Overnutrition and undernutrition can contribute to many common diseases or disorders in the elderly. Some conditions may take years to develop, while others can occur within weeks. Protein energy malnutrition may be the direct result of poor diet, or it may develop indirectly when other illnesses increase nutritional requirements beyond usual needs. One of the most easily recognised consequences of overnutrition is obesity, which is a risk factor for other diseases such as non-insulin-dependent diabetes mellitus, cardiovascular disease and hypertension. If nutritional disorders are identified and managed appropriately, the health of many elderly people can be significantly improved.