Serious question - why do you feel 0 calorie beverages like the ones above need to be avoided?
2 reasons
1. anything that is not water even if zero calorie your stomach has to break the down enzymes. so you want to give your stomach/body 100% day off. drink only water. i love bcaas, diet soda, coffee (all the zero calorie stuff) but i cut it out when I fast
2. also i am a firm believer in all or none. if you drink BCAAs when you fast... why not a pickle? they are only 5 calories, or a few chocolate chips ? so nothing but water. keeps you honest
there are many ways to fast, I have a large frame (midwest/german) and i am a firm believer in it to really lean up/trim down. but i only support the 24 hour fast or ideally the 36 hour fast for me. if you are a big dude - fasting is an easy way to get get in great shape without really doing much different. plus it saves you $100+ a month too..
it can really help with digestive problems which ive finally sorted out.
anyone asks me how to loose weight/get their health on track? eat a moderately clean diet and do 36 hour weekly fast.