some cancers (ENT, GI tract, lungs) because they result in hypercatabolism (protein requirements are higher than those of healthy people) and because the treatment can modify taste, smell and salivary secretions as well as making it difficult for the patient to eat (pain on swallowing, loss of appetite, feeling of fullness, aversion to food, nausea and vomiting)

  some other diseases (cystic fibrosis, myopathy, Alzheimer’s disease, respiratory or renal failure, malabsorption, Parkinson’s disease).

  some infections (e.g. difficulty with swallowing or chewing, poor dental health) which lead to a reduction in food intake.

  living alone, lack of physical exercise, lack of activity, depression, emotional upset and loss of independence.