Should probably wait until they are weened first, but, if you WANT to ween them this way, I guess you could lol. Kudos for breastfeeding them this long, good mama. If they weren’t a toddler already and eating other foods like you say, obviously it would be “no way”. :)
I don’t do snake diet but I’ve been intermittent fasting for 5 months (since she was 4 months old) and I exclusively BF. No issues. But I eat in my TDEE unlike snake diet so my body isn’t losing any nutrition.