Causes of Undernutrition

Cause

Examples

Lack of access to food

Inability to obtain food (for example, due to lack of transportation or physical impairment)

Poverty

War, drought, flooding, and famine

Conditions that restrict the amount or type of food eaten

Fad diets

Some vegan or vegetarian diets

Voluntary restriction of calories (as for a strict reducing diet or a fast)

Conditions that interfere with the intake, metabolism, or absorption of nutrients

AIDS

Alcohol use disorder

Anorexia nervosa

Cancer

Depression

Diarrhea

Substance use disorders

Kidney failure

Impaired mental function, such as dementia

Inflammatory bowel disorders (such as Crohn disease and ulcerative colitis)

Liver disorders

Malabsorption disorders

Sometimes surgery to promote weight loss (bariatric surgery)

Vomiting

Medications that interfere with the consumption, metabolism, or absorption of nutrients

Some medications used to treat anxiety, high blood pressure, heart failure, an underactive thyroid gland (hypothyroidism), asthma, or cancer

Conditions that greatly increase the need for calories

Demanding exercise, such as rehabilitation or training for athletic competition

Injury, such as burns

High fever

Infections that are widespread or severe

Growth and development in infants, children, and adolescents

An overactive thyroid gland (hyperthyroidism)

Pregnancy and breastfeeding

Surgery

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