Associations of Breastfeeding, Diet Quality and Physical Activity with BMI in Adolescents
Authors: Shields Emily , Shanahan Lilly , Wideman Laurie , Calkins Susan , Keane Susan , Lovelady Cheryl 
Published: November 2023

Breastfed infants have a reduced risk of becoming overweight or obese during childhood compared to formula fed infants. However, there is little evidence to assess whether this protective effect of breastfeeding persists into adolescence. As rates of obesity rise in adolescents, it is important to determine if breastfeeding in early infancy continues to have a protective effect on obesity, while also examining the health behaviors of diet and exercise to see if they are related to BMI. Therefore, the purpose of this study was to determine if there was a relationship between physical activity and BMI, diet and BMI and breastfeeding and BMI during adolescence. Participants were 16‐year olds: 97 female, 65 male; 65% White, 28% Black, 6% other race. Dietary intake was determined from three, 24 hr‐dietary recalls using the Nutrition Data System for Research. Data was used to calculate the Healthy Eating Index‐2010 (HEI) with possible scores ranging from 0 to 100. Physical activity was determined using the Godin Leisure‐Time Exercise Questionnaire, asking participants the number of times during the past week they completed strenuous (scored 9), moderate (scored 7), and mild exercise (scored 3) for more than 15 minutes. Godin Score was calculated by weighting and summing the number of times all 3 types of activity occurred. Mothers were asked if they had breastfed their child, and if so, for how long and if breastfeeding was supplemented with formula. Breastfeeding intensity was calculated from the number of months the child was breastfed and whether it was exclusive (score of 2 given for each month of exclusive) or mixed with formula (score of 1 given for each month of mixed feeding) for the first 6 months. Scores could range from 0 (no breastfeeding) to 12 (exclusive breastfeeding for 6 months). Average BMI was 24.7 ± 6.6 for females and 24.1 ± 5.9 for males. Seventeen% of males and 15% of females had BMI ≥ the 95th percentile. Mean HEI score for females was 50.1 ± 12.7 and for males it was 47.8 ± 10.9, p=0.21. Males reported significantly more activity than females (males, 62.5 ± 49.6; females, 44.6 ± 32.1, p= 0.02). Mean breastfeeding intensity score was 7.0 ± 5.2 for females and 8.0 ± 4.6 for males, p= 0.27. Breastfeeding (r = −0.28, p= 0.001) and HEI (r = −0.16, p= 0.04) were significantly related with BMI; but not Godin score. There were no significant relationships between breastfeeding and HEI; however, breastfeeding and Godin score were significantly related (r= 0.19, p=0.03). In a multivariate regression analysis examining gender, race, SES, HEI, Godin score, and breastfeeding, the only significant predictors of BMI were race and breastfeeding (R2=0.12, p<0.001). For every increase in breastfeeding intensity, BMI decreased by 0.27 units. White adolescents had lower BMI's than non‐white adolescents (β= −3.42). There were no interaction effects of HEI and physical activity and breastfeeding on BMI. These results suggest that breastfeeding in early infancy may reduce the risk of obesity in adolescence.Support or Funding InformationThis research was supported by funding from NIH (1R01HD078346)