London, Nov 12 (IANS): Most people, including health care professionals, are unable to identify healthy weight, over-weight or obese people just by looking at them, says a research.

Viewing people with heavy body weight may influence what we see as normal and healthy weight and even causes people to underestimate a person's weight, the researchers found.

"Over the last 30 years we have seen changes to population body weight, so examining how this has affected how we view our own and other people's body sizes is an interesting area of research," said researcher Eric Robinson from the University of Liverpool in Britain.

The researchers asked participants to look at photographs of male models and categorise whether they were healthy weight, over-weight or obese according to World Health Organization (WHO) Body Mass Index (BMI) guidelines.

They found that the majority of participants were unable to correctly identify whether they were a healthy weight, over-weight or obese.

Participants underestimated weight, often believing that over-weight men possessed a healthy weight.

In a related study of health care professionals, the researchers found that GPs (General Practitioners) and trainee GPs were also unable to visually identify if a person was over-weight or obese.

"Our study of GPs found a tendency to underestimate weight which has important implications as it means that over-weight and obese patients could end up not being offered weight management support or advice," Robinson concluded.

The study of GPs was published in the British Journal of General Practice.