Nutrition disorders are diseases that occur when an individual's dietary intake doesn't contain the proper amount of nutrients for healthy functioning, or when an individual cannot correctly absorb nutrients from food. Nutrition disorders are often caused by undernutrition, overnutrition or an incorrect balance of nutrients.The most significant nutrition-related disease is chronic undernutrition, which plagues quite 925 million people worldwide. Undernutrition may be a condition during which there's insufficient food to satisfy energy needs; its main characteristics include weight loss, failure to thrive, and wasting of body fat and muscle. Low birth weight in infants, inadequate growth and development in children, diminished mental function, and increased susceptibility to disease are among the various consequences of chronic persistent hunger, which affects those living in poverty in both industrialized and developing countries. Malnutrition is that the impaired function that results from a protracted deficiency—or excess—of total energy or specific nutrients like protein, essential fatty acids, vitamins, or minerals. This condition may result from fasting and anorexia nervosa; persistent vomiting (as in bulimia nervosa) or inability to swallow; impaired digestion and intestinal malabsorption; or chronic illnesses that end in loss of appetite (e.g., cancer, AIDS). Malnutrition also can result from limited food availability, unwise food choices, or overzealous use of dietary supplements. Selected nutrient-deficiency diseases are listed within the table.