Fat, sugar and salt will not be limited as part of a new HSE food policy.
Adult patients will soon be screened when they are admitted to hospital and get an assigned menu.
For the regular diet, the HSE said foods high in fat or sugar may make a "useful contribution" to the overall diet.
The aim of the new policy being launched later today is to improve the quality and safety of hospital food.
The HSE's Margaret O'Neill said improved nutrition can speed up recovery time.
Ms O'Neill said: "So we know that one in four people coming into hospital are actually malnourished or at risk of malnutrition and that's not something we really hear about.
"So it's really moving through their nutritional care into part of the clinical treatment for patients and that is a really important message from the policy, as well."
The new hospital nutrition plan says that patients must have at least five servings of fruit and vegetables a day.
Ms O'Neill said the scheme will also cut down food waste.
She said: "What we're looking at is the meals and the snack that are provided in hospitals. Our hospital menu is going to recommend three meals and two snacks, plus eight cups of fluids. We are providing those meals at the minute, but we also know that there is a lot of waste in hospital food.
"We are working with a whole range of people, our chefs, catering managers, dieticians to try and ensure that patients are eating their food so there is less waste and we know that there is about €7m wasted on food in Irish hospitals."