Background The aim was to investigate trends in obesity prevalence by gender and educational level in the general population aged 30-69 years, based on large surveys conducted in Mid-Sweden in 2012, 2017 and 2022.Methods The study included 22 082, 15 264 and 17 055 respondents, respectively. Obesity (body mass index >= 30 kg/m2) was based on self-reported weight and height. Trends in obesity prevalence, including comparisons across educational levels, were estimated by age-standardised proportions with corresponding 95% CIs. Differences between genders, educational levels and survey years were tested using multiple logistic regression.Results The overall age-standardised prevalence of obesity increased from 17.6% in 2012 to 20.1% in 2017 and to 23.3% in 2022. There was no statistically significant difference in obesity prevalence between men and women. Large and persisting inequalities between educational levels were however observed. In 2022, the prevalence of obesity was about 30% among persons with low/middle education and 18% among persons with high education.Conclusion Efforts to tackle the obesity epidemic are urgently required in Sweden, taking into consideration the circumstances of groups with low and middle levels of education.