Objectives To assess the proportion of the adult obese population in Great Britain who would describe their weight using the terms ‘obese’ and ‘very overweight’ in 2007 and 2012, and identify factors associated with more accurate weight perceptions.

Design Analysis of weight perception data from two population-based surveys.

Setting Population surveys conducted in Great Britain.

Participants Survey respondents (N=657) whose self-reported weight and height placed them in the obese category: body mass index (BMI) ≥30.

Primary outcome measure Self-identification using the terms ‘obese’ and ‘very overweight’.

Results The proportion of obese adults selecting the term ‘obese’ to describe their body size was very low in both women (13% in 2007 and 11% in 2012) and men (4% in 2007 and 7% in 2012) and did not change significantly. Recognition of a substantial degree of overweight (as indexed by endorsement of either of the terms ‘obese’ or ‘very overweight’) declined substantially in women, from 50% in 2007 to 34% in 2012. It was not significantly changed in men (27% in 2007 and 23% in 2012). Having a higher BMI, and being able to identify the BMI threshold for obesity were associated with self-identifying as obese or very overweight.

Conclusions The majority of the adult obese population of Great Britain do not identify themselves as either ‘obese’ or even ‘very overweight’. Public health initiatives to tackle obesity are likely to be hampered by this lack of recognition of weight status. It is important to understand whether moves to increase personal awareness of weight status in the obese population can facilitate beneficial behaviour change, and what role health professionals can play in increasing awareness of weight status in obese patients.