Malnutrition and Weight Loss

The impact of malnutrition

Malnutrition – lack of proper nutrition – is a major challenge with IBD. It is the main cause of chronic weight loss. Malnutrition affects about 65% to 75% of people with Crohn’s disease and 18% to 62% of those with ulcerative colitis.

IBD patients are often underweight, with nutritional deficiencies and changes in their body fat composition, muscle mass, and bone mineral density (which puts them at risk of fractures). They generally have low energy, general fatigue, and weakness.

Malnutrition can lead to anemia: low red blood cells in the blood. This can cause fatigue and other problems. ​Malnutrition also makes it difficult to bounce back from an illness.

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Causes of malnutrition in IBD

The main reasons for malnutrition include inflammation, low nutrient intake, medications, and malabsorption (poor absorption of nutrients in the small intestine). For example, your small intestine might have problems absorbing nutrients. Your large intestine might have difficulty absorbing water and electrolytes.

The most common micronutrient deficiencies in IBD are iron, calcium, selenium, zinc, and magnesium. Vitamin deficiencies include all vitamins, especially B12, folic acid, and vitamins A, D, and K.

IBD symptoms such as diarrhea, abdominal pain, nausea, and rectal bleeding can lead to malnutrition:

  • Diarrhea can cause dehydration, where your body does not get enough fluids, nutrients, and electrolytes. Diarrhea can also lead to weight loss.
  • Frequent bowel movements may make you want to cut back on eating so you do not have to go to the bathroom so often. This puts you at risk for malnourishment.
  • Appetite loss or reduction of food intake due to abdominal pain, nausea, or other reasons may make it hard for you to eat enough calories and nutrients. 
  • Rectal bleeding can lead to iron deficiency and anemia.

Typical causes of malnutrition include:

  • Decreased food intake: from nausea, abdominal pain, vomiting, diarrhea, hospitalization, or prolonged restrictive diets
  • Increased use of energy due to inflammation
  • Nutrient loss due to ulcers or diarrhea
  • Malabsorption (poor absorption of nutrients)  
  • Medications, such as glucocorticoids or cholestyramine

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Preventing malnutrition

To help prevent and manage malnutrition:

  • Get tested for vitamin and mineral deficiencies so they can be addressed with supplements. Your healthcare practitioner may conduct blood tests to determine deficiencies. 
  • Avoid foods that make your symptoms worse, since that can lead to not eating enough. Tracking your food and drink intake can help to identify your trigger foods.
  • Talk to your dietitian to determine a meal plan that works for you. If you do not have a dietitian, ask your healthcare provider or IBD specialist for a referral.

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