Complementary Feeding, Infant Growth, and Obesity Risk: Timing, Composition, and Mode of Feeding

The complementary feeding period is a short transitional period from breastfeeding and formula feeding to family foods. Timing, quantity, and quality are implied to impact growth and obesity risk. We summarized the literature and analyzed data of monthly 3-day food diaries of >1,000 children from 5 European countries in the first 2 years of life, which were collected as part of the prospective European Childhood Obesity Project (CHOP Study). Formula-fed children started complementary food approximately 2 weeks earlier than breastfed children, and almost 40% of them at or before 4 months of age. While introduction of solids between 4 and 6 months or after 6 months does not seem to impact growth and later obesity risk, solids before 4 months of age increased the risk. There are indications that this is especially problematic for formula-fed children. During the complementary feeding period, fat intake decreases, and protein and carbohydrate intakes increase. Protein intake often exceeds European recommendations from 9 months onwards. However, the role of macronutrients during complementary feeding in growth and metabolism needs further clarification. Findings on the role of responsive feeding or baby-led feeding during complementary feeding in growth are not conclusive. In summary, while introduction of complementary foods before 4 months of age should be avoided, the impact of the quality of complementary food on short-term growth and later obesity risk has to be elucidated further.