Is Deepinder Goyal playing God with Temple?

It's not about religion. Temple is the name of Deepinder Goyal's new wearable — because it sticks to your temple.

And in the last 5-6 days, it has blown up into a full founder vs doctors fight on X.

What is Temple?

- A small, bean-shaped wearable that sticks to the side of your forehead with adhesive patches called Grips
- Priced at ₹85,000 for pre-order. Pre-orders opened Nov 1, deliveries expected in ∼3 months
- Goyal, who stepped down as CEO of Eternal (Zomato + Blinkit parent) to build it full-time, says it tracks two proprietary metrics:
- BrainFlow — relative changes in brain circulation
- Entropy — a 1 to 250 score for how hard your body is working to sustain itself

It's tied to his Gravity Ageing Hypothesis — the idea that gravity's long-term pull on blood circulation contributes to brain ageing. Goyal himself now calls this a hypothesis, not an established theory.

Goyal insists: "Temple is a fitness tracker, and wellness device. We are not a medical device" and that it hasn't been clinically validated.

Why are doctors angry?

The core scientific question: Can a sensor outside the skull measure blood flow inside the brain?

Temple uses PPG — shining light into tissue to detect blood volume changes. Its sensors sit near the superficial temporal artery, which supplies the scalp and face. The brain gets blood mainly through the internal carotid and vertebral arteries.

Doctors, led by hepatologist Dr Cyriac Abby Philips, aka The Liver Doc, say that's the problem:

> Philips called Temple "the biggest health scam and wellness fraud in India" and said it can only measure blood flow and flushing to the face, with "absolutely NOTHING to do with" the brain.

He also listed 4 gaps: BrainFlow, Entropy Score, heart-rate accuracy, and longevity insights, and said customer experiences can't substitute for independent validation.

Other doctors echoed it. Neurologist Dr Sudhir Kumar said the key question is not whether the signal changes with exercise or meditation, but "whether it reliably measures what it claims to measure, whether it adds information beyond existing metrics, and whether acting on it improves health outcomes".

They also point out Temple's studies so far are funded, run and analysed by Temple itself, not peer-reviewed. One preprint claimed ∼0.8 correlation with a major brain artery, but critics say that's not enough for a ₹85,000 product.

Earlier this year, an AIIMS Delhi physician had already called it a "fancy toy" after Goyal wore it on Raj Shamani's podcast.

How did Goyal respond?

On Nov 5, he posted a 7-point note titled "Dear Concerned Indian Doctors" ending with "If not, keep raging."

His arguments:

1. Not a scam because of returns: "We have 14-day, no-questions-asked returns (which even Apple doesn't offer in India). If the product doesn't work, it fails out of the gate"
2. Money: "We have already spent $30m building Temple, $20m out of which is my own money. Selling a few thousand devices recovers a small fraction of this investment. A scam that pays nothing is not a scam anyone would run"
3. Precedent: Whoop launched in 2015 and published validation years later. Temple will release preprints first, then peer-reviewed papers.
4. Future features: "The most ground breaking features in Temple are not even public yet. And some of them, thankfully, have nothing to do with doctors"

Philips hit back, calling it a "word salad" with "no real evidence or proof" that it can measure brain flow from a superficial artery.

Then came the apology

On Nov 6, Goyal walked it back:

> "I should not have bucketed all Indian doctors into one single box... All my emotion last night was directed at a few influencer doctors, who are more influencers than doctors."

He said those doctors didn't read the research and were piling on for views, while he works with many doctors — including his elder brother, who is one.

So where does it stand?Unresolved.

Goyal says: Judge it when it ships in early 2027, independent studies will come, it's wellness not medical.

Doctors say: Don't sell ₹85,000 brain-health claims before independent, peer-reviewed validation. A return policy is not proof.

It's become the classic India tech fight: founder innovation vs medical evidence — played out in public, on X, in the middle of Diwali week.

A sensible view is in the middle — and it's boring, which is why no one is posting it on X.

Don't call it a scam. Don't call it a breakthrough. Call it what it actually is right now: an expensive, unvalidated wellness experiment.

How to think about it clearly?

The idea is not crazy. The claim is ahead of the proof.

Measuring blood flow near the temple with light — PPG — is real science. Your smartwatch does it on your wrist.

The jump is: scalp blood flow = brain blood flow.

That's plausible as a correlation, not proven as a measurement. The brain gets blood from deep arteries. The temple sensor sits over a superficial artery that feeds skin and face. They move together sometimes, they don't move together always.

Temple's own preprint claiming ∼0.8 correlation with a major brain artery is interesting. It's also funded, run, and analysed by Temple itself, and not yet peer-reviewed. In science, that means: promising, not proven.

Goyal is right that Whoop, Oura, Apple all launched before full validation. He's also wrong to use that as a shield. Those products measured heart rate and sleep — low-stakes. Temple is selling "BrainFlow" and "Entropy" and "Ageing" — high-stakes words that sound medical, even if the fine print says "wellness, not medical."

The burden of proof is on the seller, not the doctors.

Doctors are not being killjoys. Their job is to ask: If I act on this number, will I be healthier? If a 45-year-old sees a low BrainFlow score and panics, or a high score and ignores real symptoms, that's harm.

A 14-day return policy is good consumer policy. It is not scientific validation. You can return a product that feels useless. You can't return a false sense of security.

Similarly, "$30 million spent, $20 million of my own" proves sincerity. It does not prove accuracy. Theranos also spent a lot of its founder's money.

The price changes the ethics

If Temple was ₹8,500, this would be a fun gadget debate.

At ₹85,000, it's a health purchase for most Indians. That's more than most families spend on health in a year. At that price, "trust me, preprints coming" is not enough. You need independent labs, independent participants, and data showing it adds something beyond a ₹5,000 smartwatch that already tracks HRV, sleep, and stress.

Goyal's own apology got this right: you can't bucket all doctors as "influencer doctors." The Liver Doc is abrasive, but the question he asked is the right one: Show us you measure what you claim to measure.

So what should you actually do?

If you are a consumer, use this checklist:

- Don't buy it to diagnose anything. Not brain ageing, not stroke risk, not dementia, not "longevity." Temple itself says it is not a medical device.
- Don't buy it on pre-order hype. Wait for 3 things: 1) Independent, peer-reviewed validation, 2) Real users using it for 60-90 days, not launch-day reviews, 3) Clear explanation of what Entropy actually changes in your daily behaviour.
- Do be excited that an Indian founder is trying hardware. India almost never does hard tech consumer hardware. That ambition deserves respect, not mockery.
- Do hold him to his own promise. Goyal said: "Each of our claims is easily verifiable by individuals and institutions alike, and you will see a lot of independent studies come up." Good. Let those studies come before we call it a breakthrough.

In my view the most sensible view is this:Temple might become a useful wellness tool. Right now, it is a hypothesis with a price tag.

Buy hypotheses with curiosity, not with ₹85,000 and your health anxiety.

Wait. Watch. Let the data arrive.