There aren’t loads of studies about dieting while breastfeeding, as it’s probably unethical to starve some new mums just to see what happens! However, there is a study that compared the nutrition of breastmilk from mums on a comparatively nutritionally poor African diet to breastmilk from mums on a typical comparatively generous western diet. The nutritional content of the milk was practically identical. Obviously you need to keep well hydrated, but what you clearly don’t need to do is eat to maintain your current weight. In pregnancy, your body lays down fat to be used during nursing when (historically at least) you were likely to use more energy than you can eat – so the whole process is designed for you to lose weight while nursing. I did 4:3 while nursing from very early on. I did research into the subject as I was massively overweight and very unhappy after having my son, and I really needed to lose the weight – but would only have done so if it was safe. I lost 5 stone in my son’s first year. He’s 2 now, still nursing! It didn’t affect my milk or him. It’s not a popular idea though, so be prepared for all your friends to tell you it’s dangerous, silly, selfish etc and that you need to replace the calories you use nursing by having extra food. You don’t. Just be sensible and drink well.

I’d echo what 2fast says about breastfeeding not being a barrier to losing weight, but there are a couple of considerations worth mentioning. Firstly, how is breastfeeding going for you? If it’s established and you’re used to fluctuations in your baby’s feeding from time to time, fasting could work. Extra water is really important, both on the fast day and the day before. It might be worth starting off with 5:2 for a few weeks and getting a little more exercise just to see you things go, before stepping it up to 4:3 to speed up the results.

Good luck, and let us know how you get on.

My baby is older, nearly a year, I try and keep to the 500 but if I go up to 600 I don’t worry too much, if my baby was younger and if I felt like I needed to up my cals on a fast day then I would