Nearly two-thirds of male MPs have admitted that they feel fat and unfit - despite growing demands from Britain's politicians for a crackdown on obesity.

In a survey by the Men's Health Forum and an all-party group of MPs, a large majority of male MPs admitted they did not exercise enough and often ate unhealthy foods. Even backbenchers who thought they were at the right weight said they probably needed to exercise far more.

The findings will raise eyebrows since MPs have been calling with growing urgency for a national crusade to cope with an emerging health crisis over obesity.

Peter Baker, the chief executive of the Men's Health Forum, a campaign group, said their findings suggested MPs were setting a bad example. The survey showed that 60 per cent of the 113 male MPs who responded felt overweight and unfit - 47 of whom admitted their weight problems worried them.

"Despite all the good health messages from the Department of Health, the majority of male politicians are just like most other blokes: they're overweight, they're tempted by unhealthy foods, and they don't exercise enough," he said.

Part of the problem is that life at Westminster is too sedentary. MPs work in a "fat-friendly environment" by spending long hours in committee rooms, offices, bars and restaurants.

However, Dr Howard Stoate, the Labour MP who runs the all-party Parliamentary Group on Men's Health, suggested the problem at Westminster could be even worse than the national average. He said male obesity is worst among working-class men but since most MPs are middle-class professionals - a social group which is largely fitter than average - the figures suggest MPs are disproportionately overweight.

Recent modernisations of MPs' working hours, which have ended the traditionally very late sittings in the Commons, could actually have worsened the problem, Dr Stoate said. MPs who live far outside London now have more time on their hands in the evenings, and are more likely to go out eating and drinking.

Harry Barnes, Labour MP for Derbyshire North East, cut his weight after hitting 14 stone and having a stroke. Twice a winner of the Commons Weight Watchers prize, Mr Barnes, 67, is now 12st 10lbs but admitted: "I still don't do enough exercise. I just try to eat in the healthiest possible way."