Body Mass Index Variability During Weight Loss Treatment and Risk Factors for Cardiovascular Disease

To explore the effect of body mass index (BMI) variability on cardiometabolic risk in children with obesity.

Children between 8 and 18 years, entering a 12-month inpatient or 18-month outpatient obesity treatment were studied. BMI, body composition, blood pressure, high-sensitivity C-reactive protein, lipid profile, insulin sensitivity, and endothelial function were assessed at baseline and follow-up (every 3 months for outpatients; at 12 and 18 months for inpatients). BMI evolution was modeled via linear regression for each patient, with the slope indicating BMI evolution and root mean square error (RMSE) reflecting BMI variability. These were correlated with changes (Δ) in risk factors between baseline and the final visit.

Eighty-three patients were included (mean age 12.8 ± 2.4 years, mean BMI 32.8 ± 5.5 kg/m², 36 boys, 45 inpatient). By 18 months, BMI significantly decreased by 3.5 ± 3.6 kg/m², resulting in an average BMI slope of -0.19 ± 0.21 kg/m²/month and a median RMSE of 2.75 (0.97 - 4.58). The slope significantly related to changes in body composition, insulin sensitivity, high-sensitivity C-reactive protein, high-density lipoprotein-cholesterol, and endothelial function. The RMSE did not significantly correlate with changes in cardiometabolic factors or endothelial function after correcting for age, sex, and pretreatment BMI and slope, except for a correlation with Δlean% (r = -0.75) and Δhigh-density lipoprotein(r = -0.44), both P < .001.

Only overall BMI evolution was significantly related to the cardiometabolic risk factors and endothelial function, indicating that overall weight loss is the most important in children with obesity even if BMI fluctuates during the weight loss process.