Also there was a recent article that made it to the front page of HN talking about a positive study of intermittent fasting's longetivity-related benefits - which is probably a closely related or identical phenomenon (my guess).
[1] http://www.nature.com/ncomms/2014/140401/ncomms4557/full/nco...
To our knowledge, only one study investigated the effects of long-term CR (with a diet of reasonable quality) on health and longevity in nonobese humans and a control group (24). This study was conducted in 120 men, of whom 60 were randomly assigned to the control group and 60 to the calorie-restricted group. The control group was fed ≈9600 kJ/d. Calorie-restricted subjects received 1 L milk and 500 g fruit every other day, which led to an overall mean energy intake of ≈6300 kJ/d (or a 35% restriction from the intake of the control group). This regimen was implemented for 3 y. Stunkard (25) reanalyzed these data and reported less time in the infirmary (123 compared with 219 d) and a nonsignificant difference in the death rate (6 compared with 13 deaths) in calorie-restricted subjects than in control subjects, respectively, which suggests that chronic CR may prolong life span in humans.
It certainly has documented effects on weight, blood pressure, insulin, etc. What you mean to say is that while it's been amply proven in lower species to extend lifespan, lifespan extension has not been proven in humans as of now.
Ever study I've read about has shown that while calorie restriction works in mice, it has no effect in humans.