Not Just About Temple: India's Wearable Impasse

From developing new health metrics to navigating clinical trials and regulatory approvals, Temple's journey offers a glimpse into the challenges and opportunities facing India's next wave of wearable startups

"There is no established playbook for making wearables in India. If you have the capital, you can set up a team, hire a bunch of researchers and scientists and come up with a product and even start selling it," a California-based Indian founder of a wearable startup told us this week.

The heated and contentious battle on X over Temple has brought out a lot into the open. A lot has been said and written about Temple this month, and who's right and who's wrong. What has gone unanswered in the cacophony is what it takes to actually launch a health or fitness tracking wearable that's made in India.

Where do founders turn when they need their hypothesis tested? Which agencies are the most approachable and how much red tape can one expect? These questions are not just about Temple. It's about any new device that's being launched in India, whether it is looking to track blood flow to the brain or it is just a heart rate or fitness monitor.

The distinction matters in a market where wearable manufacturers can build and sell products that track physiological parameters without necessarily undergoing the clinical validation expected of medical devices.

For India's wearable industry, the debate has exposed gaps in how companies develop, validate and market products that make health-related claims or even basic activity tracking. But first, let's see where Temple stands before diving deeper into the ecosystem of health wearables.

Temple's Bet On Something New

Deepinder Goyal launched Temple with a core proposition of tracking blood flow to the brain and entropy. The company set out to create two new metrics that give users something their smartwatches could never.

Firstly, BrainFlow is said to track relative changes in the blood flow to the brain during everyday activity. On the other hand, Goyal has described Entropy as a measure of how hard the body works to shed heat.

The company's website says the metric captures the body's load across thermal, immune, digestive, cognitive, emotional, pharmacological, postural, reproductive and recovery systems. However, research papers uploaded on its website clearly state that Temple cannot directly measure cerebral blood flow.

In response to Inc42's questions about how these are measured, Temple said the Brain Flow Index is a relative index derived from optical signals collected at the temple. The company said the index rose and fell alongside blood-flow velocity in the middle cerebral artery, a major artery in the brain, as measured through transcranial Doppler ultrasound.

Temple said the metric currently has two applications in its fitness app. It helps users compare the intensity of their cardio sessions and sends prompts to move when their Brain Flow Index drops during long periods of sitting.

Unlike heart rate or sleep tracking, which have been part of consumer wearables for years, Entropy is being positioned as a new physiological metric. Its scientific validity will depend on whether the underlying signals can reliably measure what the company claims.

The fact that Temple is broaching new territory with these metrics is what has set alarm bells ringing. Founders we spoke to say most wearables already have algorithms available for the heart rate and sleep tracking that have been improved and enhanced over the years since the first such devices came about.

"The real work comes when you develop a new tracker or establish a new biomarker or a new benchmark for measuring something new," the founder quoted at the beginning said, adding that specialised algorithms need research papers and validation.

This is why there's so much scepticism around Temple in the medical fraternity, with many doctors accusing the company of pushing a product without adequate backing.

Temple's research page lists multiple studies examining its BrainFlow technology, including a study involving 23 healthy adults that compared its reading with transcranial Doppler (TCD), a clinical technique used to measure blood-flow velocity in major brain arteries.

Another study compared Temple's BrainFlow readings with near infrared spectroscopy (NIRS), a technique that can distinguish blood volume changes in the brain from those in the scalp.

The company says it has partnered with academic institutions across the world to study additional and more diverse groups of people, with further validation studies underway.

Both studies are listed as being under peer review. A Temple spokesperson told Inc42 that validation work on Entropy is in its final stages and that it plans to publish the findings soon.

Of Preprints And Peer Reviews

After much criticism, on November 8, Goyal acknowledged the gap between the peer reviews, the studies and the launch of the devices, adding that the research on Entropy would be published soon. He also said BrainFlow was not the primary proposition behind Temple, but the starting point for its research.

In an earlier November 5 post, Goyal said preprints would precede peer-reviewed publication and that further validation would continue as the product reached users.

The distinction between publishing a white paper, uploading a preprint and completing peer review matters. But what do these words mean for founders who are entering the space fresh?

Simply put, a white paper and a preprint make research available for public scrutiny, while peer review brings an independent assessment of the methodology, findings and conclusions.

A second founder, an early stage entrepreneur building neuro-centric wearables, said credible validation requires controlled trials. "Generally, you need a double-blind test, a control group and a placebo group. The bare minimum that is respectable enough is 90 people."

However, there is no fixed requirement on the number of participants, they said when we asked whether 23 people is a large enough sample size for Temple's study. "You can do it for 10 people. Nothing is a mandate. But is it respectable to have a big test group? Maybe," the founder added.

We were also told that publishing research papers is not compulsory either, but it helps establish credibility. At the moment, no regulations govern the release of such papers along with a product. "It's not necessary to put out your research papers, but it is something that people demand for credibility," the second founder added.

Plus, getting a study peer-reviewed is not easy. Founders need to find the right testing bodies to conduct reviews. This comes along with a growing demand for independent validation from investors and others who want to partner with the startup. "Third-party trials are what most wearables get asked for, by investors and consumers. Even doctors are asking for them," the founder added.

For early stage startups, the cost of conducting larger studies can be a huge constraint.

In their case, a study comprising just 100 subjects cost the startup around ₹15 Lakh, which the company claims is a lot at the early stage especially when the product has already been built. Most of the funds raised are depleted by the time the startup reaches the testing stage.

Is Temple A Medical Device?

The debate also raises questions about how India's regulatory framework applies to wearable devices.

Under the Medical Devices Rules, 2017, a product's classification depends on its intended purpose and the function it is designed to perform.

The Central Drugs Standard Control Organisation (CDSCO) regulates devices intended for purposes such as diagnosing, preventing, monitoring or treating diseases, as well as investigating or modifying physiological processes.

Simply calling a product a fitness or wellness tracker does not settle its regulatory classification. Its intended use, advertised claims and actual functionality matter when it comes to clearances.

Some well-known doctors in the country, who are sceptical of Temple claims, said the device's capabilities are not backed by peer-reviewed research. Hence, they have called for the device to come under the purview of medical regulators.

However, Goyal has repeatedly maintained that Temple is not a medical device and is not intended to diagnose or prevent any diseases. He has also said that the company will obtain regulatory clearance wherever required before making claims that need it.

Responding to Inc42, a Temple spokesperson said the device does not diagnose, treat, cure, mitigate or prevent any disease, and makes no claims about any medical condition.

The company argued that under Indian law, a product is classified as a medical device based on its manufacturer's intended purpose. It also cited CDSCO's 2026 guidance on medical-device software, which says software intended for general wellness, without any reference to disease, does not fall under the purview of the Medical Devices Rules, 2017.

Temple said that if it ever intends to introduce a feature for a medical purpose, it will seek CDSCO approval before making it available to users.

The Regulatory Road

Uncertainty extends beyond how companies position their products into what regulatory clearances are needed.

The second founder, who had earlier spoken about the importance of clinical trials and third-party validation, said their company obtained CDSCO approval despite not making any medical claims. The founder said the company pursued approval because it was developing a brain-focused wearable device.

"In India, any brain wearable device needs CDSCO approval. Whether it is tracking blood flow or not," the second founder claimed, adding that wearables targeting the brain face additional requirements compared with other wearable devices. "Even though I am not making a medical device, I have a CDSCO clearance. Because it is mandatory in India."

The approval process in this case stretched around 16 months from November 2024 to March 2026. We were told that before receiving approval, companies can test only a limited number of units in India, with CDSCO determining the permitted number. This also makes it harder for companies to continuously iterate and test.

The founder was describing their company's regulatory experience. However, CDSCO's 2026 guidance on medical device software does not establish a blanket approval requirement for all brain wearables.

The founder acknowledged that rules remain unclear for products positioned as wellness devices. They also pointed to gaps in enforcement, saying regulatory scrutiny is not always consistent. "The CDSCO is not very active in looking into such companies, unfortunately. This is a loophole in India that many exploit," the founder said.

A third founder said navigating regulatory requirements can be difficult for early stage startups, leading some companies to be over-cautious. "Here you need to play around with the regulatory parts. Because in India the regulations are very hard. The only reason we never say that it is a medical device is that compliance becomes very hard. Especially for a new startup."

The founder said companies need to be particularly careful about making claims related to detecting or predicting medical conditions. "So if we say we can detect, then it would be a medical device. So you have to play very carefully with the words."

The question, therefore, is whether wearable manufacturers are making claims that bring their products within the scope of medical-device regulation, regardless of how they choose to market them.

Beyond medical device approvals, the founder also highlighted other certifications such as Wireless Planning and Coordination (WPC) approval for relevant equipment that allows wireless connectivity, and Bureau of Indian Standards (BIS) certification that are mandatory for electronic devices.

Similarly, the US Federal Communications Commission (FCC) framework applies to relevant products marketed in the US and should not be confused with Indian regulatory clearance. Bluetooth Low Energy (BLE) certification, meanwhile, relates to an ultra-low-power short-range data transmission over Bluetooth.

The Temple spokesperson told Inc42 that it holds all the certifications required to sell the device in the countries where it is currently available. However, the company did not specify the individual certifications.

Does The Wearable Industry Trust Temple?

Temple's development also needs to be viewed in the context of Goyal's earlier work through Continue research and the Gravity Aging Hypothesis.

The hypothesis explores whether gravity's long term influence on blood circulation could contribute to aging, particularly through changes in cerebral blood flow. Goyal has previously argued that understanding brain circulation could help researchers investigate longevity and aging.

Temple emerged from this broader research effort. The device was developed to monitor brain-flow-related signals continuously, giving researchers a way to study physiological changes outside conventional laboratory settings.

However, a hypothesis, a measurable physiological signal and a validated biomarker are all different things. Establishing a relationship between a wearable's readings and an existing clinical measurement does not automatically demonstrate that the device can predict aging or provide meaningful insights into longevity.

One of the founders we spoke to said Temple's placement near the temporal artery was a considered engineering decision, as the location offers a relatively accessible site for optical sensing. However, the founder cautioned that measuring blood flow at the temple does not necessarily establish that a device can measure blood flow within the brain.

The second founder suggested the strength of Temple's existing athlete study as a basis for broader performance claims arguing that larger studies involving control groups and independent validation would provide greater confidence.

For Goyal, the next task is to establish that Temple's proprietary measurements offer meaningful information beyond existing wearable metrics.

In his November 8 post, he said consumers were free to wait for peer-reviewed evidence before purchasing the device. He also promised a detailed explanation of how BrainFlow is calculated, its potential application and its limitations.

The wearable industry does not necessarily need every product to become a medical device; some can remain lifestyle devices. But as manufacturers move beyond counting steps, measuring sleep and tracking heart rates to developing new physiological benchmarks, they will have to show what those numbers actually mean, and how they actually derived it.

Breakthrough products often begin with a hypothesis. Innovation lies in testing it, learning from the evidence and iterating, while being clear about the outcomes achieved and what remains under study.

Many senior founders and investors have shown faith in Goyal's ability to build Temple, pointing to his record of building and scaling Zomato and Blinkit (Eternal). Temple is an opportunity for him to bring that experience to a far less proven field: establishing a new category of wearable technology.

Most importantly, Goyal has shown conviction by committing substantial personal capital to Temple.

However, its scientific claims will need to withstand independent scrutiny before consumers can judge what the device can deliver.

If Temple can successfully demonstrate that, through continued testing and iteration, it could help create the wearable playbook India lacks.

Edited By Nikhil Subramaniam

Creatives: Abhyam Gusai