The secret to longevity is in stimulating autophagia while simultaneously boosting HGH and other hormones. Aging is just a matter of your cells getting old or damaged faster than your body can break them down and replace them with new cells. Anything you do to speed up the degradation of cells (consuming alcohol, for instance) is going to age you faster. Anything you can do to speed up the rate at which your body breaks down old, damaged, and per-cancerous cells (like fasting for more than a day) is going to help slow the process down. If you slow it down enough, and boost the synthesis of new cells enough, then you have the solution to at least halt aging.
Nobody has yet figured out a method to actually completely invert the process (where you clear out all the old cells and regenerate them) past adolescence. If you do that, then you don't just halt aging, you can reverse it.