The New Breathalyzer for Keto Dieters

Keyto says it analyzes your breath to tell you how much fat you’re burning. But does it actually work?

Image: Keyto

AtAt a glance, the palm-sized breathalyzer could easily be mistaken for a vaping pen. But Keyto, a handheld breath sensor with an accompanying mobile app that announced its retail launch earlier this month, isn’t designed for partiers. Instead, it’s a diet-tracking device for disciples of keto, a restrictive low-carb, high-fat diet that drives the dieter’s body into a metabolic state of ketosis, during which the body burns fat for fuel rather than carbohydrates.

Keyto co-founder and CEO Dr. Ray Wu, a former vice president of product management at Weight Watchers, also claims that it’s the most accurate device of its kind on the market.

“It’s a really great mechanism for getting feedback on your food choices,” says Wu. “You breathe into the device and the app will tell you your keto level in real time, seconds later.”

The company, which sells its breath sensors for $99, raised more than $1 million and pre-sold 12,000 devices during the Indiegogo campaign it launched in December. Keyto is part of a wave of so-called digital wellness services that have proliferated in recent years, including meditation, ancestry, and fertility apps.

And no one is regulating them. Of course, that’s no accident.

“Active FDA oversight would provide little to no public health value while unnecessarily delaying patient access to potentially beneficial technologies,” Dr. Scott Gottlieb, then-head of the Food and Drug Administration, wrote in an op-ed on medical app regulation that he co-authored in JAMA last year. In other words, Gottlieb believes regulation would slow down and hinder innovation.

In 2016, the FDA codified its hands-off framework in a guidance it issued on mobile health, which was part of the 21st Century Cures Act, a law intended to speed up the development of innovative medical products.

An FDA official reached by OneZero explained that, similar to medical devices, if an app carries a low risk to patients — the digital equivalent of a toothbrush or a Q-tip — the FDA doesn’t get involved. Higher-risk apps — the digital equivalent of a pacemaker — require more oversight.

The impetus is on the company to determine whether their product is of low risk or high risk to consumers, but the FDA offers informal and formal opportunities for companies to get guidance about which bucket they fall into, the official said.

“We talked to expert FDA consultants, at length, who advised that Keyto fits squarely under the FDA General Wellness Policy,” Wu says.

Miscategorizing a high-risk device as low-risk could eventually subject a company to fines, recalls, or other punitive action from the FDA. Still, the agency’s standards mean that wellness products like Keyto remain unregulated in a literal sense, putting a higher burden on consumers to gauge whether they’re safe and effective.

“It’s hard to know whether an app is good or bad, unless it makes headlines.”

“There’s no way to regulate or evaluate these apps, other than the user ratings,” says Jody Lyneé Madeira, a professor who teaches torts, law and medicine, and product liability at the Maurer School of Law at Indiana University in Bloomington.

“It’s hard to know whether an app is good or bad, unless it makes headlines,” adds Scott Thiel, director of life sciences at the consulting firm Navigant. At a glance, Thiel says Keyto appears to be ticking all the classic boxes for a wellness app, because it isn’t making any medical claims. As with low-risk medical devices, which are similarly unregulated, the risk of being hurt by a wellness app is slight.

“You don’t hear much about toothbrush and sunglass companies coming under fire by the FDA,” Thiel says.

So, Keyto won’t hurt you. But will it do what it promises?

Wu claims that it’s the most accurate keto breath sensor on the market, and he may be right. Blood and urine keto tests have been available to consumers for years, and studies, including those conducted long before Keyto was conceived, indicate that breath acetone, which the Keyto device measures, can be a reliable indicator of ketosis.

“In the development stage, we did thousands and thousands of tests and compared Keyto to blood- and pee-based tests,” Wu explains.

Some companies may choose to forgo rigorous studies up front until they’re more established. Thiel says he has clients who develop products and bring them to market under the wellness umbrella to generate cash flow and collect real world evidence. Later, they conduct studies and earn medical device clearance — which was really their plan all along.

Breath acetone, which the Keyto device measures, actually can be a reliable indicator of ketosis.

Still, “the accuracy side is like the black hole,” counters Arthur Caplan, the founding director of New York University’s Division of Medical Ethics. “They can claim anything they want, but I would like to see some studies or laboratory results from independent labs.”

“The nature of scientific, peer-reviewed studies is that they take awhile,” Wu says. “We have them in the works.”

But as we know from Elizabeth Holmes’ Theranos debacle, trusting a team of doctors, engineers, and scientists to conduct internal research and development isn’t a substitute for peer-reviewed studies or clinical trials. Independent scientific evaluation has the added benefit of oversight and transparency, and allows for outside experts to critique the science behind why devices and apps work.

When Keyto users blow into the breath sensor, the app spits out their keto level, a number between 1 to 8. “We tell users that at level 5 and above, you are in a state of ketosis,” Wu says. “At these levels, you can expect to see results.”

Similar to other wellness apps, such as the Apple Watch’s activity competitions, Keyto is set up like a game. “People love talking about their Keyto levels,” Wu says. Indeed, a video on Keyto’s Indiegogo page depicts pairs of friends using their breathalyzers while cooking together and checking their Keyto mobile apps while ordering food at a restaurant.

While the app may not explicitly encourage users to achieve keto level 8, Madeira worries that consumers might make reaching the top keto level their diet goal. “There might be some people who stay healthiest when they just reach ketosis, at 5,” she explains, noting that athletes, who don’t have much fat to begin with, harness energy from carbohydrates more efficiently than they do from fat.

Madeira suggested that Keyto could avoid liability problems by having an expert design a scientifically validated test to determine whether the keto diet is right for potential users. That test could weed out athletes or people with disordered eating patterns, and guide users as to “whether they should blow an 8 or whether they should be content with a 5,” Madeira says.

Wu says it’s an idea he’d be willing to consider in the future.

But despite the proliferation of wellness devices and apps like Keyto, Caplan doesn’t think that nutritionists or doctors are likely to begin recommending them to patients anytime soon.

“In terms of technology, I think a scale is your number-one purchase,” he says.

Public health reporter

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