Can IBS Cause Weight Gain Or Weight Loss?

Can IBS cause weight gain? IBS or irritable bowel syndrome affects about 1 in 20 Americans and can be a very unpredictable disorder, including how it affects weight. Here’s what you should know about IBS and weight gain and weight loss, according to a gut health dietitian. 

Irritable bowel syndrome is an incurable disorder, but proper lifestyle management can make the condition quite manageable. That said, IBS disproportionately affects women, and one of the biggest concerns expressed by my clients with IBS is how it may affect their weight and how they can control it. However, does IBS cause weight gain or weight loss? I’ve taken a deeper dive into both of these to provide more dietitian insight.

IBS and Weight Gain

Weight gain and IBS may be connected, according to some research. There isn't a clear explanation for the connection, but it does not appear that IBS itself causes weight gain. As a result of the physical changes and diet adopted by those who have the condition, weight gain seems to be a secondary effect. Here are some common reasons your IBS symptoms may cause some sneaky weight gain.

1. Bloating

The effect that IBS may have on the speed at which food moves through the digestive tract, the population of gut bacteria, and changes in the structure of the intestines themselves, are possible explanations for the bloating associated with IBS. Foods like FODMAPs, which we’ll discuss later, have also been known to cause bloating in those with IBS. 

However, though bloating is often misinterpreted as weight gain, there is likely no fat loss. Try to observe whether or not the “weight gain” is centered around the stomach. Also, you can try giving the bloating a few days and it’ll likely go away. Fat loss, on the other hand, doesn’t happen that easily.

2. Food Preferences

People with IBS may have a mental list of foods that are "safe." This may be due to the wide range of foods that can cause symptoms from stomach cramps to unpleasant bathroom trips. 

Many fruits and vegetables, though high in fiber and helpful for maintaining weight, may cause symptoms because of the types of sugars they contain (more on that later). So, depending on who you are, the foods you tend to stick to may be high in calories and not very satiating. This means they don’t cause a feeling of fullness for long, and can lead to overeating and weight gain. 

3. Exercise Changes

Many types of exercise, like intense cardio or HIIT that people tend to do to lose weight or maintain it, are also the type that can exacerbate IBS symptoms. The blood flow to and from the digestive system tends to get disrupted during exercise since the body will begin shuttling that blood flow to the muscles. This is usually not a problem, but for people with IBS, the symptoms may cause them to avoid exercising.

4. Stress and Inflammation

Studies have shown that stress can be a major exacerbator of IBS. One consequence of psychological stress along with low grade inflammation in those with IBS is the impact it can have on the microbiome. These changes in gut bacteria can influence weight. 

The microbiome, as well as IBS itself, can lead to changes in mood and even depression. This can lead to stress eating and decreased motivation to exercise, all of which can indirectly promote weight gain.

Does IBS Cause Weight Loss?

IBS and weight loss are not typically associated with each other. If this is something you ever experience or are experiencing now, you should seek medical attention. 

Weight loss is more common in a condition such as IBD (inflammatory bowel disease) which includes ulcerative colitis and Crohn’s disease. Are you unconsciously consuming fewer calories because you are afraid of triggering uncomfortable symptoms? While the weight loss may seem like a cool perk, it may actually indicate that your IBD is causing you to not absorb all of the nutrients from your food. This can result in malnutrition, muscle wasting and other serious conditions.

If you are certain you are eating a healthy amount of calories and still having rapid, unexplained weight loss, contact your healthcare provider to see if you have a more serious condition. 

Can You Lose Weight If You Have IBS?

The good news is that IBS doesn’t have to stop you from losing weight, but it can pose a bit of a challenge. That’s why the best next step is to reach out to a nutrition professional for help. Those with IBS along with some people without a formal IBS diagnosis may be experiencing IBS symptoms due to a FODMAP sensitivity. 

FODMAP stands for:

• Fermentable

• Oligosaccharides

• Disaccharides

• Monosaccharides And

• Polyols

Following a dietitian-guided elimination diet to identify trigger foods is one of the first steps I recommend. Once you’ve identified what is causing your symptoms, limiting foods that contain these compounds can help improve the quality of life for those living with IBS. So, the easiest way to adopt a low FODMAP diet that works for you is by having a dietitian work you through it. Due to my training in the low-FODMAP diet from Monash University, I have the skillset to customize a weight loss package geared toward helping those with IBS lose weight and live happier lifestyles. 

The Bottom Line on Your Question, “Can IBS Cause Weight Gain?”

Though scientists have found a link between obesity and IBS, it is unclear what the cause may be. However, it has shown that IBS itself is not a direct cause of weight gain. If you are experiencing weight gain with IBS, take a closer look at your eating and exercise habits to determine if there are other factors at play as a result of your IBS symptoms.

If you are worried about gaining weight while struggling with IBS or trying to lose weight, check out my services for support on how to do it healthily and without hassle.