Well, I wouldn't want to give advice regarding calories to a BFing mom, but here's what one La Leche leader said to me:
"In third world countries, nursing moms are often calorie restricted because of lack of food. They continue to nurse their babies just fine as long as they are well hydrated."
Not sure if this is true, it's just what she told me.
As for me, I lose weight most easily with an LC/Paleo-type diet. BUT I can't handle the carb flu right now. (My 1-month-old is BFing.) So I basically just try to stick to grain-free, natural carbs (potatoes, starchy veggies, stuff like that).
I have been (not intentionally) IFing by skipping breakfast most days, simply because I just don't have time to eat (and don't think about eating either). This baby is my third kid, too, and all of my kids are age 5 or younger. I slurp down black coffee until about noon, then eat lunch. However, I don't wake up until 8 or 9 am, so I guess it's more a late breakfast. Anyway, it hasn't affected my milk supply, but then I've always had an abundant supply.