What's In the Bottle?

Scientists have found that babies not breastfed have a 30% to 40% increased risk of childhood obesity.1 Milk intake and weight gain vary greatly among formula-fed and breastfed babies.  (For more, see my earlier post.) Formula-fed babies consume 49% more milk at 1 month, 57% more at 3 months, and 71% more at 5 months.2 This significant difference in milk intake is due in part to how milk flows from breast and bottle.  Recent studies have examined these feeding differences in more detail to help answer the question “How is obesity risk affected when the feeding bottle contains mother’s milk?”  

The study mentioned above provides a partial answer.  Caregivers’ behaviors during bottle-feeding—which are independent of the milk—influence babies’ intake.  For example, when bottles contain more than 6 oz. (177 mL), babies consume more milk.  Also, babies whose caregivers encourage them to finish the bottle are heavier than other babies. 

An important part of obesity prevention is the ability to self-regulate what we eat to match our energy needs.  Breastfeeding naturally teaches babies this self-regulation by giving them more control over feedings.  While breastfeeding, baby must actively draw milk from the breast.  He learns to take milk when hungry and stop when full.  This helps baby become attuned to his body’s hunger and satisfaction cues.  During bottle-feeding, baby’s role is more passive.  Fast, consistent flow and regular coaxing to take more milk, even when full, can lead to a habit of overfeeding and poor self-regulation. That's why if your baby will be bottle-fed often, rather than just laying baby back and tilting the bottle up, use the pacing techniques described HERE.

In one recent study of 1250 U.S. babies, researchers used bottle-emptying as a measure of poor infant self-regulation.3 (An earlier study verified this link.4) It didn’t matter whether expressed milk or formula was in the bottle.  The more often the babies were fed by bottle during their first 6 months, the more likely they were to empty the bottle during their second 6 months.  Only 27% of the babies who were exclusively breastfed during their first 6 months emptied the bottle during their second 6 months.  Of those fed at first by both breast and bottle, 54% later emptied the bottle.  Of those fed at first only by bottle, 68% later emptied it.

Mother’s milk plays a vital role in a healthy beginning.  But as these studies demonstrate, there is more to breastfeeding than the milk.  Even when mother’s milk is in the bottle, regular bottle-feeding can increase a baby’s risk of childhood obesity. One way we can offset this effect is to make bottle-feeding more like breastfeeding using pacing techniques, which hopefully will decrease the risk of overfeeding.


1 Dewey, K.G., Infant feeding and growth.  In G. Goldberg, A. Prentice, P.A. Filtreau, S., & Simondon, K. (Eds.)  Breastfeeding : Early influences on later health (pp. 57-66).  New York, NY: Springer.

2 Kramer, M. S., Guo, T., Platt, R. W., Vanilovich, I., Sevkovskaya, Z., Dzikovich, I., et al. Feeding effects on growth during infancy. Journal of Pediatrics 2004; 145(5): 600-605.

3 Li, R., Fein, S.B., & Grummer-Strawn, L.  Do infant fed from bottles lack self-regulation of milk intake compared with directly breastfed infants?  Pediatrics 2010; 125(6): e1386-e1393.

4 Li, R., Fein, S.B., & Grummer-Strawn, L.M.  Association of breastfeeding intensity and bottle-emptying behaviors at early infancy with infants’ risk for excess weight at late infancy.  Pediatrics 2008; 122 Suppl 2: S77-S84.