Do you have Ulcertaive Colitis? BMI may not be right index for you.

Before we dive into research, let’s do some simple math. This will help you understand the logical application of this article. Let’s imagine an average ulcerative colitis patient named Roberta. Her weight is 60kg, which is within her correct BMI zone. However, she experienced a major flare-up, causing her to lose 10kg. Let’s assume she was lucky, and the ratio of this weight loss was 7:3 fat to muscles, meaning she lost 7kg of fat and 3kg of muscles. After treatment, she gained back those 10kg. However, because she wasn’t exercising, all that 10kg is fat now. So, Roberta still weighs 60kg, and her BMI is correct, but she now has an extra 3kg of fat. As fat is less dense compared to lean muscle, that 3kg is now visible around her waist. However, from the BMI point of view, she is still in the healthy weight range. Then, let’s say the situation repeats after a few years, and she loses 7kg of fat and 3kg of muscles again. But, because of the lack of strength training, all her gains are back in fat tissue. Now, she has an extra 6kg that is probably hanging around her waist. However, her BMI is still in the healthy range.
Sounds familiar?

Mentioned earlier reaserch is a 2021 study titled “Body Composition Changes and Related Factors in Patients with Ulcerative Colitis: A Retrospective Single-Center Study in China” by Wang, Ding, Tian, and Jing. The study included a total of 80 patients with active Ulcerative Colitis (UC) and 80 healthy controls. The study found that the UC group had a significantly higher prevalence of low Skeletal Muscle Index (SMI) compared to the control group, indicating greater muscle mass loss. Interestingly, the study also revealed that 62.5% of UC patients with a normal body mass index (BMI) also had low Skeletal Muscle Index (SMI), highlighting the limitations of BMI in assessing body composition in Ulcerative Colitis (UC).

Further, the study found a significant association between disease severity and the prevalence of malnutrition. Patients with severe UC had a higher prevalence of malnutrition as compared to those with mild or moderate UC. Similarly, the study observed a significant association between disease extent and low Skeletal Muscle Index (SMI). Patients with a more extensive UC involvement had a higher prevalence of low SMI compared to those with less extensive disease.

Therefore, this study suggests that patients with UC, particularly those with severe disease, experience significant muscle mass loss and malnutrition. The extent and severity of UC were found to be associated with the degree of muscle mass loss.

To summaries: People who suffer from inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn’s disease (CD), often experience changes in their body composition. These changes may include a reduction in muscle mass, protein depletion, and an increase in abdominal fat. These changes are caused by a combination of factors, such as poor absorption of nutrients, inadequate food intake, loss of nutrients, and an increased demand for nutrients. These alterations in body composition can lead to malnutrition, low muscle mass, sarcopenia, and an unfavorable prognosis.

A low skeletal muscle index (SMI) can have a significant impact on your overall health and well-being. Here are some key areas that can be affected:
Fatigue: Reduced muscle mass results in decreased strength and endurance, making even simple tasks feel tiring. Studies have shown that low SMI is linked to increased fatigue, which can have a negative impact on daily functioning and quality of life. (
Joint health: Muscles play an important role in supporting and stabilizing our joints. With low SMI, joints become more vulnerable to injury and wear-and-tear, which can increase the risk of falls, osteoarthritis, and overall joint pain. This can further limit mobility and independence. (
Overall well-being: Low SMI can have a domino effect, negatively impacting various aspects of your well-being. It can hinder physical activity levels, which can affect mental health, sleep quality, and immunity. Additionally, low muscle mass can decrease metabolic rate, making weight management more challenging. (




Thank you for taking the time to visit my blog. My name is Vic and I have a strong passion for fitness and health. I have been working in this field for many years, assisting people in achieving their goals, including weight loss or muscle gain, and supporting patients with medical conditions in their rehabilitation journeys.