Researchers at the Beth Israel Deaconess Medical Center, including Celiac Disease Foundation Medical Advisory Board Member Dan Leffler, conducted a study to determine the effects of the gluten-free diet (GFD) on weight changes in celiac patients after diagnosis. The authors note that while weight gain would be welcome and expected in initially underweight patients, similar weight gain in patients with initially normal weight, or who are overweight or obese at diagnosis, would be very unwelcome.

Though celiac patients were found to have a lower BMI (body weight in kg/height in m2) at diagnosis than healthy controls, celiac patient BMI increased on the gluten-free diet, especially in those adhering strictly to the diet. Overall, the results showed that most patient weight stayed in the same BMI category, but that weight gain is common and increases over time. This indicates that weight management should be an important part of nutritional counseling for patients with celiac disease.

The study included 679 patients in the Northeast United States with biopsy-confirmed celiac disease and records of BMI and GFD adherence from at least two separate visits: at diagnosis and at follow-up. The celiac group was compared with healthy adults in the same region, using data from the National Health Interview Survey (NHIS).

BMI were classified per the World Health Organization criteria as underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), or obese (≥30).

In patients who were underweight at diagnosis, 30.4% remained underweight at follow-up, 65.2% attained a normal weight, and 4.4% became overweight or obese.

In patients who were a normal weight at diagnosis, 80% remained a normal weight at follow-up, but 17% became overweight or obese.

In patients who were overweight at diagnosis, 64% remained overweight at follow-up, while 18.7% attained a normal weight and 17.3% became obese.

Of patients that were obese at diagnosis, 87.2% remained obese and only 1.3% became normal weight.

The researchers found that the mean BMI of the celiac patients increased after initiating a gluten-free diet (from 24.0 to 24.6). This increase was seen predominantly in the gluten-free diet adherent group (501 patients) rather than the non-adherent group (178 patients). Regardless of diet adherence, the researchers found that increases in BMI were directly related to duration of follow-up, suggesting ongoing weight accumulation.

In all adherence groups, the majority of individuals were in a normal BMI range. However, patients who were overweight or obese at diagnosis were more likely to be poorly adherent to the GFD over time. This might be due to behavioral or food-related differences that contribute to excess weight gain and poor adherence.

When comparing overall changes in BMI based on diet adherence, there was no significant difference between patients with good adherence vs. poor adherence to the gluten-free diet.

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