A longevity researcher is facing backlash for claiming to 'reverse aging.' Scientists say there's no consensus on what it means.

• Harvard researcher Dr. David Sinclair is facing backlash in the longevity community.
• Critics argue that he took claims about "reverse aging" too far, The Wall Street Journal reported.
• Longevity medicine is attracting billions in investment from the world's wealthiest execs.

Harvard researcher Dr. David Sinclair has found himself at the center of controversy within the longevity community.