Calls for doctors to provide routine health services seven days a week are "ridiculous", doctors leaders have said.
Dr Mark Porter, chair of council at the British Medical Association, condemned suggestions that the NHS should operate a seven-day operation for all services.
NHS England proposed that routine NHS services, including GP and hospital appointments, are to be provided on Saturday and Sundays to "offer greater customer convenience".
But Dr Porter said that the health service can "barely afford" its current model.
Speaking at the union's annual representative meeting in Edinburgh, he said: "Like many doctors here, I feel personally offended by the terms in which this debate has been couched. Like many of you I work nights and weekends as well, at times when much of the private sector is fast asleep and ministers are tucked up soundly in their beds.
"We all want urgent care at weekends and evenings to be of the same high standards as patients can expect on weekdays. But the calls we sometimes hear for a Tesco NHS, full service, 24/7, are just ridiculous when the health service can barely afford its current model."
He added: "Shops don't open on bank holidays out of a sense of public service, they open because it's a way of stimulating demand and maximising profits.
"Stimulation of demand is probably the last thing the NHS wants to do at the moment and it's not necessarily appropriate for elective healthcare. These commercial comparisons are not helpful."
Dr Porter said that the NHS is "struggling to cope" with cuts and structural change, adding: "Doctors are desperately trying to just deal with the sheer, unparalleled scale of demand on existing services."
In December last year NHS England announced that medical director Professor Sir Bruce Keogh was to establish a forum to find a way to introduce a seven-day service. Sir Bruce will report on his findings in the autumn.