Prevalence of obesity and comorbid eating disorder behaviors in South Australia from 1995 to 2015

BACKGROUND: Obesity and eating disorders are often studied and treated separately. While the increases in obesity prevalence are well known, examination of its co-occurrence with eating disorders, a problem also of public health concern, is important because eating disorder behaviors are known to contribute to obesity onset and maintenance, and vice versa. METHODS: Data from large cross-sectional representative statewide community samples of people in the years of 1995 (n = 3001), 2005 (n = 3047) and 2015 (n = 3005) were analyzed. Data were collected using a structured, self-report interview that included demographic, health-related, weight, height and eating disorder behavior questions. Eating behavior questions assessed binge eating, very strict dieting/fasting and purging, and were derived from the Eating Disorder Examination. Logistic regression analyses were conducted comparing prevalence of obesity, eating disorder behaviors and their co-occurrence. RESULTS: The prevalence of obesity or binge eating, or obesity with comorbid binge eating, each increased significantly from 1995 to 2005 (P < 0.001 for each comparison) and continued to increase significantly from 2005 to 2015 (P < 0.001 for each comparison). The highest increases from 1995 to 2015 were in the prevalence of obesity with comorbid binge eating (7.3-fold), or obesity with comorbid very strict dieting/fasting (11.5-fold). The prevalence of very strict dieting/fasting also increased significantly from 1995 to 2015 (3.8-fold). The prevalence of purging, or obesity with comorbid purging, did not change significantly from 1995 to 2015. CONCLUSION: There were statewide increases during the 20 years from 1995 to 2015 in the independent prevalence of obesity, binge eating and very strict dieting/fasting, and even higher increases in the prevalence of obesity with comorbid binge eating, and obesity with comorbid very strict dieting/fasting. These findings support the need for more integrated approaches to both the prevention and treatment of obesity and eating disorder behaviors, namely binge eating and very strict dieting/fasting.