Malnutrition or undernutrition, according to the Merck Manual Online Library, is the result of an inadequate supply of nutrients due to impaired metabolism, malabsorption or an inadequate supply of food. Overnutrition, or obesity, according to Merck, is also a form of malnutrition. Malnutrition occurs in stages: First blood and tissue changes occur, then metabolic processes go awry and finally signs and symptoms occur.
Undernutrition Risk Factors
Undernutrition is associated with poverty and social deprivation. It is also associated with infants, early childhood and adolescence, pregnancy, breastfeeding mothers and the elderly. Each of these groups requires an increased demand for nutrients to support the high metabolic state of the particular stage of life or health condition. The elderly are at risk due to changes in their metabolism, inability to cook or feed themselves and changes in appetite.
Changes in Body Mass
Sarcopenia, or the progressive loss of lean body mass, normally begins shortly after age 40. Men will lose approximately 22 pounds of lean muscle mass and women will lose around 11 pounds. Abnormal loss of lean body mass, such as that found in malnutrition, is responsible for the many complications of undernutrition, such as an increase in susceptibility to infections. Overnutrition, on the other-hand, increases total body fat and places excess fat around the internal organs.
Poor Wound Healing
One of the effects of malnutrition is poor wound healing. When the body does not get enough protein, carbohydrates and vitamins, it cannot heal. According to the Cleveland Clinic, malnutrition can impair healing, increase the possibility of infection and increase the time it takes to recuperate from a disease or surgery. Overnutrition, or obesity, is also associated with poor wound healing. Poor oxygenation of tissues, inability to provide necessary nutrients and white blood cells, and increased tension on wound edges affect wound healing in the obese patient.
Cachexia, or severe weight loss, is evidenced by shrinking muscle mass and protruding bones. The skin becomes dry and inelastic, and the hair falls out. The risk of pressure ulcers and hip fractures increases with cachexia.
According to the Merck Manual Online Library, other effects of malnutrition include edema, anemia and jaundice. Liver, kidney or heart failure may occur. Pneumonia, gastroenteritis and urinary tract infections as well as sepsis are possible as a result of malnutrition. The metabolic effects of overnutrition, or obesity, include heart disease, diabetes, stroke, high blood pressure and certain cancers.