IBD and Obesity: Risks, Links and Treatment Options

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IBD and obesity: the link, the risks and treatment options

By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv

IBD and obesity: a growing combination

IBD and obesity once seemed like two distant worlds. In the past, we pictured people with Crohn’s disease as thin and undernourished, but today the picture is different. According to a large study on Crohn’s disease and obesity, 15% to 40% of adults with Crohn’s disease also live with obesity. In this article, I will explain how the two conditions affect each other and what we can do about it today.

Inflammatory bowel disease (IBD) is an umbrella term for two main conditions. The first is Crohn’s disease, which can affect any part of the digestive tract, from the mouth to the anus. The second is ulcerative colitis, which usually affects the colon and rectum.

Does obesity raise the risk?

A pooled analysis of five cohort studies included 601,009 participants. The researchers found that obesity, meaning a BMI of 30 or more, was linked to a 34% higher risk of developing Crohn’s disease. In addition, every 5-unit increase in BMI raised the risk of Crohn’s disease by 16%. By contrast, the researchers found no link between obesity and ulcerative colitis.

What lies behind this link? Fat tissue, especially belly fat, is active tissue that releases inflammatory substances. I wrote about this mechanism in my article on obesity and inflammation, and I have also written about the role of gut bacteria in obesity and inflammation.

IBD and obesity: why the combination complicates things

First, obesity can reduce how well some medications work. A review of various inflammatory diseases, including Crohn’s disease, found that people with obesity responded less well to anti-TNF biologic drugs. These drugs block a key inflammatory substance in the body.

Second, a high body weight does not guarantee good nutrition. A review in The Lancet Gastroenterology & Hepatology describes how malnutrition in people with IBD can also show up as overweight, obesity or sarcopenic obesity. Sarcopenic obesity is a condition in which excess fat comes together with low muscle mass. That is why it is important to check muscle, vitamins and minerals, not just weight.

IBD and obesity: what about GLP-1 drugs?

GLP-1 drugs such as semaglutide and tirzepatide, which also acts on GIP, have transformed obesity treatment. However, people with IBD did not take part in the large trials that led to these drugs’ approval. A systematic review gathered 14 studies in people with IBD, and 13 of them were retrospective, meaning they relied on existing data. Most showed weight loss, and treatment was not linked to a worsening of the bowel disease.

Moreover, several large databases showed less steroid use, fewer hospital admissions and fewer surgeries among patients taking these drugs. On the other hand, a study that emulated a controlled trial in patients with stable disease found no change in the risk of flare-ups: 7.9% in both groups. In other words, as of today these drugs appear safe for people with IBD, but they are not a treatment for the bowel disease itself.

Common side effects, such as nausea, diarrhea or abdominal pain, can look like a flare-up. That is why it is important for the gastroenterologist and the obesity doctor to work together. You can find an overview of all the available drugs on my page about anti-obesity medications. I have also written about the new pill, orforglipron (Foundayo), and it is worth knowing that these drugs affect chronic inflammation.

Bariatric surgery in people with IBD

As a bariatric surgeon, I am asked about this quite often. A meta-analysis of 10 studies found that the rate of early complications after surgery was 15.9%, and the rate of late complications was 16.9%. In the year after surgery, patients lost an average of 66.1% of their excess weight. Nearly half of them reduced their medications for bowel disease.

With gastric bypass, the complication rate was 45.6%, compared with 21.6% for the sleeve, but the difference was not statistically significant. A review by the surgical society SAGES also found good results with the sleeve. So in most cases, the sleeve is the preferred operation for people with IBD. This is especially true in Crohn’s disease, where it is better not to change the structure of the small intestine.

Lifestyle, nutrition and exercise

A Harvard University study followed people with IBD for years. Among those who kept three to five healthy habits, the risk of death from any cause was about 71% lower. The habits included not smoking, a normal BMI, physical activity, a Mediterranean diet and drinking little alcohol.

Around the world, centers are emerging that combine medical treatment, nutrition and physical therapy for digestive problems and weight, such as the Digestive Centre in Singapore. In addition, there is interest in supplements such as berberine for fatty liver, but they are no substitute for treating the disease. It is also important to check out any pain in the upper abdomen, because sometimes the cause is something else entirely, such as Helicobacter pylori.

IBD and obesity: a shared treatment approach

The best care is team care. The gastroenterologist keeps the inflammation in check, and the obesity specialist builds a weight-loss plan. At the same time, the dietitian tailors nutrition to the stage of the disease. This way, we can choose the right time for medication or surgery and protect muscle mass. This is also the holistic approach that guides my work, connecting body, mind and research.

The bottom line

Obesity is common today among people with inflammatory bowel disease, and it is linked to a higher risk of Crohn’s disease. It may also weaken the response to some medications. Current data show that GLP-1 drugs are safe for most people with IBD and that sleeve gastrectomy is a good option for some of them. Ultimately, the decision is made together with your gastroenterologist and an obesity specialist. If you would like to find out what suits you, you can book a personal consultation.

This article provides general information and is not a substitute for personal medical advice.

Questions and answers

Does obesity cause Crohn’s disease?

Obesity is linked to a 34% higher risk of Crohn’s disease, but this is a statistical association, not proof of cause. By contrast, no link was found with ulcerative colitis.

Can people with IBD take weight-loss injections?

According to existing studies, yes, with a personalized approach and follow-up. However, most of the studies are retrospective, so it is important to coordinate with your gastroenterologist.

Which surgery is right for people with IBD and obesity?

In most cases, sleeve gastrectomy. Reviews found fewer complications with it than with gastric bypass.

Does weight loss improve bowel disease?

After bariatric surgery, nearly half of patients reduced their medications for bowel disease. Even so, we need controlled studies to know this for certain.