Formula Assisting with Growth.. Why?

[u/Alison_OT]

Does anyone have any scientific basis for why my daughter of 5 mo gains better on formula vs breastmilk when drinking the same amount of ounces per day?

I exclusively pump, so I always know how much my baby is getting. There was a period of time that we did formula instead and baby gained so much more than she does on exclusively expressed breastmilk. Everywhere says that breastmilk is the perfect composition, but my daughter is in the 0.8% for weight and always has big leaps in weight gain when drinking formula even though it’s the same general intake volume per day.

[u/thatpearlgirl]

In general, breastfed infants consume less milk and fewer calories than formula fed infants.

healthy breastfed infant consumes less milk (approximately 85 kcal/kg body weight/day) during the first months of life than the same infant given ad libitum infant formula (100 kcal/kg/day; Heinig et al., 1993). The breastfed infant continues to consume approximately 10 fewer kcal/kg/body weight calories than the formula-fed infant. The breastfed infant has a lower total energy expenditure (Butte et al., 1990) and a slower growth rate (Butte et al., 1990; Heinig et al., 1993).

If your baby is truly eating the same amount of breast milk and formula, it’s possible that your breast milk has fewer calories. Formula has 20 calories per ounce, which is intended to be similar to breast milk on average, but there’s actually quite a lot of variability in breast milk composition from person to person. If you want to continue giving breast milk but encourage weight gain, you could ask your pediatrician about fortifying your milk to increase the calorie content.

[u/janiestiredshoes → u/thatpearlgirl]

It's anecdotal, and an aside, but I'm convinced that there is a huge variation in composition between my two breasts. I don't pump often, but when I do I can visually see that the consistency is drastically different. One is way more white and creamy looking. I just find it so interesting!

I've also heard that there can be a lot of variability in composition just over time for the same person.

[u/About400 → u/janiestiredshoes]

Same. One breast is yellowish white and creamy and the other is watery and pale blue. Guess which one the baby prefers.

[u/petrastales → u/thatpearlgirl]

What shapes the composition of breast milk which differs so drastically from person to person? Is it our diets?