An NHS Constitution that sets out a patient's legal rights and obligations is to be unveiled by Prime Minister Gordon Brown and Health Secretary Alan Johnson.
Mr Johnson has said that it will include measures to tackle obesity, although they will not be legally enforceable or deny treatment to overweight people.
"We have got a section in there on personal responsibilities," he said, "but it's not something that's backed up by law, and therefore you won't have the broccoli police come round if you are having a fry-up."
He said that underlining the dangers of alcohol and benefits of a balanced diet can be tackled in other ways, and that the NHS will continue on the basis that "if you have a health problem, we will deal with it".
He said that the NHS Constitution "was never meant to be something that changed the health service and made it less acceptable to people, and made it more problematic".
The document is likely to set out the right of patients to seek care abroad if they face undue delay in England.