Obesity affects one in five children in the United States. Many of the cardiovascular consequences experienced by obese adults, such as high cholesterol levels, hypertension and heart disease, are preceded by abnormalities that begin in obese children. Obesity is a contributing factor to other diseases such as Type 2 diabetes, gallbladder disease, osteoarthritis, respiratory problems and certain types of cancer. Underweight children are more susceptible to recurrent respiratory or gastrointestinal infections. These infections increase caloric needs and lower dietary intake, leaving the child more malnourished and increasing his or her vulnerability to repeat infection.
Micronutrient deficiencies complicate undernutrition and cause anemia and rickets.
Iron and calcium deficiencies increase lead absorption, a common problem in shelter housing. Increased lead absorption causes constipation, abdominal pain and anorexia, further complicating the child's undernutrition. Zinc deficiency impairs growth. Chronic undernutrition in the child's first two years can limit brain size, neuronal number and synaptic complexity. Brain weight and head circumference increase more during the child's first two years than at any other post-natal stage.