What Is Creeping Fat?

A type of fat found in people with IBD may be related to inflammation

Creeping fat is a phenomenon found in patients with Crohn's disease and ulcerative colitis (two types of inflammatory bowel disease, or IBD) that is still not well understood by the medical community. In fact, it has not yet been studied extensively, even though its existence in patients with Crohn's disease has been known for several decades. Crohn's disease is named for Burrill Crohn because he was the one who first described the disease that was formerly known as regional ileitis. Dr. Crohn described the changes in the adipose tissue (connective tissue, or fat) in patients that had Crohn's disease.

What Is Creeping Fat?

Everyone has fat in their body, and at least a certain amount of fat in the abdomen. Between 15% and 30% body fat is considered normal, even healthy. Rather than just being a part of the body that is passive, adipose tissue is now recognized as an actual organ. It even has a function and secretes different chemicals. One type is cytokines, which have been associated with IBD because they're found in greater numbers in people who have these diseases as opposed to healthy people. There have been cases where it was found that as much as 50% of the intestine was encased in creeping fat. Not surprisingly, having more of this type of fat is associated with having a more severe case of Crohn's disease.

Previously, creeping fat was thought to be diagnostic of Crohn's disease—that is to say, when it was found, the patient was presumed to have Crohn's. Creeping fat can be seen on a computed tomography scan. However, it has been described that patients with ulcerative colitis may also have a form of creeping fat. Most of the knowledge on creeping fat until now focused on Crohn's disease, so relatively little is known about it in ulcerative colitis or indeterminate colitis.

The "Fat" Part of Creeping Fat

Creeping fat is not the same as the type of fat we would associate with overweight or obesity. Having this type of fat doesn't mean a person is overweight, nor does it contribute to being overweight or obese. Most patients with Crohn's disease are either at what is considered a low body-mass index, or a healthy body-mass index. It's not unheard of for a person with IBD to be overweight or obese, but it's not common either. One study found that 21% of people with Crohn's have creeping fat, which can lead to bowel damage and surgery.

What to Do About Creeping Fat

One question people with IBD may ask is how to prevent creeping fat or what can be done about it if it is present. Even though we've known about it since the 1930s, there is a paucity of research on creeping fat. The exact mechanism of how it affects the course of IBD is not understood, though there are several theories. Some theories are focused especially on the chemicals secreted by the fat and how they affect inflammation and the inflammatory process. One study showed that the fat has a role in promoting inflammation and that targeting creeping fat may be a future focus of treatment.

It's also not known exactly why it occurs. Does it occur before the IBD, and have a role in its cause, or is it a result of the IBD? These are questions that research must answer, as scientists begin to uncover this aspect of IBD that so far has been largely ignored.

5 Sources
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  2. American Council on Exercise. Percent body fat calculator: skinfold method.

  3. Zielińska A, Siwiński P, Sobolewska-włodarczyk A, Wiśniewska-jarosińska M, Fichna J, Włodarczyk M. The role of adipose tissue in the pathogenesis of Crohn's disease. Pharmacol Rep. 2019;71(1):105-111. doi:10.1016/j.pharep.2018.09.011

  4. Golder WA. The "creeping fat sign"-really diagnostic for Crohn's disease?. Int J Colorectal Dis. 2009;24(1):1-4. doi:10.1007/s00384-008-0585-y

  5. Althoff P, Schmiegel W, Lang G, Nicolas V, Brechmann T. Creeping fat assessed by small bowel MRI is linked to bowel damage and abdominal surgery in Crohn's disease. Dig Dis Sci. 2019;64(1):204-212. doi:10.1007/s10620-018-5303-1

Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.