Breastfeeding and calories and weight, oh my!

Here’s another question that pops up frequently: “I want to lose weight, but I don’t want to lower my milk supply. What should I do?”

First, let’s get out our calculators!

There is an average of 22 calories in an ounce of breastmilk. The average intake for a breastfed baby between 1 and 6 months of age is 25 ounces per day. (The blog posts linked contain references for these figures.)

22 calories/ounce x 25 ounces = 550 calories

This is where the “breastfeeding burns 500 extra calories per day” comes from. Given that not everyone produces the same amount of milk, whether breastfeeding directly from the breast or pumping, not everyone will burn 550 calories a day. Some will use more, and some will use less. If you’re nursing twins, you’re converting roughly 1100 of the calories in your body into breastmilk. If you meet half of your baby’s needs with your own breastmilk, you’re converting 225 calories into breastmilk. When your baby gets older than (roughly) six months and starts consuming solid food, breastmilk intake will go down and you’ll be burning fewer calories. Breastfeeding a toddler, unless that toddler is nursing a whole lot, probably does not burn 550 calories a day.

That’s pretty cool, if you’re looking at weight loss as one of the benefits of breastfeeding. It’s like doing an aerobics class by sitting on your butt. So why do some people fail to lose weight while breastfeeding, even if their diet is the same as it was before becoming pregnant? Possible culprits:

  • A lack of sleep. Yeah, even if breastfeeding moms get more sleep than moms who bottlefeed, we still don’t get nearly enough. Or we might get enough but it’s broken into nearly-useless chunks. A lack of sleep has a not-so-great effect on hormones and metabolism.
  • Hormones themselves. I’m not even going to attempt to unpack all of the possibilities when it comes to hormones and metabolism and weight loss, but your hormones (speaking about women here) do fluctuate before, during, and after pregnancy, and continue to fluctuate throughout your lives. Here’s a blog post about estrogen and fat distribution in postmenopausal women, which, while not this exact topic, will give you an idea of how hormones can affect weight.
  • Your thyroid might be acting up. Pregnancy and postpartum are common times for a woman’s thyroid gland to get a bit wonky. If you know you have issues with your thyroid, you may need your medication adjusted during or after pregnancy. If you don’t have previous issues, you may develop them; this is something to look into if your milk supply is low for no apparent reason.
  • You’re eating too few calories. It can be difficult for some to get enough food into their bodies to satisfy their basic metabolic needs, let alone what milkmaking requires. Depending upon the person, this may mean a lot of weight loss or none whatsoever. Our bodies try to make sure we survive and (to put it in really basic terms on a very basic level), if they think we’re starving, will conserve calories. Figure out your basal metabolic rate and go from there. You may need more calories than you think.
  • You’re eating more than you think. Hey, it happens. If you’re gaining weight and you don’t want to be, you could count calories. I’m not really in the pro-counting-calories camp, though, and think we could all strive for more normal eating.

The overall points I want to make are:

  • It is not always as easy as calories in-calories out. Our metabolisms change with how much sleep we get, how old we are, our activity levels, and the weight loss/gains we have had in the past. You may need to pull in experts (but unless they’re lactation experts, plug your ears, figuratively, if they have anything to say about that).
  • In terms of milk supply, don’t worry about it. Unless you’re shocking your system by seriously restricting calories or drastically increasing activity level, your body will keep making milk as it was. What is probably a bigger factor in “losing” milk supply if you take up an exercise routine or diet is skipping or shortening feeds, wearing tight clothing long enough that it effectively binds your breasts, or generally just increasing your stress levels.
  • Your body will be different after you have a baby. It will take some time to “bounce back,” or may not bounce back at all. Be gentle to yourself; wait until you’ve recovered from childbirth to even think about diet or exercise. After that, strive for balance between taking care of your desire for weight loss, feeding yourself and your baby well, and taking care of yourself and your family. You may need to come to terms with how your body is different; reading the stories at The Shape of a Mother may lead you to a new perspective.