I’m a physician and mom exclusively pumping my 2nd baby for 4 months and breastfed my first for 14 months. Not giving you medical advice but personal experience I Have been doing IF (combo of 1200 Omad and 20:4) for 5 months postpartum. Supply has not been affected despite a 60lb weight loss as one comment said, your body will prioritize milk even if you are starving (up to a certain point), otherwise we would not survive as a species. My advice is to track your volume pumping and/or nursing sessions very diligently and if you notice a drop, back off. Let the data guide you. No fasting will not make “toxins” come into your milk. That’s diet culture and “cleanse” mentality, the liver works 24/7 to detoxify xenobiotic substances regardless of your food intake, steatosis and glycogenolysis are affected by fasting but not toxin metabolism in that sense. (Will edit to add total agreement regarding importance of water as another mentioned )
Time restricted feeding shouldn’t really affect supply in itself. The body prioritises the milk. Even actually starving women can produce milk. Dehydration however will affect supply. Keep that in mind, and consider that you get a lot of water from food normally. Stress is another thing that will negatively affect supply, so if fasting is something new to you and in some sense a stressor, it may affect supply that way.
If you are going to do it, start slow. Maybe with 14/10 and gradually build up from there. Don’t go overboard.
I lost all the weight I gained quickly through IF, but don’t be too strict.. if you need to eat, EAT. I could NOT sleep without eating more sometimes. Eat plenty of healthy carbs and sugars. Avoid empty calories if your milk supply is finicky, getting all your nutrients is essential. Nutrients in food > supplementing.
I had an insane milk supply and breastfed for I believe.. 16 months.
How old is your breastfeeding baby? If they’re older than 12 months it really shouldnt matter. I do it and no changes to supply but baby is 2 next month. If your baby is younger than 6 months it could decrease supply, but once you introduce solids your supply will decrease gradually anyway.I also did actually originally have supply issues in the beginning of when I first started breastfeeding.