Is IBS a Cause of Weight Loss or Gain?

Diet Choices, Lifestyle, and Mental Health Play a Role

Weight loss or weight gain are not typical symptoms of irritable bowel syndrome (IBS). While you might want to place the blame on IBS, it's not the condition itself that is causing your fluctuations in weight.

Woman being weighed at the doctor
Science Photo Library / An Hooton / Brand X Pictures / Getty Images

IBS is a condition that impacts your gastrointestinal system, causing pain and bowel symptoms like constipation or diarrhea.

In people with the condition, weight changes may have to do with diet choices and stress about whether foods will cause a flare. For some, IBS symptoms can limit the physical activities that could build a healthy, lean body. Diet advice you see for the general population don't always work for people coping with IBS.

Regardless of which side of the spectrum you're on—losing or gaining too much weight—there are ways to focus your eating habits to enjoy good nutrition and achieve a healthy weight.

IBS and Weight Gain

IBS can contribute to habits that result in gaining extra pounds or making it more difficult to lose excess weight. These include:

Limiting yourself to "safe" foods that aren't necessarily the healthiest: Gluten-free foods that are packed with sugar and unhealthy fats may help you avoid an IBS flare, but they are less nutritious and often have higher calorie counts. Adopting a low-FODMAP diet may help you make healthy food choices and keep your symptoms at bay.

The low-FODMAP diet avoids foods with certain types of sugars, namely fermentable oligosaccharides, disaccharides (like lactose), monosaccharides (like fructose), and polyols (soritol and mannitol). Though it is a restrictive diet, there are still plenty of options to eat well. It is possible to maintain and lose weight on a ​low-FODMAP diet, but you may need to follow a structured plan or consult a dietitian to do it right.

Avoiding exercise: Exercise is important for building muscle and lean body mass and burning calories. Disruptive IBS symptoms can make it difficult to exercise. While there may be some activities, such as running, that set off diarrhea, there are ways to enjoy exercise and physical activity when you have IBS. Talk to your healthcare provider about how you can incorporate exercise into your daily life.

Bloating: IBS symptoms can cause bloating in your abdomen, which would make a person look and feel "heavier." Different food choices and exercise can help reduce bloating.

IBS and Weight Loss

Weight loss is not a symptom of IBS. However, if you're restricting what you eat to avoid symptom flareups, you can lose weight. Limiting your food intake can deprive your body of essential vitamins and minerals, so it's important to maintain a healthy diet even if you have IBS.

Though it's tempting to severely restrict your diet to cope with IBS, a better strategy is to learn what foods your body can best tolerate. If you have IBS and would like to gain weight, some tips include not skipping meals and eating an extra meal each day. You can also eat more of certain foods, such as:

  • Seeds
  • Nuts or nut butter
  • Trail mix
  • Avocados
  • Low-FODMAP fruits, like bananas, blueberries, oranges and strawberries
  • Green smoothies
  • Healthy oils, such a olive, avocado or coconut oil

It is essential that you bring any unexplained weight loss to the attention of your physician. Being underweight and/or malnourished can be a sign of a more serious digestive illness, such as celiac disease or inflammatory bowel disease.

Anxiety and Stress

The uncertainty of IBS—not knowing which foods could cause a flare or when symptoms will appear—can cause anxiety for people living with the condition. If you have gained excess weight, or lost significant weight as a result of living with IBS, this can add to your stress. It can result in a vicious cycle of unhealthy food choices (or even not eating much at all) that can significantly impact your quality of life.

Taking steps to better understand which foods you can tolerate well and talking with your healthcare provider about your weight goals and symptom management is a strong first step to feeling better.

A Word From Verywell

IBS can make weight loss and weight gain more challenging. Many of the recommendations you see for people without IBS are harder to apply to your situation. It can be helpful on either end of the weight loss/weight gain spectrum to ask your healthcare provider for a referral to a registered dietitian to help guide your food choices and devise a plan for you in light of your IBS. If you try following advice on your own and aren't achieving your goals, consider taking that next step.

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2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1.  National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of irritable bowel syndrome.

  2. Anxiety & Depression Association of America. Overcoming irritable bowel syndrome (IBS).

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