Malnutrition contributed to the death of at least 20 people in Tayside and Fife last year — and has played a part in nearly 500 deaths in Scotland over the last five years.
Figures released under freedom of information legislation have revealed that malnutrition has been a factor in 487 deaths since 2007. Most of these — 359 — were people over the age of 65.
It has been directly responsible for killing 40 people since 2007.
In Fife, malnutrition was a contributory factor in the deaths of at least 11 people in 2011 and at least 65 over the past five years.
The figures may actually be higher as the health board — concerned about breaching patient confidentiality — has not released exact figures for years when there were very low numbers of deaths.
In Tayside, malnutrition contributed to the deaths of six people over 65 last year and at least 17 since 2007.
Charity Age Scotland said more must be done to identify the symptoms of malnutrition at an early stage.
A spokesman said: ''Many older people actually enter hospital and other care settings in malnourished states for a variety of reasons.
''Screening on admission is therefore paramount so that ward staff are aware that a patient has difficulties and that they can help that patient to eat, something that can be especially valuable with older or vulnerable patients."
Malnutrition can leave people with severely weakened immune systems, making them more vulnerable to disease.
Scottish Labour health spokeswoman Jackie Baillie said the Scottish Government must act to end what many would consider a ''third world'' problem as many elderly people will still have to choose between heating and eating this winter.
''The Scottish Government must act and quickly before this winter puts thousands more Scots in the unenviable position of choosing between warmth and hunger,'' she said.
A Scottish Government spokeswoman said steps are already being taken to reduce the effects of malnutrition.
''Between 30% and 40% of patients are either malnourished or at risk of malnourishment when they are admitted to hospital — that is why Scotland was the first country in the UK to make screening for malnutrition a mandatory requirement,'' she said.
''One death from malnutrition is one too many, so we have committed over £1.75 million to ensure malnutrition screening of all patients, the funding of nutrition champions in every NHS board and the introduction of protected meal times — enforced by senior charge nurses — to make sure patients who need help with eating are properly cared for.''