Overweight patients and smokers could be bound by agreements to diet or quit cigarettes under a new policy to be debated at this year's Labour Party Conference.

A policy document, which will form the next stage of NHS reforms, says patients will have to sign contracts with GPs in return for treatment. Under new contracts to force patients to acknowledge their responsibilities for their own health, people could have to agree to give up junk food in return for care for high cholesterol or other health problems.

The patient-doctor agreement would guarantee a level of patient care, including appointments within 48 hours and "higher standards" of treatment, but the Labour document says that in return for greater services patients must "recognise the duty they owe in return".

"Not only could this new agreement set out clearly the standard of care the patient can expect to receive, but it would also remind the patient of the reciprocal nature of their relationship with their doctor. It would involve people in their own care, asking them to share the responsibility of their own healthcare and well-being," it says.

The document singles out smokers and overweight people among the groups who will face the new demands from doctors for a lifestyle change in return for NHS treatment.

However, it is likely to be seized on by Labour backbenchers and Opposition politicians of a penny-pinching approaching to healthcare that will penalise people from low-income areas.