Disordered eating behaviors (DEB) impact on health and wellbeing worldwide. This study aimed to examine sociodemographic trends in the prevalence of DEB over 20 years in the Australian general population.

Data were derived from five sequential cross-sectional surveys (1998, 2008, 2009, 2016 and 2017) with population-representative samples of adults and adolescents residing in South Australia (N = 15 075). DEBs investigated were objective binge eating (OBE), strict dieting/fasting, and purging. Sociodemographic data included gender, age, educational level, work and marital status, and residence.

OBE prevalence increased significantly. Strict dieting/fasting also increased from 1998 to 2008/9 but remained stable between 2008/9 and 2016/7. Purging prevalence did not change significantly over time. All survey years were associated with a significantly higher odds of OBE, and strict diet/fasting compared to 1998. Lower age, a higher Accessibility Remoteness Index of Australia (ARIA) score, higher body mass index (BMI), higher educational attainment, and not being in a married or de facto relationship were independently associated with greater adjusted odds for endorsing OBE. Younger age, female gender, and higher BMI were also independently associated with greater adjusted odds for endorsing strict dieting/fasting.

The increased prevalence of DEBs in various strata of Australian society has both public health and clinical implications. The results refute the stereotype that eating disorders (EDs) predominantly affect young women. They build impetus for future research on EDs among men and older individuals, with a view to developing tailored public health and clinical interventions for these populations.