Does drinking extra water actually increase milk supply? A pediatrician told me this, but I’m not finding good research on it. How vital is it to drink more fluids when breastfeeding? What about calorie intake as well? Should I be consuming more calories?—Tired New Mom
You aren’t finding good research because there isn’t much! The 2014 Cochrane Review on the question of whether extra fluids increase breast milk production relies on a single “quasi-randomized” study from the 1950s. The study evaluated breast milk production by weighing infants before and after eating, which is imprecise. They didn’t find any impact of extra fluids on milk production, but it’s hard to make much of that.
On a non-research note, many women find that breastfeeding makes them incredibly thirsty. And, as in general, if you’re feeling thirsty, you are not well-hydrated. So you should drink water because hydration is great! But not for milk supply.
You do need more calories — about 400 to 500 more a day — while breastfeeding. This is a general guideline given by many organizations, but it has some support in (small sample, old) data, including this paper from the 1970s, which suggested that inadequate calorie consumption lowers milk supply and decreases breastfeeding success.
So: eating more, yes. Drinking fluids when you are not thirsty, no.