Abstract Background People with intellectual disability have significantly higher age-adjusted rates of mortality and morbidity (including obesity) than their non-disabled peers. They are also significantly less likely to be physically active. Methods Secondary analysis of de-identified cross-sectional data from the first two waves of Understanding Society , a new longitudinal study focusing on the life experiences of UK citizens. Interviews were undertaken with 50,994 individuals aged 16 and over in Wave 1 and 54,585 in Wave 2. Of these, 520 participants age 16–49 (1.8% of the unweighted age-restricted sample) were identified at either Wave 1 or Wave 2 as having self-reported intellectual impairments. Results British adults with self-reported intellectual impairments have higher rates of obesity, inactivity, tobacco and alcohol use and poorer nutrition than their non-disabled peers. Adjusting risk estimates for between group differences in age, gender and exposure to material hardship indicated that a significant proportion of their increased risk of obesity, tobacco use and poorer nutrition may be attributable to their poorer living conditions (rather than their self-reported intellectual impairments per se). Conclusions People with intellectual disabilities should begin to be regarded as a ‘vulnerable’ group in the context of public health policy and practice.