Aging is a side effect of metabolism and imperfect reparation mechanisms, or totally missing repairing processes.
Metabolism it most important thing for a living organism, with out it the organism die. There is a minimal required level of metabolism, if the body processes decrease under some limits the organism will die. Because of this we can not slow down the metabolism and aging more than probably 30-40%. Slowing down some metabolic processes will also increase the risk of other death causes and the final result could be not so impressive.
This is why slowing sown aging is a dead ended strategy … it will add a 30-40% increase in longevity but the end result is still the same incurable aging diseases: Diabetes, Cancer, Cardiovascular Diseases, Nero-Muscular Diseases …
And keep in mind some people are already benefiting from a life expansion because of their natural lifestyle, diet or genetics so the maximum lifespan will probably not increase too much.
What we really need is Damage Repair and reverting the organism to a young full state, or at least removing and reversing the accumulation of changes which causes pathological diseases.
Most of the Diet tricks and Antiaging Scientific Breakthroughs and research (IGF1, Revastrol ) are nothing more than methods of slowing down aging, with the effect of delaying the pain of aging, (allowing multiple pathologies to evolve) leading to rectangularization of mortality, a smaller period of disability but leading to the same result chronic Progressive diseases, disability and death