluded, the generalizability of the conclusion might be jeopardized. It is not clear whether the decreasing trend to lose weight led to an increased prevalence of overweight and obesity or vice versa. Sex differences in the trend warrant further investigations.

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