IBS and Weight Gain or Loss
Both weight gain and weight loss may be side effects of IBS. Certain foods and lifestyle habits may help you manage IBS symptoms and maintain a moderate weight.
Irritable bowel syndrome (IBS) is a condition that causes uncomfortable gastrointestinal (GI) symptoms on a regular basis. These can include:
Symptoms of IBS can be mild or severe. The difference between IBS and other conditions that cause similar symptoms — such as ulcerative colitis and Crohn’s disease — is that IBS doesn’t cause permanent damage to the digestive tract.
IBS affects around 12% of people in the United States, with women and people under age 50 having a higher chance of experiencing the condition.
Currently, the exact causes of IBS are unknown. The condition could be due to a miscommunication between your brain and your gut that impacts your digestive system and bowel movements. Because IBS can affect the type of foods a person can tolerate, it may lead to weight changes.
IBS can result in weight loss or gain in certain individuals. Some people may experience significant abdominal cramping and pain that may cause them to eat fewer calories than they normally would. Others may stick to certain foods that contain more calories than needed.
Recent research has indicated that there may also be a connection between obesity and IBS. The link isn’t fully understood, but may be related to differences in diet or in fat metabolism or absorption.
You may not always be able to control your symptoms when you have IBS. Still, there are some steps that may help you maintain a moderate weight, including eating a healthful diet that includes fiber.
Unexplained weight loss with IBS
It’s not typical to have weight loss because of IBS. Unexplained weight loss may indicate another disease, like ulcerative colitis or Crohn’s disease, which are types of inflammatory bowel disease.
At the same time, know that following restrictive diets to manage IBS symptoms may result in weight loss.
If you’re losing weight unexpectedly, notice blood in your stool, or your symptoms are disturbing your sleep, it’s important to see a doctor.
Whether you’re seeking to gain or lose weight, working with a nutritionist may be a good idea if you have IBS. They can help you identify and avoid foods that may worsen your symptoms while making sure you’re still getting the nutrients you need.
More studies are needed, but research suggests that exercise may benefit people with IBS as well. Regular physical activity can also help you manage your weight.
In general, eating more fiber and avoiding gluten may help reduce IBS symptoms.
People with IBS may be hesitant to eat fiber-rich foods out of fear that they’ll cause gas and worsen symptoms. However, fiber may decrease constipation by softening stool.
In particular, soluble fiber may help with IBS symptoms. This type of fiber is found in foods including:
It’s best to slowly add fiber to your diet, which helps reduce the likelihood of gas. Aim to add between 2 to 3 grams of fiber per day while drinking plenty of water to minimize symptoms. An ideal daily amount of fiber for adults is between 22 and 34 grams .
You may want to avoid foods that appear to worsen IBS symptoms in some people. These include:
- alcohol
- caffeine
- dairy
- spicy foods
- high fat foods
- foods that contain gluten, like wheat and rye products
Your doctor may also recommend keeping a journal of the foods you eat to see if you can identify ones that tend to worsen your symptoms.
Another option for those looking to maintain a moderate weight and minimize IBS symptoms is a low FODMAP diet. FODMAP stands for fermentable oligo-, di-, mono-saccharides, and polyols.
The carbohydrates found in these foods tend to be more difficult for people with IBS to digest and may worsen symptoms. Research indicates that the low FODMAP diet may improve IBS symptoms, though more studies are needed to examine its long-term health effects.
The diet involves avoiding or limiting foods that are high in FODMAPs, including:
- fructans, found in wheat, onion, and garlic
- fructose, found in honey, high fructose corn syrup, and apples
- lactose from dairy products
- oligosaccharides, found in beans, asparagus, and artichokes
- polyols from sweeteners like sorbitol
Reading nutrition labels carefully and avoiding these foods may help you reduce the likelihood that you’ll experience symptoms related to IBS.
Examples of low FODMAP foods that may be better for people with IBS include:
- fruits like bananas, blueberries, grapes, oranges, grapefruit, and strawberries
- lactose-free dairy
- lean proteins, including chicken, eggs, fish, and turkey
- vegetables like carrots, celery, green beans, lettuce, and eggplant
- sweeteners like aspartame, cane sugar, and maple syrup
Those on a low FODMAP diet may eliminate some higher FODMAP foods and slowly add them back in to determine what foods can be safely eaten. It’s best to work with a nutritionist to make sure you’re eating a balanced diet, as limiting foods for this eating plan may lead to weight loss.
Weight loss or gain may be a side effect of IBS. However, there are lifestyle approaches that can help you reduce your symptoms while maintaining a moderate weight.
If a dietary approach doesn’t help your symptoms, talk with your doctor about additional treatments, as well as other potential causes of changes to your weight.
Last medically reviewed on March 15, 2023
How we reviewed this article:
Austra Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.
- Aasbrenn M, et al. (2017). Prevalence and predictors of irritable bowel syndrome in patients with morbid obesity: A cross-sectional study.
bmcobes.biomedcentral.com/articles/10.1186/s40608-017-0159-z - Bellini M, et al. (2020). Low FODMAP diet: Evidence, doubts, and hopes.
ncbi.nlm.nih.gov/pmc/articles/PMC7019579/ - Cozma-Petruţ A, et al. (2017). Diet in irritable bowel syndrome: What to recommend, not what to forbid to patients!
ncbi.nlm.nih.gov/pmc/articles/PMC5467063/ - Eating, diet, and nutrition for irritable bowel syndrome. (2017).
niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/eating-diet-nutrition - Frieling T, et al. (2019). Tolerability of FODMAP – reduced diet in irritable bowel syndrome – efficacy, adherence, and body weight course.
pubmed.ncbi.nlm.nih.gov/30873577/ - Irritable bowel syndrome. (n.d.).
gi.org/topics/irritable-bowel-syndrome/ - Nanayakkara WS, et al. (2016). Efficacy of the low FODMAP diet for treating irritable bowel syndrome: The evidence to date.
ncbi.nlm.nih.gov/pmc/articles/PMC4918736/ - Patel N, et al. (2022). Irritable bowel syndrome.
ncbi.nlm.nih.gov/books/NBK534810/ - Schoenfeld PS, et al. (2016). Advances in IBS 2016: A review of current and emerging data.
ncbi.nlm.nih.gov/pmc/articles/PMC5210026/ - Zhou C, et al. (2018). Exercise therapy of patients with irritable bowel syndrome: A systematic review of randomized controlled trials.
onlinelibrary.wiley.com/doi/abs/10.1111/nmo.13461
Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.