Does breastfeeding affect the risk of childhood obesity?
EVIDENCE-BASED ANSWER:
Yes. Ever having breastfed during the first year of life is associated with a 15% lower risk of overweight or obesity over the next 2 to 14 years compared with never having breastfed. Breastfeeding exclusively for 6 months is associated with a 30% to 50% reduction in risk (strength of recommendation [SOR]: B, meta-analysis of cohort studies and subsequent cohort studies). However, interventions that increase breastfeeding rates during the first 3 to 6 months of life don’t appear to alter body mass index (BMI) at 11 to 12 years of age (SOR: B, randomized clinical trial [RCT]).
Introducing complementary (solid) foods before 3 months is associated with a 30% greater risk of childhood obesity than later introduction; starting solid foods after 4 months isn’t linked to increased obesity. High caloric density of complementary feedings may be associated with greater childhood obesity (SOR: C, systematic reviews of heterogeneous cohort studies).
Scheduled feeding doubles the risk of rapid infant weight gain compared with on-demand feeding, although it’s unclear whether a direct relationship exists between rapid infant weight gain and childhood obesity (SOR: B, cohort study).
Eight of the 21 studies that used BMI as an outcome found that early introduction of complementary foods was associated with a higher childhood BMI. In the largest study (a cohort of 17,561 infants), introducing complementary foods before 3 months was associated with higher risk of obesity at age 5 years than introducing them thereafter (OR=1.3; 95% CI, 1.1-1.6).6 Introduction of solids after 4 months was not associated with childhood obesity.
A systematic review of 10 primarily cross-sectional and cohort studies with more than 3000 infants evaluated associations between the types of complementary foods given and the development of childhood obesity.7 Six of the 10 studies were from Europe and none were from the United States. Follow-up ages ranged from 4 to 11 years.
Outcomes were heterogeneous, and no meta-analysis could be performed. The authors cited 3 studies (total 1174 infants) that found various positive associations between total caloric intake during complementary feeding and childhood obesity. No consistent evidence pointed to increased risk from specific foods or food groups.
Scheduled feeding is linked to rapid infant weight gain
A cohort study evaluated the baseline data of an Australian RCT (on an intervention to promote proper nutrition) in 612 infants, mean age 4.3 months.8 Researchers looked at the relationship between feeding on demand vs scheduled feeding (assessed by parental report) and weight gain in infancy. “Rapid weight gain” was defined as >0.67 change in weight-for-age Z-score between birth and enrollment.
Scheduled feeding was associated with rapid weight gain at a higher rate than feeding on demand (OR=2.3; 95% CI, 1.1-4.6). This study didn’t use childhood obesity as an outcome.
