What Is Malnutrition?

Empty plate with knife and fork on table.
Jorg Greuel / Getty Images

Malnutrition is the condition of not getting enough or getting too much of a nutrient or nutrients. There are two forms of malnutrition: overnutrition and undernutrition. Both conditions can come with serious health consequences.

Find out the risks associated with different forms of malnutrition and what you can do to prevent nutrient imbalances so that you can stay healthy.


Overnutrition happens when you take in more of a nutrient (or nutrients) than you need every day. While many people think malnutrition means a lack of nutrients, overconsumption is also considered malnutrition because it has negative health consequences.

Energy Overnutrition

Consuming too many calories (or energy) will cause you to gain weight over time unless you increase your physical activity. It doesn't matter if those extra calories come from macronutrients (fat, carbohydrates, or protein), because the body takes whatever it doesn't need and store it as fat.

Energy overnutrition is common in developed countries. Sometimes, people with this type of overnutrition may also experience micronutrient undernutrition if the foods they eat are high in calories but low in micronutrients.

Overnutrition often leads to overweight or obesity, which are risk factors for cardiovascular disease, certain forms of cancer, and type 2 diabetes.

Micronutrient Overnutrition

Micronutrient overnutrition occurs when you consume too much of a certain nutrient. It's possible to get too much of most vitamins or minerals. Usually, this happens when you take megadoses of dietary supplements. Getting too much of any micronutrient from food is rare. 

Micronutrient overnutrition can cause acute poisoning, such as taking too many iron pills at once. It can also be chronic if you take large doses of a particular vitamin (such as vitamin B6) over several weeks or months.

The Institute of Medicine has established tolerable upper limits for most micronutrients, but the best way to avoid this type of overnutrition is to stay away from high doses of dietary supplements unless directed by your healthcare provider.


Undernutrition occurs when you don't get enough of a nutrient (or nutrients) or calories in general. As with overnutrition, there are two types of undernutrition, energy (calories) and micronutrients. Undernutrition can occur when you do not eat enough food, do not eat enough nutritious foods, or have a medical condition that interferes with the absorption of nutrients.

Energy Undernutrition

Energy undernutrition, or protein-energy malnutrition (PEM), is the form of malnutrition that most people associate with the word 'malnutrition.' Energy undernutrition is more common in underdeveloped countries.

Protein-Energy Malnutrition

PEM occurs when people don't get enough energy from food because they don't have enough food, or can't or don't want to eat.

Protein-energy malnutrition can happen in children who are undernourished and suffer from weight loss. They may also experience difficulties with learning and school. Pregnant people with PEM frequently give birth to babies who are also underweight. Certain diseases, such as some types of cancer, can also cause undernutrition. There are two forms of PEM:

  • Starvation (marasmus): Starvation, sometimes called marasmus, is a severe form of malnutrition due to lack of total energy, resulting in poor growth, infertility, and even death. The body breaks down its own tissues to survive, and the body becomes emaciated in appearance.
  • Protein deficiency (kwashiorkor): A lack of protein can cause PEM, even though there is still some carbohydrate or fat in the diet. This condition is called kwashiorkor. People with kwashiorkor have thin arms and legs and bloated abdomens.

Micronutrient Undernutrition

Micronutrient undernutrition means a deficiency in one or more vitamins or minerals. Vitamin or mineral deficiency occurs when the diet is out of balance, and it can happen whether or not calorie intake is adequate.

Iron and calcium are often insufficient in the typical diet. Iron is low in upwards of 25% of people worldwide, especially young children, women, and pregnant people. Research shows that both teenagers and older adults do not get enough calcium through their diet.

In some cases, nutrient deficiency is due to a chronic health condition such as pernicious anemia (which results in a lack of vitamin B12), Crohn's disease, celiac disease, or infection. Symptoms usually don't occur immediately, but arise over time.

Malabsorption occurs when the digestive system can't break down nutrients for proper absorption. This can lead to micronutrient undernutrition. Malabsorption can sometimes be treated with dietary changes, but may require medical treatment.

Signs of Malnutrition

Signs and symptoms associated with malnutrition can vary depending on the type of malnutrition and underlying cause. Some signs of undernutrition include:

  • Weight loss
  • Lowered appetite
  • Fatigue
  • Weakness
  • Frequent illness
  • Reduced concentration
  • Intolerance to cold
  • Poor wound healing, rashes, and dry skin
  • Mood disruptions
  • Bruising
  • Hair thinning

Overnutrition of calories can lead to weight gain, diabetes, high blood pressure, high cholesterol, inflammation, and other symptoms. Signs of overnutrition of vitamins and minerals can depend on the particular nutrient, but some symptoms to look for include:

  • Cloudy urine
  • Increased frequency and amount of urination
  • Heartbeat irregularities
  • Eye irritation or sensitivity to light
  • Cracked, dry lips

If you or a loved one is experiencing this symptoms or others that concern you, discuss them with a healthcare provider for a diagnosis and treatment.

Treating and Preventing Malnutrition

Treating energy overnutrition requires dietary adjustments to reduce overall calories and improve the balance of the diet to include more fruits and vegetables, whole grains, calcium sources, and healthful protein sources with a few good fats.

It also helps to avoid junk foods, which are high in calories but have little nutritional value. Sometimes, medical conditions such as hypothyroidism make it harder to lose excess weight.

Prevent and treat undernutrition by making sure to eat plenty of whole, nutrient-dense foods such as a large variety of fruits and vegetables, whole grains, and lean proteins. You can also take a multivitamin or supplement with a particular nutrient that you may be deficient in. Speak to your doctor to see if this is an appropriate option for you.

Frequently Asked Questions

Who is most prone to overnutrition in the United States?

Children who grow up in low socioeconomic status environments are particularly prone to energy overnutrition. They may lack access to nutrient-dense food and instead consume energy-dense food (high in calories but low in protein, vitamins, and minerals).

Which health issue is associated with malnutrition?

Celiac disease, Crohn's disease, anemia, and infections can lead to malabsorption and cause malnutrition. Sometimes people with depression can undereat or eat poorly, which may lead to malnutrition.

In turn, malnutrition may lead to a loss of muscle mass and function; stress on the heart, lungs, liver, and gastrointestinal tract; weakened immunity; poor wound healing; and psychological effects such as depression and anxiety.

A Word From Verywell

Adequate, balanced nutrition is critical for good health. Most causes of malnutrition can be addressed with a healthy, wholesome diet. If you or a loved one is experiencing symptoms of malnutrition, it’s important to seek medical help.

10 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Fruh SM. Obesity: Risk factors, complications, and strategies for sustainable long-term weight managementJ Am Assoc Nurse Pract. 2017;29(S1):S3-S14. doi:10.1002/2327-6924.12510

  2. National Institutes of Health Office of Dietary Supplements. Iron: Fact sheet for health professionals.

  3. National Institutes of Health Office of Dietary Supplements. Vitamin B6: Fact sheet for health professionals.

  4. McLean E, Cogswell M, Egli I, Wojdyla D, de Benoist B. Worldwide prevalence of anaemia, WHO Vitamin and Mineral Nutrition Information System, 1993-2005Public Health Nutr. 2009;12(4):444-454. doi:10.1017/S1368980008002401

  5. Bailey RL, Dodd KW, Goldman JA, et al. Estimation of total usual calcium and vitamin D intakes in the United StatesJ Nutr. 2010;140(4):817-822. doi:10.3945/jn.109.118539

  6. U.S. National Library of Medicine. Malabsorption syndrome.

  7. John Hopkins Medicine. Malnutrition.

  8. Mount Sinai Hospital. Multiple vitamin overdose information.

  9. Shifler Bowers K, Francis E, Kraschnewski JL. The dual burden of malnutrition in the United States and the role of non-profit organizationsPrev Med Rep. 2018;12:294-297. doi:10.1016/j.pmedr.2018.10.002

  10. Saunders J, Smith T. Malnutrition: causes and consequences. Clin Med. 2010;10(6):624-627. doi:10.7861/clinmedicine.10-6-624

Additional Reading

By Shereen Lehman, MS
Shereen Lehman, MS, is a former writer for Verywell Fit and Reuters Health. She's a healthcare journalist who writes about healthy eating and offers evidence-based advice for regular people.