Does breastfeeding actually help you lose weight?

I do see myself losing abit of weight, even though I eat a lot and tend to be hungry in the wee hour. But I do not gain any weight ( that's the best part about breast feeding isn't it ? ) You don't see the weight lost immediately ! It's actually rather slow, I've breast fed my girl for 1year, have not reach my pre-pregnancy weight yet but lost a total of 5-6kg through out the year without any diet