Both undernutrition and overnutrition are forms of malnutrition—a state of inadequate or unbalanced nutrition. Sometimes, undernutrition does not stem from a lack of food overall, but from a lack of specific essential nutrients, known as nutrient deficiency.

UNDERNUTRITION

inadequate nourishment caused by insufficient dietary intake of one or more essential nutrients or poor absorption and/or use of nutrients in the body

OVERNUTRITION

excess intake or imbalance of calories and/or essential nutrients relative to need that results in adverse health effects

MALNUTRITION

a state of undernutrition or overnutrition caused by inadequate, excessive, or unbalanced intake of calories and/or essential nutrients

NUTRIENT DEFICIENCY

a condition resulting from insufficient supply of essential nutrients through dietary inadequacy or impaired absorption or use

Obesity—a condition characterized by excess body fat and often associated with other health problems—is a classic example of overnutrition. It’s a relatively new public health concern—historically, nutrition policy and research has focused on making sure people had enough to eat, so they could meet their nutrient and energy needs. But over the past few decades, policymakers have focused more on the role of diet and nutrition in diseases caused by overconsumption—primarily too many calories, along with too much solid fat (such as animal fats), sugar, and sodium. These are often chronic diseases of slow progression, such as heart disease, and diabetes. Chronic diseases are now, by far, the leading causes of mortality worldwide, and diet plays a specific role in the risk, progression, and treatment of nearly every chronic disease. In addition to providing a lot of calories, the highly processed foods common in our “Westernized” diet are generally low in nutrients such as fiber, potassium, calcium, and vitamin D that reduce the risk of chronic diseases.

OBESITY

a condition characterized by accumulation of excess body fat, generally associated with adverse health effects

CHRONIC DISEASE

diseases that are generally slow in progression and of long duration; e.g., heart disease and diabetes