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.International Journal of Obesity advance online publication, 18 April 2017; doi:10.1038/ijo.2017.79.