Background Changes over time of mean body weight or prevalence of overweight and obesity have been well documented. Less consideration has been given to describing the distribution to these changes particularly by socioeconomic status (SES). Our aim is to examine how the distribution of body weight has changed at the population-level for England by SES.

Methods We used data from the Health Survey for England for the years 1992–2013 (mean annual sample size 10,418) to calculate the median, 5^th and 95^th percentiles, and standard deviation of body mass index (BMI). The standard deviation informs about dispersion of values, whilst the percentiles allow us to explore what might be driving any dispersion. We measured socioeconomic status by level of education. We tested differences using analysis of variance (ANOVA) and quantile regression (to allow calculation of 95% confidence intervals of our estimates). Analyses were stratified by sex and level of education.

Results We find evidence of increased dispersion with increasing values of standard deviation for BMI over the period for each educational group by sex. Significant differences in variances by educational level were observed for males (range of F-values; 6.78–35.19) and females (15.19–120.26) for each year. Trends in median BMI demonstrated rising median BMI between 1992 and 2001, before beginning to slow down (this trend was consistent by sex and education). Whilst the 5^th percentile remain flat over the period, the 95^th percentile continued to rise throughout the whole period for each sex-specific educational group.

Conclusion Our results suggest that the slowing down of median BMI hailed by some public health officials may not be quite the success it first appeared. Failing to understand the distribution of body weight in the population will hamper our projections of future patterns, as well as our ability to design effective public health strategies. The consistency of findings by educational level suggest the need for further research into understanding these diverging trends.