Malnutrition is no longer only a problem for poor countries, said experts who warned that more than a million older people in the UK could be affected by the condition.
More must be done to tackle the condition which occurs when a person's diet doesn't contain the right amount of nutrients, the Malnutrition Task Force said.
The group said that the problem is "often overlooked".
The comments come as a new poll released by the body found that many health workers do not believe that the issue is a priority in their organisation.
The survey of 1,500 health and care workers across the UK found that only 51% said malnutrition was a priority in their organisations.
Worryingly, only 47% felt confident that their knowledge and skills were sufficient to help people most at risk, the poll found.
Experts say that around 1.3 million older people in the UK suffer from malnutrition.
Dianne Jeffrey, who chairs the Malnutrition Task Force and charity Age UK, said: "Eating and drinking well is a vital part of maintaining good health and independence.
"And while we generally think of malnutrition as a problem for low income countries, the sad fact is that many older people in the UK today are malnourished or at risk of becoming so.
"Malnutrition is a really knotty problem. While many of the interventions are relatively simple, to be really effective they require a wide range of services to come together, recognise the problem and each make a contribution towards tackling it.
"However, at the moment the sad fact is in too many areas this isn't happening. Malnutrition is often overlooked and isn't tackled very effectively at any point in the care journey, so many people slip through the net and never receive proper help."
The organisation has set up a series of pilot schemes to see how the problem can be tackled, including new programmes that identify at-risk people, providing support for people at mealtimes and offering free internet home shopping training sessions for older people who were finding it difficult to get out and shop.
Ms Jeffrey added: "The pilots have shown us just what can be achieved when we all work together to put malnutrition at the top of the agenda.
"The challenge now is to make sure that every area steps up to ensure that all older people are well nourished and get the help they need."
A Department of Health spokesman said: "An increase in cases of malnutrition being reported in recent years is in part due to much better diagnosis and detection.
"We have provided £500,000 funding to Age UK to reduce malnutrition among older people through the Malnutrition Taskforce and will continue to train all health staff to spot the early warning signs so that effective action plans can be put into place. We will continue to increase awareness of it among staff as a priority."