David Sinclair, 40
(SUSAN DESTEFANO—HARVARD MEDICAL SCHOOL)
Professor of pathology, Harvard Medical School
What he does: Has taken resveratrol, a compound found in the skin of red grapes, since 2003. He has even gotten his wife and parents to follow suit.
Why: Resveratrol may activate a family of longevity-related enzymes. Sinclair gave up a calorie-restricted diet, which may work similarly, after a week. "It just made life seem longer," he says.