A committee of MPs variously described as "cuddly" and "portly" left Westminster yesterday to tackle the growing national problem of obesity.

After listening to expert witnesses in the Commons, the group took to the streets of Leeds, guided by a 14-stone teenage girl and assistants recruited by the local health authority.

"It's really nice," Sophie Henderson, 15, told David Hinchliffe, Labour MP for Wakefield and chair of the Commons select committee on health.

"They've given me a step-counter and I've done more than a million steps already. I do lots more walking and I'm steadily losing weight."

Sophie's scheme is supervised by Leeds University specialists and is one of a series of projects which MPs are examining, prompted by concern over the increase in obesity.

The free, publicly funded Watch It pilot scheme was prompted by a survey in 2001 which found that a third of the city's 11-year-olds were overweight and one in five was obese. It now helps 49 children.