The "frail" patient lost a "significant amount" of weight as a result of the blunder at the Victoria Hospital in Kirkcaldy, Fife, in December last year.
Patients' campaigners expressed anger at the treatment of the patient, saying they could think of no reason why, in the circumstances, the person was denied food.
The incident was revealed in a report by Healthcare Improvement Scotland following an unannounced visit to the hospital.
The report said the unnamed patient was assessed as being "unsafe to swallow food or drinks" by staff. After several failed attempts to fit the patient with a feeding tube, staff decided the person would not receive "nutritional support".
The patient continued to receive fluids to prevent dehydration and antibiotics through a drip.
Inspectors were told NHS Fife had "no policy or pathway" for patients who could not eat or drink.
The report also revealed that a nurse had taken a meal to the patient despite being told they could not swallow and that doing so posed a potential risk.
Healthcare Improvement Scotland said: "We brought these issues to the attention of the senior charge nurse of the ward and escalated this to the head of nursing for emergency care for medicine. Immediate action was then taken to review the patient's care."
Dr Jean Turner, of Scotland Patient Association, described this incident as "very distressing". "I can't think of anything worse than being allowed to drift away because you have had no nutrition."
NHS Fife said they were unable to comment on the care of individual patients.