Malnutrition is a "very big problem" in the UK, experts warned, as they set out a guide to prevent the condition in older people.
Most people think of the condition as a "third-world problem" but one in ten older people in the UK is malnourished, the British Dietetic Association and the Malnutrition Task Force said.
Officials said that tackling malnutrition in adults could save the NHS as much as £45.5 million a year.
"For far too long, malnutrition and dehydration has been thought of as a third-world problem," said Helen Davidson, honorary chair of the British Dietetic Association - the professional body for UK dietitians.
"The reality is, malnutrition and dehydration is a very big problem here in the UK."
Malnutrition Task Force chair Dianne Jeffrey added: "One in ten older people are malnourished and 93% of them are in the community. This is where it starts for many people, so we must make every effort to improve prevention and early detection of malnutrition.
"There are many different causes and factors that contribute to malnutrition and addressing them requires the concerted effort of all stakeholders.
"Together, we can combat preventable malnutrition effectively and thus improve the health of older people, maintain their independence and save money for the local health economy too."
Malnutrition, which is thought to affect three million people in the UK, is a serious condition that occurs when a person's diet does not contain the right amount of nutrients.