Crohn’s disease can cause weight loss and make maintaining weight more difficult. Keeping a food journey, making dietary changes, and working with a nutritionist are some ways to help prevent further weight loss.

Crohn’s disease is a form of inflammatory bowel disease (IBD). It causes several gastrointestinal symptoms that can include nausea, vomiting, and abdominal pain and cramping.

Many people also find that certain foods can worsen symptoms, which may lead to self-restrictive diets.

These factors, along with certain medication use, can contribute to weight loss.

This article explores the prevalence of weight loss and Crohn’s disease, reasons for potential weight loss, the role of obesity in Crohn’s disease, and tips for maintaining weight.

Weight loss due to Crohn’s disease often occurs, particularly during active phases or flares.

In an older study from 2014, researchers noted that about 57% of people reported significant weight loss at the time of diagnosis.

A 2020 review of studies noted that weight loss may vary.

The researchers stated that previous studies reported 70–80% of inpatient people living with IBD experience weight loss. IBD includes both Crohn’s disease and ulcerative colitis, so this number does not reflect people with Crohn’s disease specifically.

The researchers also noted that 20–40% of people living with Crohn’s disease who receive care in an outpatient facility report weight loss.

They also reported that malnutrition occurs frequently in IBD but that it appears more commonly in people living with Crohn’s disease.

Crohn’s disease can cause weight loss in several ways, such as:

  • malnutrition
  • reduced appetite
  • loss of nutrients
  • food intolerances
  • medication side effects

Malnutrition commonly occurs in people living with Crohn’s disease. According to a 2020 study, about 20–80% of people living with IBD experience malnutrition. It can occur due to poor absorption of nutrients (malabsorption), limited diet, and eating less.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that what a person eats can affect their symptoms. Therefore, people living with Crohn’s disease often avoid certain foods.

A person should discuss diet changes with a doctor or nutritionist. They can work with an individual to develop an eating plan to help them avoid unwanted weight loss and prevent malnutrition.

People living with Crohn’s disease may lose nutrients through blood loss, vomiting, or diarrhea. This can cause both weight loss and malnutrition.

These symptoms may also contribute to a person experiencing a reduced appetite, which can result in eating less.

Medications to treat Crohn’s disease can cause different side effects. Some drugs, such as corticosteroids, can lead to weight gain.

However, other medications, such as aminosalicylates or immunomodulators, can cause nausea, vomiting, or abdominal pain, which can result in weight loss.

A person who experiences weight loss due to Crohn’s disease may be able to take steps to help maintain their current weight.

One example is keeping a food journal. An individual can record the foods they eat and how they make them feel or how they affect their symptoms.

This process can help someone determine what foods work for them. It can also allow them to provide useful information to their doctors on how foods affect them.

They can then build a dietary plan around foods that work for them, which may help them maintain or gain weight.

The NIDDK suggests that a person with Crohn’s disease can help manage symptoms and maintain a healthy diet by:

  • eating smaller meals more frequently
  • avoiding fizzy drinks
  • drinking more liquid throughout the day
  • avoiding high fiber foods, such as popcorn and nuts

In some cases, a doctor may recommend a higher-calorie diet. This may help a person maintain their current weight at diagnosis or regain lost weight in some cases.

Evidence suggests that people with obesity may have an increased risk of developing Crohn’s disease.

In a 2022 analysis of five cohort studies, researchers found that people with obesity have a higher risk of developing Crohn’s disease later in life compared with people without obesity. They also noted that obesity is a risk factor for Crohn’s disease but not ulcerative colitis.

Another study from 2017 notes that approximately 20–40% of people living with IBD also have obesity. The study explored how obesity affected IBD severity and treatment.

The researchers stated that additional research is still necessary across all aspects of obesity and IBD. They also noted that having obesity did not necessarily increase Crohn’s disease activity or severity nor increase the risk of complications.

They did suggest that certain treatments, such as biologics, may be less effective when a person lives with obesity. However, this assumption is largely around how biologics respond in other autoimmune disorders.

Crohn’s disease is associated with weight loss. Weight loss may occur due to inadequate nutrition as a result of malabsorption, loss of nutrients, or not eating enough food. It may also occur as a side effect of medication or a response to symptoms such as abdominal pain, nausea, or vomiting.

A person with obesity may have an increased risk of developing Crohn’s disease later in life. However, it is not clear how living with obesity affects condition progression or treatment.

When a person with Crohn’s disease is losing weight, there are steps they can take to maintain their weight. This can include keeping a food journal, making dietary changes, or working with a nutritionist to develop a dietary plan.