The researchers used data from repeated cross-sections from successive longitudinal birth cohort studies. The studies used general population samples of teenagers in the United Kingdom who were aged 14 to 16 years that were part of 3 ongoing birth cohorts: the British Cohort Study 1970 (children born between April 5 and 11, 1970; data collected in 1986), the Avon Longitudinal Study of Parents and Children (mothers with expected delivery between April 1, 1991, and December 21, 1992; data collected in 2005), and the Millennium Cohort Study (children born between September 1, 2000, and January 11, 2002; data collected in 2015).
The study cohort was comprised of 22,503 teenagers with an average age of 14.8 years for girls. The cohort was slightly more female (53.6%) and the majority of teenagers were white (89.9%). The distribution from the 3 ongoing birth cohorts were 5878 participants from the British Cohort Study; 5832 from the Avon Longitudinal Study of Parents and Children; and 10,793 from the Millennium Cohort Study. In the Millennium cohort, 4809 (44.4%) of the participants reported dieting and 6514 (60.5%) said they had exercised to lose weight. In comparison, the British Birth cohort had 1952 (37.7%) reported dieting and 344 (6.8%) reported exercising to lose weight. Additionally, participants in the Millennium cohort (4539, 42.2%) were more likely to try losing weight than those in the Avon cohort (1767, 28.6%). Female participants were more likely to report weight loss behaviors than their male counterparts in all years, but the prevalence increased more in male participants over the course of time (lifetime dieting in boys: odds ratio [OR], 1.79; 95% CI, 1.24-2.59; in girls: OR, 1.23; 95% CI, 0.91-1.66; currently trying to lose weight in boys: OR, 2.75; 95% CI, 2.38-3.19; in girls: OR, 1.70; 95% CI, 1.50-1.92). Teenagers were also found to be more likely to overestimate their weight (boys describing themselves as overweight adjusting for body mass index, 2005 vs 1985 OR, 1.60; 95% CI, 1.17-2.19; 2015 vs 1985 OR, 1.36; 95% CI, 1.04-1.80; girls describing themselves as underweight, after adjusting for body mass index, 2015 vs 1986 OR, 0.51; 95% CI, 0.28-0.91). The researchers also found that girls who indicated that they were overweight had increasingly greater depressive symptoms over the course of time when compared to girls who stated that their weight was in the right place (mean difference 1986, 0.32; 95% CI, 0.22-0.41; mean difference 2005, 0.33; 95% CI, 0.24-0.42; mean difference 2015, 0.56; 95% CI, 0.49-0.62)
The researchers concluded that the increasing focus from public health offices on preventing obesity could have an unintended impact on weight-control behaviors and mental health. They said that future public health campaigns meant to tackle the obesity epidemic should include some focus on preventing disordered eating habits. Future campaigns should also be mindful of the mental impact they can have on teenagers.
1. Solmi F, Sharpe H, Gage S, Maddock J, Lewis G, Patalay P. Changes in the prevalence and correlates of weight-control behaviors and weight perception in adolescents in the UK, 1986-2015. JAMA Pediatr. November 16, 2020. Epub ahead of print. doi:10.1001/jamapediatrics.2020.4746