Malnutrition: What You Need to Know

Malnutrition happens when the body does not get enough food or the right amount or balance of nutrients it needs to function properly. It may be caused by overnutrition or undernutrition. An inadequate diet or certain health conditions can cause malnutrition due to undernutrition.

Malnutrition can lead to serious health consequences if not treated and can be life-threatening in some cases. This article describes the different types of malnutrition, as well as its causes, symptoms, diagnosis, treatment, and prevention.

Types of Malnutrition

Malnutrition is an imbalance, deficiency, or excess of energy or nutrients in the body. Types of malnutrition depend on the cause and include undernutrition and overnutrition.

Undernutrition

This type of malnutrition generally results when the body does not get enough calories, protein, or micronutrients (vitamins and minerals).

Undernutrition includes four broad subforms, which are:

• Wasting (low weight for height)
• Stunting (low height for age)
• Underweight (low weight for age)
• Deficiencies in micronutrients 
  

Overnutrition

This type of nutrition results from excessive consumption of nutrients, such as calories, fat, protein, and/or micronutrients. Overnutrition can lead to overweight or obesity. It is possible to be overweight or have obesity and still not get enough micronutrients.

What Causes Malnutrition?

Causes of malnutrition include not having enough food to eat, frequent illnesses, and certain medical conditions and disorders.

Insufficient Food Intake and Poor Diet Quality

Not eating enough or poor diet quality is often the first thing people think about when it comes to malnutrition.

Among populations at risk, poor maternal health and nutrition and inappropriate infant and young child feeding can result in malnutrition. Not getting enough to eat, whether due to living in poverty or not having access to healthy food, is a global problem.

Poor diet quality doesn’t only lead to undernutrition, but can result in overnutrition, as well. Individuals who consume foods and drinks that are full of empty calories (high in calories, low in nutrients) and engage in less physical activity are more likely to develop overnutrition.

Medical Conditions and Digestive Disorders

Malnutrition may be seen in the following types of conditions:

• Medical conditions that deplete calories: Conditions such as chronic diarrhea or cancer can cause wasting (low weight for height).
• Malabsorption and digestive disorders: Conditions such as inflammatory bowel disease (IBD, including Crohn's disease and ulcerative colitis) or pancreatic insufficiency can cause poor nutrient absorption. Even with a normal caloric intake and eating healthy foods, the body might not be able to properly digest and use the nutrients.
• Alcohol use disorder: Excessive alcohol intake can lead to insufficient amounts of calories, protein, and other nutrients the body needs to properly function, resulting in malnutrition.
• Mental health conditions: Depression and other mental health conditions, including the eating disorders anorexia nervosa or bulimia nervosa, can increase the risk of malnutrition. One study in Bangladesh found that the prevalence of depression was 3 times higher in older adults with a poor diet compared to those who were well-nourished.

Socioeconomic Factors

Poor socioeconomic factors, such as little or no education, unemployment, low income, and food or housing insecurity, can all affect the nutritional status of both children and adults. These factors include:

• Low food intake: Living with food insecurity and not eating enough is linked to the risk of malnutrition. When the body does not get enough protein, energy, and nutrients, it can result in weight loss, lack of growth in children, and nutritional deficiencies and imbalances.
• Social and mobility problems: Older adults who are frail, lack muscle strength, or have poor mobility are at increased risk for malnutrition. Mobility problems can impair food preparation skills, while lack of regular social engagement can increase the risk of depression and low appetite.
  
  

Risk Factors for Malnutrition

Malnutrition is a global problem, with every country in the world being affected by one or more forms of malnutrition.

The World Health Organization (WHO) estimates that by 2022 there were over 2.5 billion adults and 37 million children who were overweight or had obesity, and 390 million adults and 194 million children who were undernourished.

Risk factors for malnutrition include:

• Poverty or poor socioeconomic factors
• Older adults, especially those with disabilities or those who live alone
  
• Increased nutritional needs, particularly in children and pregnant or lactating people
  
• Living in underdeveloped countries or regions with poor access to food
  
• Having a medical condition or disease that affects nutrient absorption
  

Malnutrition Symptoms

Signs and symptoms of malnutrition can vary, depending on the type and/or cause. For most types of malnutrition, early signs can be difficult to spot. 

Symptoms of malnutrition include:

• Unintentional weight loss
• Faltering growth and development
• Overweight or obesity (overnutrition)
• Fatigue, weakness, and listlessness
• Poor immune function, causing frequent illness or infection
• Skin rashes, skin that bruises easily, or changes in skin color
• Bleeding gums or other oral health problems
• Changes in the senses of taste, smell, or sight
• Mood changes, anxiety
• Soft or tender bones
• Thin hair or hair loss

Symptoms in Children

Symptoms of malnutrition may present differently in children than adults. In particular, children may experience:

• Lack of growth or weight gain at the expected rate (stunted or faltering growth)
• Changes in mood and behavior, such as being unusually irritable, slow, or anxious
• Delayed intellectual development and behaviors
• Decreased energy and tiring more easily than other children

How Is Malnutrition Diagnosed?

To diagnose malnutrition, a healthcare provider usually begins by obtaining a detailed medical and dietary history. They will also perform a physical examination, examining overall appearance, behavior, body weight, body fat distribution, and organ function. 

Blood or urine tests may be ordered to determine the amount of certain nutrients and waste products in the body. In some cases, X-rays are performed to determine bone density and to detect any heart and lung damage or gastrointestinal (GI) issues.

How Is Malnutrition Treated?

The main goal of malnutrition treatment is to replenish the body with adequate nutrition. Treatment plans are unique to each individual and will vary depending on the underlying cause.

Having a registered dietitian on your healthcare team can help you identify ways to get adequate nutrition from your diet to meet your needs.

If an individual cannot eat by mouth, they may need nutrients delivered through a tube inserted into the GI tract or intravenously (IV).

Specific micronutrient deficiencies are treated by replacing those nutrients. Replacement is usually with supplementation, either by mouth from capsules, tablets, liquid drops, or syrups or via feeding tube or injection.

If the malnutrition is severe, it’s important to follow the care plan set out by your healthcare team to avoid refeeding syndrome. This potentially fatal condition can occur when refeeding is too quickly initiated after a period of severe undernutrition.

If a malnourished individual can eat and drink, eating a more balanced and nutritious diet is the first step in replenishing nutrients. Consuming more calories and protein is important, which may mean including snacks between meals.

They may need to focus on including foods and beverages that are fortified or have certain nutrients added. Nutritional supplements may be needed to help meet daily nutrition goals.

If malnutrition is due to another underlying medical condition, that must first be addressed and treated to help resolve the malnutrition.

What to Eat If You’re Malnourished

People with undernutrition most likely need to increase their calorie and protein intake. Including foods high in calories, such as those with healthy fats can help you meet daily caloric goals.

High-fat, high-calorie foods include:

• Nuts and nut butters
• Seeds
• Avocados
• Olives
• Meat
• Fatty fish
• Whole-fat milk
• Yogurt and cottage cheese
• Coconut milk
• Olive, avocado, or vegetable oils

Good sources of protein include:

• Meat
• Poultry
• Fish and seafood
• Nuts and nut butter
• Seeds
• Legumes (beans, lentils, and peas)
• Eggs
• Milk
• Greek yogurt
• Cottage cheese

Protein powders and drinks may also be good options for increasing protein intake throughout the day.

How to Prevent Malnutrition

Addressing the root causes can help prevent malnutrition. Government agencies, schools, and independent organizations can all help with malnutrition prevention. Addressing food insecurity and increasing education and awareness of malnutrition are important steps in helping to prevent malnutrition.

Studies suggest that some of the most effective ways to address and prevent malnutrition include vitamin and mineral supplements, food supplementation, and providing nutrition education to at-risk populations.

Including a variety of nutritious foods that contain enough carbohydrates, proteins, fats, fiber, vitamins, and minerals can help in preventing malnutrition. Promoting healthy eating habits and encouraging regular physical activity for both children and adults can help avoid overnutrition in those at risk.

Complications and Long-Term Effects of Malnutrition

Though malnutrition is treatable, complications and long-term effects can occur. Malnutrition impacts physical and mental health. Depending on the severity and length of the malnutrition, there may be effects on growth and cognitive development.

Malnutrition can increase the risk of chronic diseases, such as cardiovascular disease, certain cancers, and diabetes.

Some deficiencies can trigger specific health problems, such as the following.

Vision Problems

Night blindness is one of the first signs of vitamin A deficiency. When it becomes more severe, vitamin A deficiency can lead to blindness. According to the WHO, around 250,000 to 500,000 vitamin A–deficient children lose their sight every year, with half of them dying within one year of becoming blind.

Scurvy

Acute (short-term) vitamin C deficiency leads to a condition called scurvy, with symptoms appearing within one month of little or no vitamin C intake. Symptoms include:

• Fatigue
• Malaise (a general unwell feeling)
• Inflamed or bleeding gums
• Small, round spots on the skin
• Easily bruising
• Purple skin rashes
• Joint pain
• Poor wound healing
• Corkscrew hairs
  

Marasmus

Marasmus is severe protein-energy undernutrition, causing an infant's or child's weight to be significantly low for their age. It results from an overall lack of calories from fat, protein, and carbohydrates. Loss of fat tissue and muscle mass occurs, and individuals with marasmus are visibly emaciated and severely underweight.

Signs and symptoms include:

• Severe weight loss
• Prominent bones
• Stunted growth
• Dry skin, hair, and nails
• Fatigue and lethargy
• Dehydration
• Slow heart rate
• Low body temperature
• Anemia (low numbers of healthy red blood cells)
• Softening of bones
• Electrolyte imbalances

Obesity

Undernutrition and obesity can occur at the same time. Consuming empty-calorie foods and beverages (those with lots of calories but little additional nutritional benefit) as the main source of nutrition, along with little to no physical activity, can lead to micronutrient deficiencies while also causing weight gain.

Inflammation and excess fat tissue may be present throughout the body. Obesity increases the risk of other noncommunicable diseases, such as:

• Diabetes
• High blood pressure (hypertension)
• Certain cancers
• Osteoarthritis
• Cholesterol disorders
  

When to Contact a Healthcare Provider

Signs and symptoms of malnutrition may be difficult to spot, especially early on. However, if you notice any of the signs or symptoms below, contact a healthcare provider:

• Unusual or unintentional weight loss
• Changes in appetite
• Difficulty chewing or swallowing
• Fatigue or lethargy
• Faintness
• Wounds that are slow to heal
• Prolonged or chronic diarrhea

Summary

Malnutrition occurs when the body does not get enough food or the right amount or balance of nutrients it needs to function properly. It may be from overnutrition or undernutrition. Causes may include inadequate or poor diet, social or mobility problems in older people, alcohol use disorder,  or certain digestive or malabsorption health conditions. 

Risk factors for malnutrition include poor socioeconomic status, limited access to nutritious foods, having increased nutritional needs, older adults living alone or who have mobility issues, and having a medical condition that affects nutrient absorption.

Signs and symptoms of malnutrition include unintentional weight loss, stunted growth and development, decreased immune function, skin problems, hair loss or thinning hair, fatigue, and mood or behavior changes. 

Malnutrition can lead to serious health consequences if not treated, and in some cases can be life-threatening. Treatment often includes replenishing calories and nutrients and correcting any micronutrient deficiencies.