Doctors question Deepinder Goyal's Temple wearable, sold after testing on 23 people

Deepinder Goyal, founder of Eternal, the parent company of Zomato and Blinkit, is in a controversy over a new health-tech device. He has launched a wearable called Temple, and prominent doctors and medical experts in the country have raised serious questions about its health claims.

Temple is a very small, pill-shaped device. It is attached to the temples on both sides of the head with a special adhesive patch. Unlike an ordinary smartwatch or fitness band, it is not described as being limited to tracking steps, sleep or simple heart rate.

The company's biggest claim is that the device can accurately track blood flow inside the brain and related changes. It also measures a metric called "entropy", which indicates how much energy the body is spending to keep itself cool. Goyal has linked the technology to his "gravity ageing hypothesis". According to him, the long-term effect of gravity on the body affects blood circulation and is directly related to the ageing of the brain.

These technical claims are at the centre of the dispute. The main question from medical experts is how a small sensor placed on the surface of the skin can accurately measure blood flow in the highly complex interior of the brain. They say blood flow in the vessels of the face or outer skin and blood flow inside the brain are two different things. Even though there are blood vessels near the temples, signals from there do not necessarily reflect the internal condition of the brain. Another concern is that the company tested the device on only 23 people and put it straight on sale. Sales have begun without any large clinical trial data or independent peer-reviewed report being released, which has caused anger in the medical community.

Hepatologist Dr Cyriac Abby Philips, known on social media as "The Liver Doc", has raised the sharpest objection. He has called it "India's biggest health scam and wellness fraud". According to him, the device is not measuring blood flow in the brain but recording flushing or superficial circulation in the facial skin.

Dr Biplab Das, director of neurology and interventional neuroradiology at Batra Hospital, said such wearable gadgets can create needless fear or false reassurance in users. According to him, if a person relies too heavily on wrong or misleading data from the device, they may ignore real symptoms of serious illness. He also said it is wrong to lend medical credibility to such devices without independent clinical certification. He added that making claims on the basis of a preprint alone, without a large independent scientific study or peer review, is not appropriate.

In response to the criticism, Goyal defended his project in a long post on X (formerly Twitter). He said about $30 million (roughly Rs 250 crore) has been spent on it, of which $20 million he put in from his own pocket. He also said he decided to step down as CEO of Eternal for the sake of this ambitious project.

Goyal cited the fitness brand WHOOP. According to him, WHOOP launched its band in 2015, but its scientific research was published years later. Goyal said the company is fully ready for scientific testing of Temple and that preprints will be released soon. A 14-day "no-questions-asked" return policy has also been offered to give customers confidence.

In a post dated November 2, 2026, Goyal referred to a heart rate benchmarking study. According to him, in zones 4 and 5, Temple's heart rate tracking was more accurate than a standard-wear ECG chest strap. He also wrote that more independent validations are under way and urged sceptics to wait before buying.