Thank you for writing to us, Brief answer - A state where an individual s intake of nutrients is insufficient for the body s normal functioning. The body needs a regular intake of many nutrients such as calcium and phosphorus for bones and protein for muscles and energy Detailed answer - If your doctor considers that you are suffering from a lack of nutrition, he/she will weigh you and make a full assessment of your diet. You may also have blood tests to look for anemia and to measure levels of specific nutrients. Investigation such as contrast X-Rays of the gastrointestinal tract may be carried out to test for underlying digestive disorders. If the deficiency is severe you will be admitted to hospital where nutrients will be administered using a tube passed through the nose into the stomach or through a drip directly into the bloodstream. If the deficiency is the result of a treatable physical problem, it should be cured with treatment. Changing your diet will resolve the problem if poor eating habits are the cause. In some cases, eg. Crohn s Disease or gastric bypass, longterm vitamin and mineral supplementation will be required.