Yes, breastfeeding does help you lose weight, and keep it off, according to studies. For maximum benefit you need to do it for at least six months, but even three months of exclusive breastfeeding has been shown to promote postpartum weight loss.
One large, long-term UK study published in the International Journal of Obesity found that on average for every six months a mom breastfed she had an average BMI of one percent less, even decades after she gave birth. Which is pretty significant — the equivalent of a 5′ 1″ woman who was 150 pounds pre-pregnancy breastfeeding for 18 months and getting down to 130 pounds and staying there. A later study found that it’s particularly helpful for weight loss for obese women.
For the first six months postpartum, the same hormone that stimulates milk production also cues your body to hang on to extra fat, and also stimulates your appetite. Breastfeeding in the first few months also involves a lot of sitting, which means burning fewer calories. So while it’s true that breastfeeding burns 200-500 calories a day, increased appetite plus hormonal effects and a lack of activity mean you probably won’t see a weight-loss benefit from all of that metabolic activity.
But at about six months postpartum if you’re still nursing a few important things will change. As baby starts solids you’ll still be burning about 200-500 calories a day producing milk, but your body will naturally start to let go of those fat stores. Your appetite will go back to normal and with fewer nursing sessions you’ll be able to be more active, too.
For more on Breastfeeding, check out our Breastfeeding FAQ