The bigger story with rapamycin is that the mechanistic target of rapamycin (mTOR) plays an absolutely crucial role in major diseases of modern civilization. One of the ways to inhibit mTOR for free is to simply stop consuming nutrients for extended periods of time.
What is an extended period of time in this context? I happen to consume all my meals within seven hours every day and only drink water in between. Would that help?
(Not doing this for health reasons, it is just a habit.)