Abstract P246: Determinants of Remission of Overweight Status in Youth
Authors: McGavock Jonathan , MacIntosh Andrea , Sadman Rashick , Torrance Brian , Ball Geoff , Plotnikoff Ron , Majumdar Sumit , Boule Norman , Wozny Paul , Lewanczuk Richard 
Published: July 2021

Introduction and hypothesis:
Spontaneous remission to normal weight status occurs in ~10-20% of overweight youth. The factors that predict remission, particularly modifiable factors such as diet and physical activity (PA) are poorly understood. We hypothesized that the time spent in moderate to vigorous physical activity (MVPA), high fitness and better diet quality would be associated with an increased likelihood of remission to normal weight status among overweight youth.

Design and Methods:
This was a three year prospective cohort study of 114 youth aged 9-15 years who were overweight or obese (International Obesity task Force (IOTF) cut-points) at baseline. We performed a series of regression analyses to test for predictors of remission to normal weight status at the 3-year follow up visit. The primary exposure variables were accelerometer (Actical) determined physical activity (PA) intensity, cardiorespiratory fitness assessed with a 20m shuttle run and diet quality determined from a web-based 24-hr recall tool that estimated diet quality based on meeting recommendations for daily intake of food groups. The primary outcome measure was remission to normal weight status defined as a BMI within the “healthy weight” range for age and sex in year 3 of the cohort study according to IOTF cut-points. We also tested for differences in BMI Z-score and systolic blood pressure (SBP) between youth that experienced remission and those that didn’t. We adjusted for the potential confounding effects of sedentary time, age and sex.

Results:
Among the 114 overweight youth studied (12 ± 2 years; BMI Z score = 1.55 ± 0.35), 18 (16%) returned to normal weight status at year 3. Remission did not occur in any youth considered obese (BMI [[Unable to Display Character: &#707;]] 95th percentile) at baseline. Neither MVPA nor dietary quality was associated remission. However, remission was associated with a lower BMI Z score at baseline (1.31 ± 0.15 vs. 1.60 ± 0.35, p < 0.05) and a higher cardiorespiratory fitness (shuttle run score = 6.4 ± 2.3 vs. 4.9 ± 1.9, p < 0.05). The odds of remission were 4-fold higher (OR: 4.2 95% CI=1.04-16.7) among youth in the two upper quintiles of cardiorespiratory fitness compared to those in the lowest quintile. Despite a significant decline in BMI Z score over 3 years (-0.67 ± 0.53 vs. -0.019 ± 0.23, p < 0.05) in youth that experienced remission, no differences in SBP were observed compared to youth that remained overweight.

Conclusions:
Remission to normal weight status was observed in 16% of youth who were overweight at their initial assessment. Obesity and low cardiorespiratory fitness reduced the likelihood of spontaneous remission to normal weight status in overweight youth. The identification of BMI and fitness thresholds at which spontaneous remission is unlikely to occur will tailor interventions to youth with the greatest need to improve lifestyle behaviours, weight status, and overall well-being.