- Doctors question Temple wearable's brain blood flow claims.
- Deepinder Goyal defends device as fitness, not medical.
- Controversy over scientific validation and high price.
Zomato co-founder Deepinder Goyal's latest venture, Temple, the wearable startup, has been under fire as the medical fraternity questioned the scientific evidence. Temple's claims around brain blood flow, a proprietary physiological metric and insights into ageing drew severe criticism from a section of doctors.
The controversy has escalated into a public exchange between the Goyal and sections of the medical community, with prominent hepatologist Cyriac Abby Philips, popularly known as TheLiverDoc, accusing the company of making scientifically unsupported claims.
What Is The Controversy?
At the heart of the dispute is whether a wearable attached to the side of the forehead can reliably measure changes in blood circulation inside the brain, and whether the proprietary metrics it generates have been scientifically validated to support the broader health and longevity insights associated with the product.
What Are Doctors' Concerns?
The central objection is anatomical. Temple uses optical sensing (photoplethysmography) near the superficial temporal artery, which supplies the scalp and face.
Doctors, however, said the brain is supplied mainly through the internal carotid and vertebral arteries. According to doctors, scalp circulation can shift with exercise or temperature without reflecting flow inside the brain, and that one measurement site may not represent the whole brain.
Recommended For You
Hepatologist Dr Cyriac Abby Philips has also called the product a "scam" and accused the company of misleading buyers. "His scam was caught in January 2026 after which he started calling out doctors rudely at that time also. He mentioned he will show the science of brain flow, Entropy assessment by the device at the time," Philips said in an X post.
Good morning. Deepinder Goyal is a liar. It was always about the brain, even though he now claims it was not. His scam was caught in January 2026 after which he started calling out doctors rudely at that time also. He mentioned he will show the science of brain flow, Entropy assessment by the device at the time. A few months later, he showed screen shots of what he calls the device can measure, which others cannot, called Entropy - screen shots from his own team - which can be easily made using Claude. Still no working device based proof. Zero evidence of parameters measured to showcase Entropy. Fast forward 10 months later, November 2026, he is still making the same claims, no new evidence, no real data other than what his company wrote on the website. The company website (https://t.co/GXfRVjQf9x) still promotes the device for cognitive health, brain tracking and entropy. I and other clinical-scientists HAVE gone through everyy detail of science published on Temple here https://t.co/xGJN0H7vcG and none of it proves this device can measure what it claims. Yes, heart rate and blood flow to the scalp from the temporal artery. But nothing more - because there is no data. Temple is a beautiful scam, built over the years using influencer network, paid celebrity collaboration (obviously all of these will be denied) and a false marketing to convince people that this device does more than any other device. It does not do anything beyond the basics. This is a global scam and the government regulators must assess the claims made before this becomes a circus show for the West. Guys like MKBHD and Mrwhosetheboss who can really do work on this will rip it apart - so go give them the device and not your local chamcha influencers.
— TheLiverDoc™ (@theliverdoc) November 9, 2026
Goyal has answered his critics on X. On motive and money, he said Temple has spent USD 30 million, including USD 20 million of his own. He argued that a scam would not recover a fraction of that from a few thousand sales.
Deepinder Goyal's Explanation
Goyal has pushed back, defending the technology, questioning the credentials and motives of some critics and insisting that Temple is "a fitness tracker and wellness device" and that it is "not a medical device". He asserted that the metrics still await clinical validation.
Hello everyone. Happy Diwali! Thank you for your criticism, your support and your time over the last two days. Gives me much needed clarity on what we need to explain better: 1. Temple is not made for India. It’s made for the world. Please check pricing. We don’t expect any more than 1% of Temples being sold in India. 2. If you are upset that the pricing is too high, I am sorry. There’s a lot of work that went into Temple, and we priced it at what we think it’s worth. If you think its overpriced, you can wait for user reviews to decide if its worth your money. 3. Please do not support us because we are an Indian startup. We want to compete globally. We don’t need/want nationalist support. Support us if you want to support early innovation, which could help you live a better life, and will continue to add more proof to its science over the years. 4. There are different audiences which buy products at various levels of proof. Proof goes from whitepaper -> pre-print -> peer reviewed. You are free to sit on the fence until peer reviewed proof arrives. You are free to not believe it even then. Nobody is forcing you to buy. Making announcements is our right; and if we overclaim anywhere, we will inevitably fall into regulatory trouble everywhere in the world. 5. We didn’t make any medical claim. Doctors primarily see things from a medical lens, so they see every claim as a medical claim. I repeat – Temple is strictly a fitness + AI device, and we've made no medical claims. Temple is not proven to diagnose or prevent any disease. It doesn't do anything which replaces the need for you to see a doctor. 6. The main point of Temple is NOT Brain Flow. That’s what we just started Temple for, and studies on Brain Flow are the first ones getting out. 7. The main point of Temple is Entropy (I shared the HomeScreen of Temple three months ago with Entropy as the main thing). Our emails to our waitlisted users only talk about Entropy. We haven’t published anything on Entropy yet. We will. If you want to buy Temple before that, please do. If you don’t want to, don’t. 8. Roomdeaf AI is an expansion of the device’s capabilities, and our vision for Temple. It is not a pivot. 9. Social media is not the regulator for Temple. Wherever we need regulatory clearances, we will have them before we make any claim needing them. 10. I will post a detailed note on how we calculate Brain Flow, its uses, and most importantly, its limitations in a bit (tomorrow).
— Deepinder Goyal (@deepigoyal) November 8, 2026
Temple, according to Goyal, is designed to continuously track physiological signals using sensors placed on the forehead.
Its two principal proprietary measurements are BrainFlow and Entropy. BrainFlow is intended to track relative changes in blood circulation associated with the brain. Goyal has described the device as capable of monitoring such changes continuously, rather than relying on occasional measurements in clinical settings.
Entropy, which Goyal has now identified as the product''s principal focus, is a proprietary score intended to indicate how hard the body is working to sustain itself. The score ranges from 1 to 250, with lower readings associated with deeper rest and higher readings with greater physiological exertion.
Goyal Defends High Price
The device, which uses optical sensors and is worn near the temple, opened for pre-orders in India on November 1 at Rs 85,000. Many questioned the high price of the device. On pricing, Goyal said if the Rs 85,000 price tag has upset people, he was sorry.
"There's a lot of work that went into Temple, and we priced it at what we think it's worth. If you think it's overpriced, you can wait for user reviews to decide if it's worth your money," Goyal said. He also said the product is initially not for Indian consumers, as he expects only 1% sales in the country.
(With PTI Inputs)