After 12 years of practicing family medicine in Wellesley, Massachusetts, Ronda Rockett was losing faith in her ability to help the majority of her patients.

Patient after patient would stream into her clinic with diabetes, weight problems, and heart disease. Rockett followed the medical guidelines, recommending healthier diets and more exercise. But despite her best efforts — even texting and emailing motivational follow-ups — many failed to change at all, either because they didn’t want to or didn’t have the means.

In 2013, eager to try something new, Rockett decided to quit medicine and close up her practice. What she did next, she says, is the most meaningful contribution to health care she’s made to date. She opened a CrossFit gym.

CrossFit is a high-intensity interval training and resistance exercise routine known for instilling a cult-like devotion among followers and promoting the low-carb diet. By the time Rockett opened a gym, she was already a devotee. Now age 51, she can do 32 pullups and deadlift 240 pounds. She attributes her fitness and lowered cholesterol to the program. And she believes she can help people make more substantive changes in their lives through CrossFit than she ever could practicing medicine.

“It’s exciting that I can treat and cure medical problems in the gym,” she said. “Just in the last week alone, I’ve gotten three different texts from people saying, ‘I don’t think you understand how much this has changed my life.’” Though she had 2,000 regular patients at her clinic and now works with just 70 regulars at her gym, she’s convinced she’s having more impact on each individual. Plus, she said, “This is more fulfilling.”

That CrossFit could be a substitute for, or an extension of, health care in America may seem like a stretch. But this is precisely the vision of CrossFit’s charismatic, contrarian, and often combative founder and CEO, Greg Glassman. These days, Glassman is on a quest to disrupt health care and solve the growing crisis of chronic disease related to diet and inactivity. And he wants to do this one CrossFitting doctor at a time.

A couple of years ago, Glassman discovered that at least 20,000 US doctors regularly went to CrossFit gyms. He also learned that many of them felt like Rockett — disappointed by their inability to prevent chronic disease and help patients change their behavior.

“Medicine is supposed to be about helping you through the accidents — the misfortune of a genetic disease, the misfortune of a trauma, the misfortune of some pathogen,” Glassman said. “Nobody went to medical school to babysit someone through a life of self-inflicted misery because of two deadly habits: sedentarism and excessive consumption of refined carbohydrates.”

CrossFit, meanwhile, is a radical intervention, the “elegant solution” to the chronic diseases of obesity and diabetes ailing so many people, he said.

 Courtesy of CrossFit Inc.

Since January, he’s hosted 340 doctors for weekends of networking, lectures, and a free two-day level-one CrossFit training course — the minimum requirement for anyone who wants to open a CrossFit gym. The next “MDL1” training will happen this weekend, at CrossFit’s headquarters in Scotts Valley, California. And Glassman has already expanded his offering beyond the US, to France and Brazil, in response to physician demand, he says.

The new endeavor — called “CrossFit Health” — is the future of his business, Glassman said. It might also be his legacy. By amassing and coaching an army of doctors, through CrossFit’s 15,000 affiliates around the world, he envisions nothing short of a global disruption of the health space. “[Doctors have] gone back [from the training weekends] a little bit militant. More eager to talk to one another and their colleagues; more likely to take a patient by the hand and bring her into the gym,” he said.

When asked what he hoped might come of the doctor trainings, Glassman was vague. “We thought it would just be nice to network [the doctors],” he said. When pressed, though, he articulated a big wish: While he wasn’t interested in drawing doctors away from medicine, he hoped they’d feel empowered to think about prescribing CrossFit to patients, incorporating it in their medical practices, maybe even opening up CrossFit affiliates.

In my years of medical reporting, I’ve come across hundreds of trainers, doctors, celebrities, and scientists who’ve promised permanent weight loss, longevity, and lasting health. As their fads have come and gone, the obesity and diabetes epidemics have only worsened, and, on average, Americans still aren’t exercising.

But Glassman’s view is distinct. Rather than focusing on patients’ frustrations with the limits of medicine — something celebrities Dr. Oz and Gwyneth Paltrow have exploited — he is now setting his sights on the dissatisfied deliverers of health care: the doctors.

Doctors, Glassman says, can see that CrossFit “fucking works.” And he’s become an unlikely advocate for solving an inconvenient problem: With the exception of bariatric surgery, doctors have few tools for treating, let alone preventing, obesity and other lifestyle-related diseases.

Glassman is working off a big and dubious assumption about the solution, however. He presumes obesity and diabetes are self-inflicted and that individuals can make changes — at a time when most researchers would argue these epidemics are driven not by a failure of willpower but rather by our calorie-drenched, obesogenic environment.

Helping people reap the benefits of any exercise also means getting them to do it regularly. And according to McMaster University kinesiology professor Stuart Phillips, nobody’s solved the exercise adherence problem. Not even Glassman.

So whether CrossFit-trained doctors really can be the revolution that vanquishes chronic disease is still very much up for debate.

What is CrossFit?

With the explosion of boutique gyms and ultramarathons over the past decade, it can feel like exercise is growing more expensive and more extreme. CrossFit has led the way.

The chain, with monthly membership fees of up to $250, has a reputation for delivering punishing exercises fit for Olympians to average folks who get injured easily. So when I went into my first CrossFit class in Toronto, I was thinking about the brand’s unofficial mascot, Uncle Rhabdo, named after rhabdomyolysis, a condition that’s brought on when you work out so hard, your muscle fibers break down and release into your bloodstream. I was also thinking about Glassman’s early maxim that CrossFit “can kill you.”

Instead, I found something much milder, much friendlier. The hour-long workout — a rapid-fire series of movements, drawn from weight-building, gymnastics, and calisthenics — definitely veered closer to an Army drill than a hatha yoga class. But the instructor scaled the routine for people (like me) who were weaker than average, and looked out for our form in every squat, row, and pullup.

There are no studies comparing the long-term health effects of CrossFit to other workouts, but there is a rich literature on high-intensity interval training (HIIT) — and it does pack in the benefits typically associated with longer exercise sessions. One is cardio-respiratory fitness. A number of meta-analyses have shown that HIIT routines lead to greater gains in VO2 max — the maximum amount of oxygen a person can use during intense exercise — compared with other forms of training. Short bursts of intensity may also reduce the risk of Type 2 diabetes by improving the body’s response to insulin and blood glucose.

A small study on CrossFit in people with Type 2 diabetes showed similar blood sugar improvements, and another suggested CrossFitters “spent significantly less time exercising per week, yet were able to maintain exercise enjoyment and were more likely to intend to continue” than people doing a more moderate workout.

CrossFit also comes with a heavy dose of resistance training — the lifting, pullups, and pushups that help build muscle. “Resistance training promotes greater strength. Aerobic exercise promotes greater aerobic fitness. You need both. And this is key: CrossFit provides both,” Phillips told me. “If CrossFit’s done anything, it’s introduced resistance exercise to a lot of people that never would have considered doing it.”

With all these benefits come risks. CrossFit can lead to injuries, most frequently in the shoulders, knees, and low back. But despite its reputation, the injury rate at CrossFit looks a lot like other similar workouts, such as powerlifting or gymnastics.

Part of CrossFit’s reputation for being dangerous seems to have been manufactured by a now-retracted study (more on that later). The other part seems to have been generated by Glassman himself, who used to talk about rhabdo as evidence for the workout’s “potency.” (When he said that, in 2005, there were already five cases of CrossFit-related rhabdo, all leading to hospitalization, and when asked today, the company said it didn’t have a more current figure.)

 Joanne Rathe/Boston Globe via Getty Images

In the class, my instructor was silent on diet, but CrossFit also has a reputation for zealously promoting the paleo and low-carb diets, with particular scorn for refined sugars and carbohydrates. That reputation was borne out in my conversations with CrossFitters, who claimed that cutting carbs could fix everything from plantar fasciitis to obesity.

They picked this up from instructors, who are trained to lecture on removing added sugar and reducing processed carbs, CrossFit’s director of government relations and research, Russ Greene, told me. This feature is what sets it apart from other workout programs that ignore diet, he added.

For me, what really set the class apart was the sense of community. Other members, recognizing I was new, repeatedly asked how they could help me and offered tips. Rather than isolating themselves with headphones like gym-goers normally do, my classmates were communicative, talking, joking, and encouraging one another throughout the workout.

There were no mirrors in sight. This matched what scholars who have studied CrossFit have concluded: It is akin to a religion. CrossFit “boxes,” as the gyms are known, are spaces where like-minded people can gather and experience a sense of togetherness.

At the end, I felt strong and uplifted. It wasn’t hard to see why CrossFit has spread so quickly, and why so many people are hooked.

Glassman’s “holy war” with big soda

Glassman, a college dropout who got his start training people in LA’s gyms — and getting kicked out of several of them — opened his first CrossFit box in 2001. Since then, the chain has mushroomed into 15,000 affiliates in more than 160 countries. CrossFit Inc. reportedly generates about $100  million in annual revenue, and Glassman’s net worth is said to bejust as large.

Through CrossFit’s websites, podcasts, videos, and the brand’s CrossFit Journal, Glassman has managed to infuse the brand with his anti-establishment, libertarian viewpoint.

It’s not uncommon to find scathing critiques of the Agriculture Department’s ”food pyramid” in CrossFit’s online communities, or debates about whether being a CrossFitter makes you a libertarian.

“Strong conviction to the tenets of individualism and responsibility make CrossFit look less like a fitness program and more like a course in Libertarianism,” wrote CrossFit’s social media director Russell Berger in 2008.

 Linda Davidson/The Washington Post via Getty Images

Glassman holds the view that high cholesterol and a diet rich in animal fat don’t cause heart disease — and promotes controversial scientists who believe the same. When pressed on these beliefs, he railed against “consensus science.”

His personal philosophy is also reflected in the brand’s business model. CrossFit is structured around a loosely affiliated network of gyms, or boxes. Anyone who wants to open a box simply has to attend a two-day level-one training course and pay a $3,000 yearly fee, among other minimal barriers to entry. Each box is independently owned and operated, with little interference from headquarters. CrossFit makes its money by accrediting trainers and licensing its name to owners.

Altogether, Glassman’s worldview and business model have proved a major success, as he reminded me a few minutes into our first conversation. He pointed out that he’s regularly invited to lecture at Harvard Business School because CrossFit is now “the fastest-growing chain in world history.”

“I was 45 and broke. I’m 62 and filthy rich,” he said. “I have four or five homes. What does a guy need? It’s getting stupid. I’m set. I’m motivated clearly by something else.”

That “something else” is bettering public health, he says. Specifically, Glassman is engaged in what he calls a “holy war” with big soda, which he blames for causing obesity and diabetes and interfering with public health efforts. Through lectures to doctors, conferences, meetings with members of Congress, YouTube videos, and Freedom of Information Act requests, he’s trying to draw attention to what he sees as their perverting influence on public health.

The focus stems, in part, from a lawsuit CrossFit filed against the National Strength and Conditioning Association (NSCA), a group that certifies fitness trainers and is a competitor of CrossFit. The group published a study showing CrossFit is dangerous, as the Washington Post reported, and Glassman discovered the NSCA is partially funded by Pepsi. (The NSCA study included false data, and the journal wound up retracting the study in 2017 because of ethical breaches.)

The more Glassman explored the nature of the soda industry’s influence on health, the more he and his team started seeing and publicizing big soda’s fingerprints everywhere — funding studies, sporting events, even donating money to the foundations of government institutions like the National Institutes of Health and the Centers for Disease Control and Prevention. CrossFit, for instance, was the first to discover that Trump-appointed ex-CDC Director Brenda Fitzgerald had ties to Coca-Cola.

If Glassman could, he would “[drive] soda out of the health space,” he says. To that end, CrossFit has supported soda warning labels (though Glassman stops short of supporting a tax). CrossFit recently sued the federal Health and Human Services Department to force the foundations behind the NIH and CDC to make public the list of donors who support them, as well as the amounts and restrictions that come with the donor money. The lawsuit was inspired by learning that these foundations have accepted money from the pharmaceutical and food and beverage industries.

The food and beverage industry’s “corruption” of public health is what has made us fatter and sicker, Glassman said, and “it’s making the medical space a horrible space to be.”

 Andrew Errington/Getty Images

What’s the antidote? Naturally, Glassman believes, it’s CrossFit. “If you do not restrict your consumption of unnatural carbohydrates, and if you don’t take all of your joints through a full range of functional movement that gets you breathing hard and sweaty on the regular, you’re not going to have a normal life,” he said.

(There’s a lively scientific debate about the relative benefits of the low-carb diet, the extent to which it’s helpful for weight loss, and whether it’s better than any other diet.)

He continued: “Every day, a new person comes into the gym and gets the right answer in a distributed model that’s working like few things have worked in modern business times.”

“The majority of physicians are becoming very desperate”

The medical profession was organized more than a century ago at a time when acute illnesses — pneumonia, tuberculosis, scarlet fever — were the major health threat. As medicine and our understanding of the germ theory of disease have progressed, deaths from infections have fallen away, and the overwhelming burden of illnesses that doctors in developed countries now face is chronic in nature — heart disease, cancer, diabetes, Alzheimer’s.

Doctors are not always equipped to deal with this new reality, which is why many people before Glassman have thought about how to better incorporate measures like exercise or dietary advice into health care.

Yet over the past several decades, the standard prescription on offer in America for patients with diabetes and obesity has simply been to tell them to clean up their diet and exercise more. And that hasn’t worked. The CrossFit-supporting doctors I spoke with for this story, who attended the weekend training courses, acknowledged that fact. They seemed to have something more radical in mind.

They spoke of taking patients to the gym with them, or opening CrossFit boxes right in their hospitals. Like Ronda Rockett, they all expressed frustration with their inability to prevent and treat chronic disease in their practices.

“The majority of physicians are becoming very desperate,” said Nathan Riley, an OB-GYN at Scripps Memorial in Encinitas, California. “We are finding the Western medical model isn’t providing us with the tools to help people. Most physicians don’t see we’re doing anything to improve people’s health.”

At a CrossFit training course for doctors, which he attended in February, Riley had the space to think “maybe the medical system isn’t the way to go. Maybe I need to change things up.”

Lauren Vigna, a Highland, New York-based doctor who has been doing CrossFit for a decade, echoed Riley’s frustrations — and the opportunity CrossFit holds. “People who do CrossFit know that you can do a lot without any medicines; you just need to focus,” she said. “High cholesterol, high blood pressure — CrossFit can fix all those things through diet and exercise.” Going to the training course left her with a feeling of “indebtedness” to Glassman and thinking about how she might have patients join her in CrossFit.

“For me,” she said, “the best combination of this would be to have an office, see patients, and have them all meet me for a workout at 5.”

While CrossFit may be a solution, it’s probably not thesolution

Other exercise scientists and obesity doctors I spoke to were much more skeptical of Glassman’s vision.

“We have a lot of [health problems] that could be addressed by better lifestyle, but the question is ‘how generalizable is [CrossFit].’ In my opinion — having taken care of thousands of patients — it’s not generalizable,” said Dr. Michael Jensen, an obesity and metabolism expert at the Mayo Clinic.

“[The people] who are in most need of correcting metabolic disorders — overweight, out of shape, busy, stressed — are very unlikely to be able to do what CrossFit wants them to do, physically, emotionally, lifestyle-wise.”

Jensen was getting at the question of whether CrossFit can truly help those most in need: the non-exercisers. “The biggest reduction in risk for every single known chronic disease when it comes to physical activity happens when you get somebody who does nothing to do something, and I mean anything — going for a walk,” said McMaster University’s Phillips.

There’s no substantive evidence — at least not yet — that CrossFit can transform these folks over the long term, he added, even with doctors prescribing the program.

“Exercise is truly a wondrous thing for health,” said obesity physician Yoni Freedhoff. “But suggesting there’s something unique to CrossFit probably isn’t evidence-based. And then there’s the fact that the percentage of the population sufficiently privileged to intentionally find consistent, multiple times per week exercise blocks is very, very small.”

In response to this critique, Russ Greene, the CrossFit executive, said the company has always delivered workouts for free on its website.

 Ron Jenkins/Fort Worth Star-Telegram/MCT via Getty Images

There are other reasons it’s hard to imagine CrossFit as an end-all solution to chronic diseases like obesity. Researchers no longer think of obesity as a personal failing. They believe some people have genetic and hormonal traits that make them more susceptible to the condition, and view it as a complex, chronic disease, like cancer, with many causes and subtypes.

Among the non-genetic factors that most contribute to the condition are childhood abuse, depression, and low maternal education. That’s why they’ve been losing faith in dieting and exercise to treat the condition, neither of which is very helpful for weight loss in the long term.

At the same time, there’s a growing awareness that our environments shape our health. More people are now experiencing weight problems and even diabetes at least in part because we are surrounded by calorie-rich, nutrient-poor food choices, and our neighborhoods often don’t promote exercise.

This is especially true for the neediest among us. According to the American Time Use Survey from 2015, the poorest quartile of the population gets about half the exercise of the wealthiest quartile. What’s more, people of color are also disproportionately affected by obesity and diabetes, and CrossFit has had a reputation of being unwelcoming to these communities.

Changing these systemic factors would, many argue, turn the obesity epidemic around. CrossFit, a private company with a steep membership fee, probably can’t do that.

When I talked to Rockett about this conundrum, she acknowledged that many of her former patients were sick because of their social circumstances.

“I had some [patients] on really limited budgets — and it was very frustrating. They did not always have access to fresh food,” she said.

She still viewed CrossFit as a potential fix, maybe not for everybody, but for some. “We have many members who have lost 10, 20 pounds. One woman had arthritis, and we put her on a [low-carb] diet and her symptoms went away.” Plus: “With my members, I spend five hours per week. As a doctor, I spent 10 minutes with [patients].”

As a society, we’ve structured health care (and reimbursed providers) to address existing health woes, not to prevent them. If we focused on making exercise and healthy eating easier for more people, we’d unquestionably be better off.

But that diet isn’t necessarily low-carb or paleo, and the right exercise doesn’t have to be CrossFit. Simply opening more CrossFit boxes, or getting doctors involved, may help — but it likely isn’t going to fix this broken system.

As kinesiology professor Phillips said, “I’ve yet to see the magic in CrossFit that makes it the, as opposed to an exercise-based solution for population health.”