A wearable that promises insights into brain health, a high-profile entrepreneur backing it and a growing list of doctors questioning its science. Deepinder Goyal's latest venture, Temple, has found itself at the centre of a heated debate over how much consumers should trust health-related claims before independent scientific validation is available.
The controversy has brought Goyal, founder of Zomato's parent company Eternal, face-to-face with sections of the medical community, with hepatologist Dr Cyriac Abby Philips, popularly known as The Liver Doc, emerging as one of the most vocal critics.
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Temple is a pill-shaped wearable designed to sit on the side of the head, near the temple. Priced at Rs 85,000, the device is being developed to monitor cerebral blood flow and provide insights into brain health, performance and the body's broader physiological condition.
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According to the company, it also measures a parameter called 'Entropy', which indicates how hard the body is working to dissipate heat. Its readings are intended to help users understand their recovery, stress and overall physical condition.
The device is also linked to Goyal's Gravity Ageing Hypothesis, which explores whether gravity's long-term impact on blood circulation could contribute to ageing, particularly in the brain.
Why Are Doctors Questioning Temple?
The central concern is whether a sensor placed outside the skull can reliably measure blood flow to the brain, rather than simply detecting changes in blood circulation near the skin.
Dr Philips has questioned the scientific basis of Temple's claims, arguing that the available research does not establish that the device can measure cerebral blood flow or accurately interpret entropy.
Deepu: Guys! We made a wearable that can track your brain activity in real time! Just place it on your temple. Doctors: Wow! Damn cool bro. Show us how it works! We are interested! Deepu: Ehhh...why you raging!!?? It's actually a fitness tracker. Doctors: Oh! That's ok. We anyway need one from India! All the ones now are by the West! Go India! How does it stack up to the current cheaper validated wearables though? Deepu:
— TheLiverDoc™ (@theliverdoc) November 6, 2026
Philips has questioned the scientific basis of Temple's claims, arguing that the available research does not establish that the device can measure cerebral blood flow or accurately interpret entropy.
Responding to Goyal's defence of the wearable, Philips wrote on X: "As expected, he has written a word salad. This man has provided no real evidence or proof that his device, which he is selling for Rs 85,000 can measure and interpret brain flow from a superficial artery."
He further alleged that the device could only measure blood flow and flushing near the face and had "absolutely NOTHING to do with the brain" as claimed.
In another post, Philips listed four areas where he believes Temple lacks adequate evidence: BrainFlow, Entropy Score, heart rate accuracy and longevity insights. He argued that customer experiences and promises of future research cannot substitute for independent scientific validation.
Addressing what he described as the "rage" against Temple, Goyal posted a seven-point response to "concerned Indian doctors" on X.
He said the company had already spent $30 million developing the device, including $20 million from his personal funds. Goyal also pointed to Temple's 14-day, no-questions-asked return policy, arguing that customers would quickly reject the product if it failed to deliver.
Defending the development timeline, he cited Whoop, which launched its fitness band in 2015, with published validation studies following years later. Goyal said Temple's pre-prints were forthcoming and that independent studies would follow once the device became widely available.
ALSO READ: 'If Not, Keep Raging': Deepinder Goyal's 7-Point Reply To Doctors Calling Temple A Scam
He also clarified in another response that Temple is a fitness and wellness wearable, not a medical device, adding that clinical validation would be communicated if any of its metrics were validated for clinical use.
His closing message to critics was pointed: "If not, keep raging."
According to multiple media reports, Temple's pre-orders are open in India at Rs 85,000, with six colour options available. The first device is scheduled to ship in early 2027.
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