Laziness should be classed as "disease in its own right", say experts.

"Given the significant associated mortality and morbidity, we propose that perhaps physical inactivity should also be considered for recognition as a disease in its own right," a pair of British doctors Richard Weiler and Emmanuel Stamatakis said.

Obesity is already classed as a disease by the World Health Organisation, noted Weiler, a specialist registrar in sports and exercise at Imperial College Healthcare.

But he said obesity was often at least partially the result of a deeper cause - not doing enough exercise.

"Money is pumped at treating the symptoms of physical inactivity - at obesity, diabetes, hypertension, heart disease - but not at the root cause," said Weiler.

The evidence showed that lack of fitness was the root cause of more illness than being fat, reports telegraph.co.uk.

Weiler said recent studies showed only one in 20 people took the minimum amount of recommended exercise, but there was still "no co-ordinated plan" to tackle the problem.