Yeah, I've heard of this. I don't think there's any science behind suggesting that squash is a "hormone producing food" or that women need to eat high carb foods (like potatoes) during their period. However, for some women, upping your red meat intake makes scientific sense.

I think most women who have tended to big hormonal variations (and all the accompanying effects) during their periods find this evens out while they're on low carb and I wouldn't think upping your carb intake would have a positive overall effect.

But if your instinct is telling you not to fast, then that's a great reason not to.