A new study published in The Journal of Nutrition concluded that added sugars in infant formulas predict rapid weight gain in infants and toddlers.

Although studies have reported a positive relationship between infant formulas and excessive weight gain in infants and toddlers, a complete understanding of this phenomenon has been challenging. Trials comparing intakes of low-protein compared with high-protein formulas have failed to identify conclusive connections to body weight or adiposity, suggesting that other factors are at play. It is well established that high intake of added sugars is positively correlated with overweight and obesity in children and adults. However, the relation between added sugars specifically from infant formulas and rapid weight gain is not clear. To determine the contribution of added sugars in formulas compared with those in beverages and foods (i.e. table foods) on rapid weight gain, Kai Ling Kong (Children’s Mercy Kansas City, University of Missouri-Kansas and University of Kansas Medical School) and colleagues analyzed data from three 24-hour dietary recalls for infants (9 – 12 months of age) and toddlers (13 – 15 months of age).

Sources of sugars included milk-based (breast milk and/or formulas) or table foods. Based on the World Health Organization’s infant growth charts, the number of major percentile thresholds crossed from birth to point-of-contact assessment was determined as an indicator of rapid weight gain. Participants crossing a higher threshold percentile were considered to have an upward crossing; participants crossing a lower threshold or staying in the same band between major percentiles were considered to not have an upward crossing.

Infants consumed more added sugars daily than toddlers. Added sugars from all sources were significantly related to rapid weight gain, and these sources differed by age group. Specifically, the majority of added sugars consumed by infants were from formulas, while the majority of added sugars consumed by toddlers were from table foods. Study findings reveal that added sugars in formulas predict rapid weight gain as early as 9 months, and daily amounts of added sugars consumed by primarily formula-fed individuals are almost double those of primarily breast-fed individuals. Furthermore, this study demonstrated that the contribution from added sugars in predicting rapid weight gain was stronger than that of protein.

A corresponding editorial by Gemma Bridge (Queen Mary University of London) states that the low rate of exclusive breastfeeding and high rate of alternative feeding methods, including infant formulas, could have profound impacts on child health. Efforts to market, sale, and consume toddler milk are both unnecessary and possibly harmful to child health. 


Kong KL, Burgess B, Morris KS, Re T, Hull HR, Sullivan DK, Paluch RA. Association Between Added Sugars from Infant Formulas and Rapid Weight Gain the US Infants and Toddlers. The Journal of Nutrition, Volume 151, Issue 6, June 2021, Pages 1572–1580, https://doi.org/10.1093/jn/nxab044.

Bridge G.  Consider the Whole Picture When Discussing Infant Formula and Breast Milk. The Journal of Nutrition, Volume 151, Issue 6, June 2021, Pages 1375–1377, https://doi.org/10.1093/jn/nxab132.

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