What is Malnutrition?

Jenna Natwick
Jenna Natwick

| 4 min read

Chances are if you’ve ever watched the news, you’ve heard the word malnutrition. However, many don’t know much about malnutrition and how common it is.
According to the World Health Organization (WHO), approximately 2.4 billion adults are considered malnourished. Malnutrition is an ever-growing issue, so it’s necessary to learn the facts and avoid malnutrition.
Malnutrition doesn’t just mean undernutrition, when you’re not eating enough nutrient-rich food. It can also mean overnutrition.


Undernutrition occurs when you don’t get enough nutrients in your diet. This can happen due to inadequate food or nutrient intake, or an inability to absorb nutrients from food. Undernutrition can be visible, giving an appearance of decreased muscle and fat. However, it may be invisible as well.
There are two forms of undernutrition- macronutrient and micronutrient undernutrition. Macronutrient undernutrition is a deficiency of proteins, carbohydrates and/or fats. These are the nutrients your body needs in the largest amounts. Without them, your body can begin to break down.
Micronutrient undernutrition is a deficiency of vitamins and minerals. These nutrients are needed in smaller amounts than macronutrients, but they are still vital to many of your body’s functions. Going too long without enough of certain micronutrients can have lasting harmful effects on your body.
The populations most frequently affected by undernutrition are:
  • Low-income households
  • Children
  • Chronically ill
  • Elderly


Overnutrition is a recent addition to the WHO's definition of malnutrition. Overnutrition can refer to the effects of being overweight or obese, or the effects of overdosing on micronutrients. 
Like undernutrition, overnutrition also comes in two forms. Macronutrient overnutrition occurs when you have an excess of carbohydrates, proteins or fats. When these macronutrients are consumed in excess, they are stored as fat. In order to store the fat, your fat cells can enlarge or more fat cells are produced. This introduces a host of problems that can have serious health effects.
Micronutrient overnutrition is much less common than macronutrient and cannot occur from diet alone. However, it is important to know the dangers. It is possible that large amounts of vitamins or minerals can lead to an overdose. If you take a large dose of vitamins or minerals, it can have toxic effects. It is recommended that you check with your primary care provider (PCP) about the appropriate dose of supplements.
The populations most affected by overnutrition are:
  • Low-income households
  • Sedentary individuals

Symptoms of malnutrition

The symptoms of malnutrition vary based on the type of malnutrition. According to Cleveland Clinic, if you’re undernourished, your body will not have the amount of energy needed to sustain itself. This can cause the body to break down its tissues for energy. It can also lead the body to shut down its functions. Individuals with macronutrient undernutrition are likely to be micronutrient undernourished as well.
Possible effects of undernutrition are:
  • Increased susceptibility to illness or infection
  • Low heart rate, blood sugar or body temperature
  • Feeling faint or weak
  • Loss of appetite
  • Loss of body fat or muscle
  • Apathy, irritability or inattention
  • Thin arms and legs, with edema in the belly and face
  • Brittle hair, loss of hair or hair pigment
  • Inelastic or dry skin
  • Rashes or lesions on the skin
  • Stunted growth or development in children
Both types of overnutrition can disrupt body functions. Macronutrient overnutrition, specifically, can cause multiple noncommunicable diseases alongside other dangerous health effects.
Possible effects of overnutrition are:
  • Obesity
  • Heart disease
  • Symptoms of metabolic syndrome: high blood pressure or insulin resistance
  • Coronary artery disease
  • Stroke
  • Type 2 diabetes
  • Chronic inflammation from enlarged fat cells
Individuals with macronutrient overnutrition may experience micronutrient undernutrition if they are consuming calorie dense foods that lack vitamins and minerals. This may cause the effects of undernutrition to be less obvious. Symptoms of anemia, such as faintness or weakness, may be an indication of micronutrient undernutrition.

Avoiding malnutrition

To avoid malnutrition, it’s important to know the recommended nutrients for you. According to the National Institutes of Health, there are reference values available for assessing nutrient recommendations. The set of values are known as Dietary Reference Intakes (DRI). The values vary based on sex and age.
To calculate your DRI values, the NIH recommends using this interactive calculator: DRI Calculator for Healthcare Professionals
The best way to prevent malnutrition is eating a well-balanced diet with a variety of nutrients. Talk with a health care provider about your health and your diet about any concerns you may have.
Photo credit: Getty Images

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