Does having IBS affect my weight?

Published on 21 December 2022

IBS can be a painful and lifelong condition, but it is manageable, and a low FODMAP diet may be the answer.

Irritable bowel syndrome (IBS) is a condition of the digestive system that can affect one’s quality of life. The symptoms are quite varied, and common ones include bloating, trapped wind, diarrhoea, constipation, and stomach pain. Some individuals may also experience tiredness, poor appetite or a headache. 

Is IBS curable?

Unfortunately, experts remain unclear as to what causes IBS, and there is no one specific treatment or cure for the condition. However, most patients with IBS usually associate their symptoms with certain foods that they have eaten. Therefore, finding out what foods trigger your symptoms and removing them from your diet can be an effective way to manage the condition.

IBS and weight loss or gain

There is a common misconception that IBS causes weight loss. “IBS does not cause weight loss directly, but weight changes often occur in response to certain dietary or lifestyle modifications that a person makes to manage their symptoms,” Ms Lynette Goh, Principal Dietitian, National University Polyclinics (NUP), explained.

For example, some people might experience abdominal cramping to the point that it causes them to reduce their food intake, for fear of triggering IBS. Others may avoid certain foods, or cut down on the amount they eat, resulting in a lower than usual calorie intake.

Expert tips to manage diet and symptoms 

If you find yourself struggling with your weight due to IBS, Ms Ng Su Yi, Senior Dietitian, NUP suggests the following ways to help manage the problem.

Have small, regular meals
Skipping meals may cause you to miss out on nutrients that your body needs. If you are unable to tolerate three full meals, try having five to six small meals and snacks throughout the day instead.

Cut down on fat and oil
This may help to reduce the severity of the symptoms. It is best to avoid processed meat, fatty meat, fried foods and foods prepared with a lot of oil or fat. Instead, eat lean meat, fish, and poultry without skin. Do not add extra gravy to your food. For bread, choose healthy spreads such as soft margarine and nut butters. 

Fibre is necessary
It is best to adjust the amount of fibre you take according to your symptoms. If you have constipation, try to include foods high in fibre. Conversely, avoid high-fibre foods if you have diarrhoea. High-fibre foods include fruit, vegetables, whole-grain bread, oats, brown rice, seeds and nuts.

Water, water, water
Drink at least eight cups of water daily. Drinking enough water can help prevent constipation and prevent dehydration, which is especially important if you have diarrhoea. 

Preventing gas and bloating
Foods that increase gas and bloating include broccoli, brussel sprouts, cabbage, cauliflower, corn, leeks, onions, beans and peas. Avoid eating these if possible. 

Difficult foods
Some people will find that they are unable to tolerate foods or beverages which are acidic, spicy, caffeinated, carbonated, or with mint, so it is best to cut down on these items.

Include probiotics in your diet
Probiotics are “good” bacteria that can help to balance the gut. Besides probiotic supplements, probiotics can be found in natural foods such as certain milk drinks, yoghurt and kefir. However, do note that even though probiotics may be useful in improving IBS symptoms, they may not work for everyone.

The low FODMAP diet
Studies have shown that a low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) diet helps manage IBS symptoms.

But, what exactly is a low FODMAP diet, and why is it recommended for IBS symptom management?

FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) are a group of short-chain carbohydrates found in food. They are poorly absorbed and easily fermented in the gut, causing symptoms such as gas production, bloating and diarrhoea. A low FODMAP diet has been found to improve the symptoms related to IBS. 

Eat your fruits and veggies!

As certain fruits and vegetables are high in FODMAP, people with IBS may avoid eating them.  However, fruits and vegetables are good sources of vitamins, minerals and fibre. Instead of avoiding them, individuals with IBS should include fruits and vegetables that are low in FODMAP into their diet.

A carb story

Foods that contain wheat such as noodles and bread are also high in FODMAP. However, they are a big part of our Asian diet, so it can be hard to give them up! In addition, they are a good source of carbohydrates, which not only provide the body with energy, but also certain vitamins and minerals. It is therefore recommended for individuals with IBS to opt for rice-based low FODMAP carbohydrate food as an alternative to carbohydrates that contain wheat.

A note on dairy

According to Ms Goh, most people with IBS cannot tolerate dairy products, such as milk, ice cream or custard. The problem is, if these calcium-rich dairy products are removed completely from one’s diet, patients may not be able to meet their daily calcium requirements. High-calcium soy milk is a good alternative to dairy products. However, not all soy milk is low in FODMAP - this may trigger IBS symptoms, so do look out for soy milk that is low FODMAP certified. Patients can also try lactose-free dairy products, enriched or fortified almond milk, rice milk, or oat milk. 

While IBS is annoying, Ms Ng shared that it is definitely manageable with the right changes to diet. Speak to your healthcare provider for a formal assessment if you are suffering from unknown causes of gastrointestinal symptoms. Your dietitian can also support you in managing your diet so that you don’t place unnecessary restrictions on yourself. A food and symptom diary is another way to help you understand which food are your triggers. 

Click here to find out more or to join us as a dietitian.