Deepinder Goyal, best known for co-founding Eternal, which houses Zomato, is under fire from Indian doctors for his new 85,000 rupees ($907) wellness device, Temple.
While India's cricket captain Shubman Gill has worn it, medical experts are skeptical about its claim to track brain blood flow and want tighter rules.
Prominent Indian hepatologist Cyriac Philips, known as "TheLiverDoc," even called it a "health scam," and pediatrician and nephrologist Dr. Sanjeev Bagai says Temple is a "gimmick" and said it had "no formal approval or clearance."
Temple says not a medical device
Temple has pushed back against the criticism, saying its BrainFlow and Entropy features are innovative and more research is coming.
Goyal clarified that Temple isn't meant for medical use. It's just a wellness gadget.
For now, the government hasn't weighed in, but the debate highlights bigger questions about how high-tech health wearables should be regulated.