In a nutshell...
Rez does lots of different things but one of the primary actions is to shut off all the gene triggers associated with hypercaloric diets. These gene triggers are intimately involved in the aging process and therefore make one more prone to age-related diseases such as atherosclerosis, cancer brain degeneration etc.
Shutting them down allows people like us to continue to eat a lot to maintain our physiques but metabolically and genetically the body is closer to a state of hypocalorism which is very well known to enhance lifespan in human and animal models.
On the whole, Americans are developing a shorter lifespan, despite our elevated living conditions, due largely to caloric excess and heavy reliance on low GI carbs/high saturated fat intake.
I notice, and I'm sure many of you do, that when bulking I feel slow and lethargic. Cutting, I feel a lot zippier mentally and physically. Perhaps high doses of Rez can give us the benefits of cutting/hypocaloric situations even when living hypercaloric lifestyle.