I weigh about 240lbs rn with a lot of built up muscle from working out for years but I also have gained some fat. How would you recommend I fast to optimize fat burn and keep as much muscle and as possible ?
Taking a walk, 30m-1hr, has been proven to help slow lose to nearly nothing over fasts that last a week. Doing literally anything will keep your body from canablising muscle since you are using it. Many body builders fast 48hrs for the supposed hgh increase.