disorders of nutrition
Overview of Nutritional Support
Determining Nutritional Requirements
(See also Nutritional Requirements .) Before starting nutritional support, doctors must first determine the amount and mix of nutrients the person needs. People need a certain amount of nutrients for energy, which is measured in Calories . The number of calories people need varies depending on the following: Their weight Their activity level The demands created by illness The mix of nutrients typically includes Carbohydrates, Proteins, and Fats , Usually, doctors estimate the person's needs using equations based on the person's weight, height, age, sex, and activity level. Doctors adjust the requirements if the person has a condition that increases the need for calories, such as a serious illness, kidney failure that requires dialysis, an infection, an injury, or recent surgery. Some centers use a special technique to obtain a more accurate estimate. This technique measures how much oxygen is inhaled and how much carbon dioxide is exhaled—an indication of how much energy the body is using. People who are over 70 years old may need extra protein. Certain conditions, such as serious illnesses, kidney failure, infections, injuries, and surgery, and older age can increase the need for nutrients. 