I ran across a caloric restriction study being done with human volunteers. It is the CALERIE study (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) being run by Eric Ravussin and Donald Williamson at the Pennington Biomedical Research Center in Baton Rouge, LA.
The study will put human volunteers on a diet with 25% less calories for two years to see of the effects of short term caloric restriction affect the body in ways similar to the effects in animals. In animals, 25% caloric restriction increases lifespan by 20-25% and reduces the incidence of many age-related diseases.
The results should be interesting. I hope they can recruit and keep enough participants on the low cal diet!