Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD). It is an autoimmune condition in which the immune system mistakenly attacks the large intestine, causing inflammation and ulcers inside its inner lining. Weight loss is often associated with UC, but some people with the condition may experience weight gain.

Alongside weight changes, the common symptoms of UC include diarrhea, blood in the stool, pain in the abdomen, abdominal cramping, and rectal bleeding.

Some people may also experience fatigue, fever, nausea, or vomiting.

In this article, we examine the possible causes of weight gain with UC. We also discuss how people with UC can lose weight, if necessary.

A person with ulcerative colitis eating healthy food to help lose weight.Share on Pinterest
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Several factors may cause a person with UC to experience weight gain. A 2016 study reported that 15–40% of people with IBD also have obesity.

UC itself does not necessarily cause weight gain, with researchers stating that there is “no known association” between IBD and obesity. However, many factors relating to UC may cause weight gain, such as certain medications that doctors prescribe to treat the condition.

During a UC flare, people may reach for more convenient and less nutritious foods, resulting in weight gain. Flares may also lead to a person participating in less physical activity, which may contribute to them gaining weight.

Additionally, some evidence suggests possible shared environmental risk factors between IBD and obesity.

Although many people may think of UC as a condition that causes weight loss, it can also contribute to weight gain. There are many reasons for this, including:

A lack of exercise

Some people may find it difficult to motivate themselves to exercise when they are experiencing a flare of symptoms.

Although people with UC should continue exercising regularly, they may find that lower energy levels prevent them from being active. Healthcare professionals can suggest the most suitable forms of exercise to attempt during a flare.


Corticosteroids, such as prednisone, are medications that reduce inflammation.

One possible side effect of prednisone, as well as other corticosteroids, is weight gain. Weight gain may continue even after a person stops taking the medication, and it can be challenging to reverse.

Other medications to treat UC also have links to weight gain, such as anti-tumor necrosis factor-alpha drugs.

No specific food or diet will help everyone who experiences weight gain from UC lose weight. However, the following weight loss tips may help people moderate their weight.

Maintain a healthy diet

People with UC should eat a nutritious, well-balanced diet full of nutritious foods, including:

  • Fruits and vegetables: People should try a variety of fruits and vegetables and remove the peel and seeds if they trigger a flare.
  • Fiber-rich foods: These include whole grains, beans, nuts, oat bran, and barley. These foods are unsuitable for people with an ostomy or intestinal narrowing, and a person should avoid them if a doctor has advised them to follow a low fiber diet.
  • Calcium-rich foods: These foods include milk, yogurt, kefir, lactose-free dairy products, and collard greens.
  • Protein: Lean meats, fish, tofu, nuts, and eggs are good sources of protein.
  • Food with probiotics: People can try including more yogurt, miso, sauerkraut, tempeh, and kimchi in their diet.

When experiencing a flare, a person may tolerate moderate portion sizes of the following foods:

  • low fiber fruits
  • lean protein, such as fish, poultry, soy, and eggs
  • refined grains, such as sourdough, white pasta, potatoes, and oatmeal
  • vegetables that are fully cooked and do not contain seeds or skin

Specific diets that a person may wish to discuss with a healthcare professional include:

  • the Mediterranean diet, also known as the anti-inflammatory diet or IBD-AID
  • the Paleolithic diet
  • omega-3 enriched diets
  • semi-vegetarian diets
  • fasting diets

Some people with UC may experience malnutrition due to their body not absorbing all the vitamins and minerals that they consume. These individuals should discuss any significant changes in their diet with a healthcare professional.

Stock up on nutritious, convenient foods

People experiencing a UC flare may eat unhealthy “junk” foods for convenience rather than seeking out healthier alternatives.

Stocking cupboards and the refrigerator with quick, nutritious foods that are enjoyable can help people make food choices that are better for their health and prevent them from snacking on nonnutritious foods.

Avoid trigger foods

Researchers have found that some foods may be more likely than others to cause a person with UC to experience a flare. Some of these foods, such as those high in sugar and fat, can also contribute to weight gain.

By reducing their consumption of foods high in sugar and fat, people with UC may prevent weight gain and decrease flares.

Try a gluten-free diet

Some people with IBD find that cutting out gluten helps improve their symptoms. However, no research currently proves this claim. Furthermore, the Crohn’s & Colitis Foundation notes that gluten-free products often contain a higher fat content, contributing to weight gain.

Drink plenty of water

Drinking a glass of water about half an hour before meals can help people feel fuller and eat fewer calories. People who drink water before meals may lose up to 44% more weight than people who do not, according to an older study from 2009.

This habit is also beneficial because it is crucial for people with UC to stay hydrated due to the loss of fluids from diarrhea.

Chew slowly

As well as allowing the brain time to detect satiety, chewing more slowly and thoroughly ensures that the body breaks down food before it reaches the stomach and gastrointestinal (GI) tract.

By chewing slowly, a person is also less likely to introduce air pockets into their GI tract, which can cause gas and discomfort for people with UC.

Exercise regularly

According to the Centers for Disease Control and Prevention (CDC), adults should aim for at least 150 minutes of moderate intensity physical activity or 75 minutes of vigorous intensity physical activity each week to lose weight or maintain a moderate weight.

Going for a short daily walk could help people lose weight and prevent weight gain. Regular physical activity can help improve sleep, memory, and the ability to think and learn.

Other strategies that may help someone lose weight include:

  • Cutting down on alcohol: Drinking alcohol can cause a person to experience symptoms of UC and gain weight. People who drink alcohol may find that reducing their intake is an easy way to cut down the number of calories they consume.
  • Reducing plate size: People can reduce their portion sizes by replacing their dinner plate with a side plate. A small plate gives the illusion of a full plate while decreasing the portion size.
  • Taking steps to improve sleep hygiene: Getting enough sleep can help a person lose weight. Research suggests that low quality sleep is a risk factor for weight gain.

Although people do not usually associate weight gain with UC, it is not uncommon for the condition to have this effect. People with UC may need to monitor their weight to counteract any weight loss or gain due to the condition.

Some people with UC may be unable to lose weight due to their medications. Others may have difficulty getting enough exercise when their symptoms flare up.

If necessary, people with UC can try to lose weight by:

  • eating a nutritious, well-balanced diet
  • ensuring that they have healthy snacks to hand
  • avoiding trigger foods
  • trying a gluten-free diet
  • drinking enough water
  • chewing foods slowly
  • getting regular exercise

Maintaining a moderate weight is key to reducing the risk of developing several other health conditions.