What is Temple? Inside Deepinder Goyal’s ambitious brain-health wearable

When Deepinder Goyal announced on January 21 that he would step down as chief executive officer of Eternal and move into a vice chairman role, the Zomato founder framed the transition as a deliberate shift toward risk.

The new role, Goyal said in a post on X, would give him room to explore “new ideas that involve significantly higher-risk exploration and experimentation”.  

That message immediately set off speculation across India’s tech and startup circles. At the centre of it: a research-grade wearable device known as Temple, an ambitious project that Goyal has personally funded.

A $25 million bet on the human brain

Temple is not a typical consumer wearable. Goyal has reportedly invested more than $25 million (around Rs 225 crore) of his own capital into building and studying the device.

The prototype first entered public view after Goyal appeared wearing it on entrepreneur Raj Shamani’s popular YouTube show Figuring Out, triggering widespread curiosity and scrutiny online.

Temple is designed to monitor brain health by tracking cerebral blood flow (CBF) in real time, a metric that reflects how efficiently blood circulates through the brain. The data could offer new insights into ageing, cognition and long-term neurological performance.

The device is closely tied to what Goyal calls the Gravity Ageing Hypothesis, a theory that gravity gradually pulls blood downward in the body over a lifetime, making it harder for circulation to move upward toward the brain. According to the hypothesis, this reduced blood flow contributes to accelerated biological ageing and cognitive decline.

Temple is intended to measure these circulation patterns continuously, potentially enabling new forms of preventive brain health monitoring.

Hype meets scepticism

The project’s growing visibility has also attracted scepticism from doctors and researchers, many of whom have questioned the lack of published clinical validation behind the science.

Goyal, however, clarified on X, saying, “We haven’t made any public commercial announcements about Temple yet. We haven’t released any official device benchmarking data.” 

He added that the research remains ongoing and that it would take months before the company even considers making the wearable public.