27/09/2025
The incidence of inflammatory bowel disease (IBD) is rising among people living with obesity, prompting researchers to explore whether excess weight influences the natural course of the disease.
To investigate this, a population-based study analyzed health data from individuals newly diagnosed with Crohn’s disease (CD). The findings were published in 2024 in the Journal of Clinical Gastroenterology.
“Current evidence suggests that obesity, particularly an increase in visceral fat, may negatively influence certain outcomes in IBD — including a higher likelihood of penetrating or fibrostenotic disease, reduced effectiveness of biologic therapies, and an increased risk of Crohn’s relapse after surgery. However, the exact mechanisms remain unclear,” explained Dr. Amandar M. Johnson, gastroenterologist and lead author of the study.
Study Objectives
Dr. Johnison and colleagues set out to measure the prevalence of obesity among people with newly diagnosed Crohn’s disease and to evaluate its potential impact on disease behavior and related outcomes — such as corticosteroid use, hospital admissions, bowel resections, and the development of fistulas or penetrating disease.
Methods
The team conducted a retrospective analysis of patients with Crohn’s disease who had a recorded body mass index (BMI) within six months of diagnosis. They calculated the proportion of patients classified as obese at diagnosis and tracked how this prevalence changed across four decades. Using survival analysis, they examined CD-related complications including hospitalizations, corticosteroid use, and surgeries.
Results
Among 334 patients, 156 (46.7%) were classified as either overweight (27.8%) or obese (18.9%) at diagnosis.
Overweight and obese patients were, on average, diagnosed later in life (42.3 and 44.3 years) compared with those of normal weight (35.8 years) or underweight (31.6 years).
The proportion of obese patients at diagnosis more than doubled over time — from about 9% in the 1970s to over 20% in the 2000s.
Despite this increase, obesity at diagnosis was not associated with a greater long-term risk of corticosteroid use, hospitalizations, bowel resections, or the development of penetrating or fibrostenotic complications.
Conclusion
“Our study highlights that obesity at the time of Crohn’s diagnosis has become increasingly common, with rates more than doubling in recent decades,” noted Dr. Johnson. “It’s also important to recognize that we specifically assessed weight status at diagnosis, meaning factors such as weight gain from corticosteroid therapy or smoking cessation, which can occur later, were not captured.”
