Both weight gain and weight loss can be side effects of IBS. Certain foods and lifestyle habits may help manage IBS symptoms and maintain a healthy weight.
What is irritable bowel syndrome?
Irritable bowel syndrome (IBS) is a condition that causes regular, uncomfortable digestive symptoms. These can include:
- Stomach cramps
- Pain
- Diarrhea
- Constipation
- Bloating
IBS symptoms can range from mild to severe. Unlike conditions like ulcerative colitis or Crohn’s disease—which can damage the digestive tract—IBS doesn’t cause permanent harm.
About 12% of people in the U.S. have IBS, with women and those under 50 being more likely to experience it.
The exact cause of IBS is still unknown, but it may involve miscommunication between the brain and gut, affecting digestion and bowel movements. Since IBS can influence food tolerance, it may also lead to weight changes.
Can IBS cause weight gain?
IBS can lead to weight loss or gain in some people. Severe cramping and pain might make some eat fewer calories than usual, while others may rely on higher-calorie foods that don’t trigger symptoms.
Some research suggests a possible link between obesity and IBS, though the reason isn’t fully understood. It could relate to differences in diet, fat metabolism, or absorption.
While IBS symptoms can be unpredictable, certain steps—like eating a fiber-rich, balanced diet—may help maintain a stable weight.
Unexplained weight loss with IBS
Weight loss isn’t a typical IBS symptom. If you’re losing weight without trying, it could signal another condition, such as ulcerative colitis or Crohn’s disease (both types of inflammatory bowel disease).
That said, restrictive diets for managing IBS can lead to weight loss. If you notice unexpected weight loss, blood in your stool, or symptoms disrupting your sleep, see a doctor.
How to manage your weight with IBS
Working with a nutritionist can be helpful, whether you’re trying to gain or lose weight. They can guide you in avoiding trigger foods while ensuring proper nutrition.
Exercise might also benefit people with IBS, according to some studies. Staying active can help with both symptom management and weight control.
What can you eat with IBS?
Generally, eating more fiber and avoiding gluten may ease IBS symptoms. Some people worry fiber causes gas, but it can actually help with constipation by softening stools.
Soluble fiber (found in fruits, beans, and oats) is especially helpful. To avoid gas, increase fiber slowly—aim for 2–3 grams more per day while drinking plenty of water. Adults should get 22–34 grams of fiber daily.
Foods that may worsen IBS symptoms for some people include:
- Alcohol
- Caffeine
- Dairy
- Spicy foods
- High-fat foods
- Gluten-containing foods (like wheat and rye)
Keeping a food journal can help identify triggers.
The low FODMAP diet for IBS
A low FODMAP diet may help manage IBS symptoms and weight. FODMAPs (fermentable carbs) are harder to digest and can worsen symptoms. Research shows this diet may improve IBS, but long-term effects need more study.
High-FODMAP foods to limit:
- Fructans (wheat, onion, garlic)
- Fructose (honey, high-fructose corn syrup, apples)
- Lactose (dairy)
- Oligosaccharides (beans, asparagus, artichokes)
- Polyols (sorbitol, other sweeteners)
Low-FODMAP alternatives:
- Fruits: Bananas, blueberries, grapes, oranges, strawberries
- Lactose-free dairy
- Lean proteins: Chicken, eggs, fish, turkey
- Vegetables: Carrots, celery, green beans, lettuce, eggplant
- Sweeteners: Aspartame, cane sugar, maple syrup
The diet involves cutting high-FODMAP foods, then gradually reintroducing them to test tolerance. A nutritionist can help ensure you’re still eating a balanced diet, as this plan may lead to weight loss.
Takeaway
IBS can contribute to weight changes, but lifestyle adjustments—like diet and exercise—can help manage symptoms and maintain a healthy weight.
If dietary changes don’t improve your symptoms, talk to your doctor about other treatments or possible causes of weight fluctuations.