you will NEVER fast with mk677.. CLEARLY you have done less than zero research on it.. first off, you need carbs with it and cannot go low carb nor fast with it but beyond that it DRASTICALLY increases hunger so even if you could fast with it theoretically, it would literally be the worst choice to go with.. regardless, you have literally done ZERO research which means you have LESS THAN zero business using ANY sort of ped whatsoever.. until you actually do some proper research, the best advice i can give you is to stay a million miles away from any ped whatsoever