Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD). It causes inflammation and sores in the intestines, which is where your body absorbs most of its nutrients from food.

Certain factors can prevent you from absorbing enough nutrients, fluid, and electrolytes. These factors include inflammation in your gastrointestinal (GI) tract and symptoms like diarrhea and abdominal pain. Weight loss, weakness, and muscle loss are signs that your body isn’t getting the nutrition it needs.

A well-balanced diet is an important part of managing UC. Eating too few nutrient-dense foods could put you at risk of malnutrition. Too little nutrition can leave you feeling tired and make it difficult for your body to heal.

Managing your UC and working with your doctor and a dietitian can help you maintain weight and feel better during treatment.

It can. Weight loss is a common symptom of UC, especially when the condition isn’t managed. You may lose weight for a few reasons.

Symptoms like nausea and abdominal pain can lower your appetite. Diarrhea and certain drugs you take to manage IBD can make it harder for your body to absorb nutrients from foods. And inflammation makes your body burn calories faster.

IBD causes weight loss for a few reasons:

  • You have diarrhea. During an active symptom flare, you can have six or more loose bowel movements per day. Frequent diarrhea strips your body of nutrients and can lead to weight loss. Some people with IBD eat less to avoid visiting the bathroom so often.
  • You feel too sick to eat. It’s difficult to eat well with symptoms like nausea and abdominal pain. When you have no appetite, you may eat fewer of the calories and nutrients that you need to maintain your weight.
  • You have inflammation. During flares, there’s more inflammation in your colon, leading to severe symptoms such as diarrhea and decreased appetite. This may lead to weight loss.
  • You experience chronic inflammation. A higher demand for protein is often the result of long-term (chronic) inflammation. When this happens, your body may start to break down muscle and other fat-free areas of mass. The decrease in muscle mass can cause you to lose weight.
  • Your doctor has put you on a liquid diet. Inflammation can leave areas of scar tissue called strictures in your intestines. You may need to stick to a liquid diet until the inflammation goes down and your intestine heals.

Doctors do not usually recommend any particular diet for people with UC. The idea is to eat foods that give you enough calories plus a balance of protein, healthy fats, vitamins, and minerals. Work with a dietitian (if you have access to one) to find a meal plan you can tolerate — and that you enjoy.

Certain foods can make UC symptoms worse. During flares, you may need to avoid certain hard-to-digest foods and drinks like:

  • fresh fruits with skin and seeds
  • raw vegetables
  • dairy, such as milk and cheese
  • nuts
  • whole grains
  • sugary foods, such as candy and soda
  • alcohol (if applicable)

But you don’t need to always cut all these items out of your diet.

Instead, you can figure out which foods bother you with the help of a food diary. Write down everything you eat and drink, and take note of when your symptoms flare up or worsen. Share this diary with your doctor and dietitian. Together, you can come up with a plan that ensures you’re eating balanced meals.

After a flare, you can slowly add foods back into your diet. You may want to try increasing your calorie and protein intake to make up for what you lost.

Here are a few other tips to help you gain weight:

  • Eat four to six small meals during the day to increase your daily calorie intake. Smaller meals and snacks are sometimes easier to tolerate than three large meals.
  • Add more protein from foods like fish, eggs, tofu, and chicken.
  • Try to eat more. If you’re eating foods that agree with you and you don’t feel full, go ahead and have seconds. More food equals more calories.
  • Stock your pantry and fridge with foods you like and that are easy for you to eat.
  • Ask your doctor whether you need to take a nutritional supplement if you’re not getting enough nutrients from foods alone.

Finally, talk with your doctor about UC treatments. Medications can help manage inflammation and ease the symptoms that prevent you from eating and gaining weight.

The life expectancy of people with UC has improved over the years thanks to new treatments. People with this condition can expect to live full and happy lives.

Some research has found small differences in life expectancy. In a study from 2020, females with IBD lived 6–8 fewer years, while males lived 5–6 fewer years, in comparison with people without IBD. That doesn’t mean your life will be shorter than the typical lifespan of a person without UC and in good health — these are just averages.

Keep in mind that there are ways to help improve your outlook. One is to see a doctor who’s experienced in treating UC. Getting the right treatment plan can help improve both the length and quality of your life.

Living with UC and the medications you take to manage it can prevent your body from getting the nutrients it needs to stay healthy and heal. During flares, you might not absorb the nutrients you’re putting into your body.

Work with your doctor and a dietitian to create a diet that gives you the right balance of nutrients. Try different foods until you find ones that you can both enjoy and tolerate.