A High Court judge was asked to rule that force-feeding would not be in the "best interests" of an anorexic woman whose weight is just over three stone.
Mrs Justice Eleanor King, sitting at the Court of Protection in London, heard that the "highly intelligent" 29-year-old did not wish to die, but "suffers with serious and enduring anorexia nervosa".
Now weighing around just 3st 2lb (20kg), she has suffered from anorexia from the age of 12 - and since turning 14 has spent 90% of her life as an in-patient.
Details of the "parlous state" of the woman, who cannot be named for legal reasons, but is referred to as L, were given as an NHS trust asked the judge to make a declaration that it would "not be in her best interests" for L to be subjected to "forcible feeding".
Bridget Dolan, for the trust, said the case, from the north of England, involved "a serious medical treatment matter".
Describing the seriousness of the woman's condition, Dolan said: "It has reached a point where the NHS trust who have her physical care are of the view that force-feeding is not in her best interests, notwithstanding that it is probable that if not fed she will die."
She was in a psychiatric unit until March when "her physical state became such that it was believed she was likely to die without physical treatment".
Her BMI (body mass index) is at the "extremely low level" of 7.7, said Dolan, adding: "To some extent she has defied expectations and continued to live at such a low weight."
Dolan said L has no wish to die. She "doesn't express a wish to die and that is certainly not part of her motivation in refusing nutrition and hydration".
But her severe anorexia - a condition which creates a "morbid fear" of ingesting any calories that might lead to an increase in weight - "does not allow her to eat".
Dolan said the woman was "only agreeing" to receive 600 calories a day through a tube, which was "insufficient to maintain her current weight and certainly could not allow her to put on weight".
She told the court: "The issue is what do the doctors do? Do they force-feed her against her wishes, or do they allow her to be the barometer by which the decision about how much nutrition she takes in is made."