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Can IBS Cause Weight Gain? Yes and No. Here’s Why.

Feature, Food Relationship, Gut Health & IBS | October 3, 2022

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Our gut health dietitians at Ignite Nutrition often get asked about the connection between irritable bowel syndrome and weight – in particular, whether IBS can lead to weight gain. The short answer is yes, IBS and weight gain can be interconnected for some people. However, this topic is much more complex than that! Let’s discuss the connection between weight (both weight gain and weight loss) and IBS. 

A Note on Weight Neutral Nutrition Counseling

At Ignite Nutrition, we take a weight neutral approach. This means that we focus on ways to improve and optimize health without focusing on the number on the scale. We understand the stigma that exists around dieting and weight bias, as well as the fact that some individuals find comfort and safety associated with pursuing weight loss. 

Yes, fluctuations in our weight can tell us important things about our health. But, we want to ensure you are the best version of yourself, independent of your weight. Through managing our health and adopting positive behaviors, we aim to build a good relationship with our bodies, diets, and minds.

Let’s break down how IBS can alter weight and what that actually means for people living with IBS.

Man in green shirt and jeans sitting on a beige couch. He is holding his stomach with his left hand and holding his head with the other hand in deep thought. A text box reads "Can IBS Cause Weight Gain? Yes and No. Here's Why."

What influences our weight?

Beyond what we eat, what contributes to the weight we carry? There are multiple factors that contribute to how much we weigh. Some factors we can influence through our lifestyle, and some we can’t. Before we understand how IBS plays a part in our weight, we need to understand what actually dictates the size of our bodies.

Our age, sex, and genetic makeup have a significant influence on our weight independent of lifestyle. Together, they give us our own personalized code that accounts for how each individual carries weight. The other part is influenced by lifestyle factors such as sleep, stress, exercise and, of course, what we eat! All factors are playing a role but some (like genetics!) play a bigger part in how much we weigh.¹

Medications can also influence our weight. Some medications suppress appetite, while others make us feel more hungry – which can then relate to weight changes. However, the medications we are prescribed are meant to help us. If you are curious about how your medications may be influencing your weight, please talk to your doctor. Do not discontinue any medication without physician supervision. 

Additionally, managing stress, staying active, and getting enough sleep have significant benefits to overall health and our IBS management!² ³ ⁴ It is important to understand that we are made up of more than what we eat. Learning about how to manage IBS and build healthy and sustainable habits is a fantastic way to start.

Do IBS symptoms influence our weight?

Some of the symptoms that individuals can experience with IBS may impact body weight. Other symptoms may only appear to impact body weight, or have no effect at all! 

Diarrhea and Constipation

Persistent diarrhea in cases of IBS-D is associated with weight loss, whereas significant bouts of constipation may be associated with a temporary increase on the scale due to a build up of stool.

In cases of IBS-D, persistent diarrhea can contribute to unintentional weight loss due to poor nutrient absorption. To compensate for this, people experiencing IBS-D flare up produce more ghrelin, a hormone that stimulates hunger and therefore weight gain in some cases.⁵ This is one of the many ways that our bodies are looking out for us.

Bloating and Distention

Abdominal distention associated with gas and bloating may appear as if there has been weight gain. However this is usually related to water retention and increased air in the digestive tract– neither of which are true weight gain!⁶

Heartburn and GERD

For people who experience heartburn or GERD related to their IBS, weight gain is also common. This is not due to the heartburn itself, rather the way we manage the symptoms. It is common for people experiencing reflux to eat more often to prevent acid flare ups from large, widely spaced meals. This also can mean a greater food intake overall which can lead to weight gain. Smaller, more frequent meals can improve symptoms and choosing nutritious foods can help fuel our bodies adequately.⁷

Eating Patterns During IBS Flare-ups

Our relationship with food can be complicated by symptom flare ups. It is common for people with IBS to fast for long periods of time or avoid eating in an attempt to relieve their symptoms which can lead to weight loss.⁸ If you find yourself struggling with your relationship with food and managing symptoms, consulting with a Registered Dietitian or Psychologist may be beneficial to support a healthy mind-gut connection.

How IBS Influences Diet and Food Choices

Of course gut issues can influence what we eat! A healthy, balanced diet is completely achievable for people with IBS. However, it is common for people with IBS to limit their dietary variety in hopes of preventing flare ups. 

This lack of variety is typically driven by a focus on “safe foods”, or particular foods that people with IBS know won’t trigger their symptoms. Limiting the types of foods we eat can lead to nutritional imbalances and overeating, which in turn can lead to weight gain. 

These “safe foods” are often lower in fiber and higher in simple carbohydrates and/or fat. They can also be more calorically dense (ie. have more energy) and less filling, such as white rice, sourdough or gluten-free bread. All of these factors contribute to an increased intake which can contribute to weight gain. 

Think of it this way– even if our bodies are getting enough energy, they may be missing other nutrients, like protein, vitamins, and minerals. If this is the case, our bodies will ask for more food in hopes of filling those gaps – ie. we’ll get hungry! By limiting variety, we can end up overeating energy dense foods and still being deficient in certain nutrients.

Isn’t the human body fascinating?

Fiber is especially important for IBS management. It helps us feel full and keeps things in the bowels moving the way we want it to. Foods like oats, banana, strawberries, quinoa, canned lentils and chickpeas, kiwi, chia seeds, walnuts, hemp hearts and pumpkin seeds are all IBS safe ways to increase fiber intake and variety without compromising your gut. These nutritious foods can help prevent nutrient deficiencies and prevent overeating by nourishing our bodies and keeping us satiated.

IBS and Exercise

Exercise plays an important role in IBS management and additionally can influence our weight. In general, it’s common for people with IBS to exercise less when they are experiencing a flare up in symptoms, which may impact weight if they were previously active. 

Oftentimes, IBS symptoms can influence people to change types of activity or avoid it altogether. Running, jumping, and high-intensity exercise can trigger IBS symptoms like urgency and diarrhea for some.⁹ These types of exercise have high energy demands as well, so some people experience a change in weight if they switch to lower intensity exercise like yoga, walking, or swimming 

Staying active is an important part of managing IBS and living a healthy life, so at Ignite Nutrition, we encourage finding a way you like to move. Exercise is about much more than your weight. Whether that’s dancing, taking the dog for a walk, swimming, or biking, whatever you enjoy and feels comfortable – get moving!

So is IBS and weight gain connected? 

Yes, they can be but that doesn’t mean weight gain is inevitable. Although IBS-D is most often associated with unintentional weight loss, weight gain is also possible due to many different factors in IBS management. And of course, some people don’t notice weight changes at all. 

Our weight is primarily influenced by biological factors such as genetics, age, and sex, although exercise, sleep, stress management and our diet also play a role. For individuals with IBS, symptoms themselves, as well as how we change our diets to manage IBS, can lead to either unintentional weight loss or weight gain. Each body’s response to IBS is unique depending on their genetic make-up, symptoms, severity, and IBS management style. Changes in lifestyle such as lowering exercise intensity or significantly limiting variety in the diet can also be associated with changes in weight. 

Sometimes, IBS can make it difficult to know the difference between weight gain and retention of gas and/or stool. Although abdominal distention, gas, and bloating may appear as if weight has changed, this is typically due to air and water retention in the gut and not a reflection of actual weight fluctuations. Finding physical activity that works for you and incorporating a variety of nutritious foods into your routine can help optimize your gut and your overall health.

I Have IBS and Have Gained Weight: What Now?

Start with reflection – Am I being considerate of what my body is going through? For example, for an individual who was experiencing persistent diarrhea, gaining weight in the weeks after symptoms resolve may be a good thing! If our previously unhappy gut wasn’t absorbing nutrients well during a flare up, it can be a relief to know that our body is now benefiting from the foods we eat.

Back to Basics – Working on our health is a lifelong process! Start by going back to the basics and setting small, achievable goals. This is the best way to re-integrate healthy eating habits that also support your IBS.

Find what moves you  Discover what types of activity you actually enjoy and dive in! Many of us have never thought of activity like this. It’s not all about burning energy; it’s also about joyful movement that doesn’t feel like a punishment!

Work with a Registered Dietitian – Working with a professional can add that personalized edge to ensure your mind, body, and diet are all cared for. Our gut health RDs at Ignite Nutrition are highly specialized. We offer both in person and virtual support across Canada. 

Man in green shirt and jeans sitting on a beige couch. He is holding his stomach with his left hand and holding his head with the other hand in deep thought. A text box reads "Can IBS Cause Weight Gain? Yes and No. Here's Why."
Can IBS make you gain weight?

Yes, in some cases IBS can lead to weight gain. This can be related to diet changes to reduce symptoms, changes in eating pattern and timing of meals, increase in stress, or reduction in exercise due to feeling unwell. Learn more.

Does bloating cause weight gain?

Bloating and weight gain are not the same thing. Although your abdomen may appear distended when feeling bloated, this is usually related to water retention and increased air in the digestive tract– neither of which are true weight gain. However, IBS may cause weight changes for other reasons.

Does constipation cause weight gain?

Significant bouts of constipation may be associated with a temporary increase in body weight due to a build up of stool. You may also notice increased bloating and distention, which can appear like you’ve gained weight. Learn more about IBS symptoms that influence weight.

Andrea Clarke
About the Author

Andrea Clarke

Andrea Clarke is a registered dietitian, certified intuitive eating counsellor, and registered yoga teacher. Her mindfulness skills help her to support patients with ending their chronic dieting, finding the joy in eating again, and improving their relationships with their bodies. She is also very skilled in digestive disorders. Andrea also offers a specialized program called 'Nourished Freedom Food Relationship Intensive' for those looking to do deep work on their food relationship.

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