Serious concerns have been raised about the way some NHS hospitals treat elderly people - including one where patients are prescribed water to make sure they get a drink.
The Care Quality Commission (CQC) said three hospitals had broken the law by failing to meet essential standards of care on dignity and nutrition.
The Royal Free Hospital in London, the Alexandra Hospital in Worcestershire and Ipswich Hospital have been given 28 days to improve.
The CQC is inspecting 100 hospitals in England. Reports from the first 12 are published today.
Inspectors expressed "major" concerns about nutrition at the Alexandra Hospital in Worcestershire, which is part of the Worcestershire Acute Hospitals NHS Trust.
They found "meals served and taken to the bedside of people who were asleep or not sitting in the right position to enable them to eat their meal".
Hot dinners and puddings were left for 15 minutes to go cold before staff found time to assist patients.
Staff said they sometimes had to prescribe drinking water on medication charts to "ensure people get regular drinks".
At Ipswich Hospital NHS Trust, inspectors found patients left in night clothes all day and not always taken to the toilet away from where they slept.
Records were not always up-to-date and staff spoke among themselves when caring for patients rather than to the patient.
Staff reported being too busy and over-stretched to provide the care they wanted to, inspectors noted.
Some patients were put to bed at 6pm even though they did not want to be.
At the Royal Free Hospital in Hampstead, west London, inspectors found staff did not always make sure people had enough to eat and drink.
While many patients got help with eating, some did not and had their trays taken away, and staff rarely asked patients if they had enough to drink.
Food and fluid charts were often "inaccurate, not completed and not up-to-date", inspectors found.
Chair of the CQC Jo Williams said most hospitals provided good care, but at others staff showed a lack of compassion.
"These are not difficult things to get right," she said.
"The fact that staff are still failing to do so is a real concern."
Health Secretary Andrew Lansley said: "Everyone admitted to hospital deserves to be treated as an individual, with compassion and dignity.
"We must never lose sight of the fact that the most important people in the NHS are its patients."
Chief Executive of the Royal College of Nursing (RCN) Dr Peter Carter said: "Some of the concerns raised in this report are truly shocking and we are clear that there is simply no excuse for failing to treat patients with the respect and dignity they deserve.
"We know that there are relatively small pockets of the NHS that do not deliver good nursing care and this is unacceptable."