Food served around the clock and digital menus are among the recommendations in a review of hospital meals led by celebrity chef Prue Leith.
It is possible to serve "delicious, nutritious" food on a budget, the Great British Bake Off judge said.
The review was launched after a deadly outbreak of listeriosis in hospitals last year was linked to pre-packaged sandwiches and salads.
Boris Johnson said it was "therapeutic" for patients to have good food.
A group of advisers, tasked with reviewing hospital food, set out ways NHS trusts can prioritise food safety and provide healthier meals.
Recommendations included upgrading kitchens to provide 24/7 service that caters for a variety of needs, from new mothers in a maternity ward, to patients hungry after a long fast due to surgery, and staff working overnight.
Leith said: "The review provides best-in-class examples of how hospitals can serve delicious, nutritious and nicely presented meals on a budget.
"Food is not only important to health, but to morale. Hospital mealtimes should be a moment of enjoyment and a pleasure to serve. They should inspire staff, patients and visitors to eat well at home."
The prime minister said: "It's massively important for patients and for staff that they should have hot and nutritious meals available in the wards and across hospitals at all times of the day."
It is "therapeutic, it's beneficial" for patients to have good quality food, he added.
He visited the Royal Berkshire Hospital in Reading with Leith and Health Secretary Matt Hancock on Monday to mark the launch of the review. On the visit, he said that in the 40 new hospitals being constructed or rebuilt "there will be kitchens and facilities on the wards so people can get hot toast at all times of the day".
The review said introducing digital menus and food ordering systems that factor in a patient's needs could improve communication between dieticians and caterers, reduce food waste and provide patients with the right food for recovery.
An agreed set of national professional standards for NHS chefs - with mandatory professional development, including appropriate compulsory food hygiene and allergen training - was also recommended in the review.
Increasing the role of nurses, dieticians, caterers and staff wellbeing leads in overseeing food services could help to make sure nutritious meals are part of patients' recovery plans, the report said.
Henry Dimbleby, co-founder of Leon Restaurants and independent lead on the National Food Strategy, said hospitals must be a "guiding light" in efforts to "get to grips with the slow-motion disaster that is the British diet".
NHS chief executive Sir Simon Stevens said "every meal that patients get in hospital should be appetising and nutritious" and that the NHS should play its part in tackling the nation's obesity crisis.
The government is putting together an expert group of caterers, dieticians and nurses to decide on next steps.