How Does Ulcerative Colitis Affect Your Weight?

Medically Reviewed by Sabrina Felson, MD on June 05, 2022

The inflammation, diarrhea, and pain that ulcerative colitis (UC) cause commonly lead to weight loss. But sometimes, people gain weight with UC – either because of its symptoms or because of medicines used to treat it.

Either weight loss or gain can complicate your efforts to manage your condition and lead to additional health issues.

Ulcerative Colitis and Weight Gain

When you have UC, your symptoms can make it harder to exercise or eat a nutritious diet. Yet being active and eating as well as possible can help you avoid complications from UC.

High-fiber foods like fruits and vegetables can bring on symptoms like pain, nausea, or bloating for people with UC. So you may be tempted to avoid fresh foods in favor of higher-calorie, more processed items. What’s more, coping with an intestinal condition like UC can make you more likely to skip meals, restrict what you eat, or binge eat. These unhealthy eating patterns may result in weight gain.

To better manage your symptoms and keep your weight stable:

  • Eat several small meals a day instead of a few large ones
  • Drink lots of water
  • Drink slowly and avoid using straws, which can cause you to gulp and lead to gas and bloating
  • Use healthy cooking methods – boil, grill, steam, or poach your food
  • Keep track of what you eat and drink and whether you have UC symptoms afterward

You may find exercise challenging due to frequent trips to the bathroom, as well as the pain and fatigue UC can cause. Sometimes, you might not feel well enough mentally to motivate yourself to work out. But exercise benefits your emotional and physical health.

Don’t push yourself when you’re having a flare-up. But even when you’re not feeling your best, you can benefit from less strenuous types of exercise like:

  • Walking
  • Biking
  • Swimming
  • Yoga
  • Elliptical and rowing machines

Consult your doctor about what foods and exercise are right for you, especially if you’ve recently had surgery.

Ulcerative Colitis and Weight Loss

Appetite loss is a challenge for people with UC. Symptoms like pain, nausea, bloating, and diarrhea may make you less likely to want to eat. Fatigue can deter you from preparing food.

You could feel full quickly and stop eating before you’ve taken in enough calories. And maybe you’re anxious about trying new foods for fear they’ll worsen your symptoms.

Some researchers believe the inflammation of UC itself causes weight loss. Inflammation in your intestines is thought to increase a digestive hormone that tells your body you’re full. This could be your body’s way of protecting itself from foods that inflame your gut.

But inflammation means you need more, not fewer, calories to help you heal. Try your best to eat during a flare, even if you don’t feel up to it.

To deal with appetite loss:

  • Eat smaller portions throughout the day, which keeps your blood sugar levels steady and discourages bloating
  • Choose nutritious foods that you like
  • Adjust your food’s temperature if hot or cold meals trigger nausea
  • Drink plenty of fluids

If you struggle with your appetite, tell your doctor. Proper treatment of inflammation could help ease this symptom.

Are You Getting Enough Nutrients?

Because UC affects your ability to take in nutrients and digest food, it could lead to malnutrition. That’s when you don’t get enough of the nutrients you need to nourish your organs and tissues. While malnutrition isn’t common for people with UC, even a slight case can make it harder for you to heal if you get sick.

You might associate weight loss with malnutrition, but people with excess weight can be malnourished, too. That’s especially true if, as with UC, you can’t eat a balanced diet due to your symptoms or have problems digesting nutritious foods.

These UC symptoms could put you at risk for malnutrition:

  • Diarrhea that causes dehydration and a loss of electrolytes, essential minerals that are absorbed in the large intestine
  • Appetite loss due to belly pain
  • Bleeding from your rectum that leads to iron deficiency
  • Frequent bathroom trips, since you might eat less in an effort to avoid them

Restricting your diet because of UC can also interfere with nutrition. But so can eating foods that trigger your symptoms, since those symptoms may make you want to eat less.

To make sure you don’t become malnourished:

  • Your doctor can test your vitamin and mineral levels so you can take supplements if you need them.
  • A dietitian can help you develop an eating plan designed around your food limitations and UC triggers.

Medications and Weight

Side effects from some of the drugs used to treat UC can affect your weight, too. Some cause symptoms that contribute to weight loss, like stomach pain, nausea, and vomiting. For others, including corticosteroids like prednisone and budesonide, weight gain may be a side effect.

Weight gain is common with corticosteroids, and can result from increased appetite and/or fluid retention. The longer you take them, the more likely you are to gain weight.

Weight gain has also been reported as a side effect of a type of biologic drug called an anti-tumor necrosis factor agent drug, or anti-TNF. These medicines, such as certolizumab pegol (Cimzia), target proteins in your body that are involved in inflammation.

While some studies have found that anti-TNFs might cause weight gain in people with UC, that’s not necessarily a bad thing. It could be because people with UC feel better when taking the medicine and are able to eat more. We need more research into this potential side effect.

Tell your doctor if you think your medication is causing weight gain or other side effects. They may be able to adjust your dose or prescribe a different medicine.

Ostomy Surgery and Weight Gain

UC patients who have a stoma, an opening surgically created to divert waste from the intestine, often gain weight after the operation. The reasons for this include:

  • You can tolerate foods that were once off-limits
  • You’re better able to absorb nutrients
  • You may eat more starchy foods because they make the stoma output easier to deal with

But weight gain can put you at higher risk for a hernia and other health issues like diabetes or heart disease. So be aware of what you’re eating (a food journal can help), and choose healthy foods like fruits and veggies and lean protein when possible.

Show Sources

SOURCES: “Weight Gain following Stoma Formation.”

Crohn’s & Colitis Canada: “Complications and Extraintestinal Manifestations: Malnutrition and Weight Loss,” “Loss of Appetite”

Crohn’s & Colitis Foundation: “Exercise,” “Fact Sheet: Biologics,” “Malnutrition and IBD,” “What Should I Eat?” “Understanding IBD Medications and Side Effects.”

Inflammatory Bowel Diseases: “Understanding the Cause of Weight Gain in Patients With IBD on Anti-TNF Medication.”

Journal of the American Medical Association: “Stomas.”

Johns Hopkins Medicine: “Malnutrition.”

Mayo Clinic: “Ulcerative Colitis,” “How Obesity Affects IBD Management and Patient Outcomes: Q&A with Amanda M Johnson, M.D.”

Cell Metabolism: “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain.”

Nutrients: “The Gut-Brain Axis and Its Role in Controlling Eating Behavior in Intestinal Inflammation.”

World Journal of Gastroenterology: “Prevalence and Associated Factors of Obesity in Inflammatory Bowel Disease: A Case-Control Study.”

UCSF Health: “ILD Nutrition Manual: Prednisone and Weight Gain.”

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