IOWA CITY, Iowa — Terry Wahls can walk. She can ride her bike. She can run two miles on a treadmill. She can tend to her backyard garden, which on an unseasonably warm April afternoon in Iowa City, is in the chaotic throes of the early Spring growing season.
Wahls gives a tour, her 14-year-old dog, Teddy, trailing: Persimmon and pawpaw trees, thornless blackberries and raspberries her grandchild will pick when they ripen. The peas have sprouted.
A wheelbarrow her father built decades ago rests near the garden’s edge, returned years later by a stranger who recognized it during her son’s state senate campaign.
The back room of her house is mid-renovation; she removed an exercise pool her mom persuaded her to install two decades ago when Wahls faced a downhill spiral from multiple sclerosis and could no longer bike or swim or ski. Back then, she was a physician facing an early end to her medical career, and the possibility that, in her 50s, she might spend the rest of her life in a nursing home.
Today, she no longer needs the pool.
Terry Wahls sits in her backyard in Iowa City, Iowa. Credit: Jess Craig/Straight Arrow
Wahls says she reversed her disability through a regimen of diet and lifestyle changes, turning away from the conventional treatments she had been trained to practice. Her account has drawn both devoted followers and sharp criticism. Some dismiss it outright; others question the science behind it. But her story has helped fuel an increasingly influential alternative approach to treating disease.
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‘Food is medicine’
Today, Wahls is one of the most visible figures in the growing functional medicine movement, which emphasizes the role of diet, lifestyle and underlying biological systems in chronic disease.
San Diego nutritionist Norma Flood likens the body to a tree. The roots are the inputs — diet, sleep, stress, even constant exposure to electronic devices. They feed the trunk, which represents a person’s underlying biology: genetics, stage of life and the state of the microbiome, the bacteria and other microorganisms in the gut or on the skin.
“Each person’s trunk is completely unique,” Flood said. “That’s why some people can handle certain inputs better than others. Like, how come that person gets away with eating all that crap food, and I eat it, and I don’t handle it well?”
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The leaves are the outward symptoms that result from the interaction of those roots and trunk: acne, allergies, even autoimmune diseases like MS.
While conventional medicine focuses on treating a person’s leaves, functional medicine takes aim at the roots.
The movement isn’t new, though it has recently moved from the fringes into a spotlight that grows ever brighter in the second Trump administration. One-time surgeon general nominee Casey Means is a well-known functional medicine practitioner, and both Health Secretary Robert F Kennedy Jr. and recently resigned Food and Drug Commissioner Marty Makary have advanced a “root cause” framing of chronic diseases. This April, hundreds of insurers, including Aetna, Cigna and UnitedHealthCare, added the functional medicine telehealth company Parsley Health as an in-network provider.
US physician and wellness influencer Casey Means, nominee for US Surgeon General, testifies during a Senate Health, Education, Labor and Pensions (HELP) Committee confirmation hearing on Capitol Hill in Washington, DC, on February 25, 2026. Credit: Brendan SMIALOWSKI / AFP via Getty Images.
As the number of Americans living with chronic disease has grown to about 60%, according to the Centers for Disease Control and Prevention, functional medicine advocates argue their approach offers a potential solution.
Not everyone agrees.
A booming commercial ecosystem — worth an estimated $66 billion — has emerged around functional and other types of alternative medicine. There are numerous direct-to-consumer companies offering microbiome and genetic tests that can be expensive and, in some cases, not yet supported by strong clinical evidence or covered by insurance. Instead, many practitioners operate cash-based practices, though some conventional physicians incorporate elements of functional medicine into traditional care.
Critics say the combination of limited evidence and high out-of-pocket costs can make the field appear driven as much by revenue as by patient benefit. Many functional medicine practitioners, including Wahls, sell supplements on their websites, blurring the line between care and commerce.
“I can spend thousands of your dollars to investigate and understand all these biochemical pathways and design a very comprehensive approach to address all these things,” Wahls said. “It’s a terrific way to make a lot of money.”
But at its core, functional medicine is not about expensive testing or supplements. The foundation is far more basic: eating whole foods, exercising, sleeping well and otherwise maintaining social and emotional well-being. Those interventions are largely in the hands of individuals, not for any single industry to monetize.
Conventional medicine is also deeply shaped by powerful commercial interests. The country’s health insurance industry is worth more than $1.5 trillion, the pharmaceutical industry more than $600 billion. Health insurance and pharmaceutical CEOs earn salaries upwards of $26 million.
Functional medicine hasn’t made Wahls rich, she said. She still lives in the same modest, Midwestern ranch house she moved into in 2000. She drives a RAV4.
First signs
In the 1980s, when Wahls was in medical school, she had sudden jolts of pain at her temple. At first they were mild. Over time, they intensified — sharp, electric bursts that spread along her jaw. Sometimes her vision momentarily blotted out. Her knees buckled. The muscles in her legs weakened. An involuntary grunt escaped her lips.
The medical term for the pain is trigeminal neuralgia, but Wahls called them “zingers.” The episodes became more frequent and more severe. Sometimes they lasted a week. Wahls went to a pain clinic, where doctors prescribed gabapentin. She moved from taking the drug during flares to daily maximum doses.
For a stretch, the zingers were her only complaint. Wahls went on with her life. She graduated from medical school in 1982, moved to Missouri for an obstetrics residency, then settled in Wisconsin to focus on internal medicine. In 1991, she gave birth to her son Zach, followed by her daughter Zebby. In 1994, she met her wife, Jackie Zeger, at a lesbian potluck.
Terry Wahls (left) and her wife, Jackie Zeger (right), pictured in 1995 with their two children, Zach and Zebby. Image courtesy of Terry Wahls.
Six years later, Zeger — then a nurse practitioner in urgent care — noticed a subtle weakness in Wahls’ left leg. Wahls brushed it off. To prove her point, Zeger made her walk three miles — enough for Wahls to realize her wife was right. In the coming months, she underwent an MRI, bloodwork and a spinal tap.
Wahls remembers her diagnosis vividly. She signed into her online patient portal, where her spinal tap results showed elevated levels of antibodies, indicating inflammation.
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She logged on again. Once, twice, five times. Finally, she realized: “The results are not going to change.”
Wahls was familiar with MS. She knew it often progressed steadily, and that within three years of diagnosis, more than 40% of patients were unemployed.
“We’ll go find the best MS center; let them take care of you,” Zeger told Wahls.
So they went to the Cleveland Clinic.
A new way of thinking about disease
As Wahls wrestled with her diagnosis, the functional medicine movement was taking shape a few states over, in Washington.
In the 1990s, biochemist Jeffrey Bland reframed how the nation’s growing chronic illness was understood and treated. Where conventional medicine might prescribe a drug to lower blood pressure or manage diabetes, Bland focused on the “root cause,” taking aim at factors like diet or stress.
By the late 1990s, functional medicine coalesced into a more formal movement. Bland, his wife and another physician, David Jones, founded the Institute for Functional Medicine, which later became accredited to provide continuing medical education.
The ideas spread through a network of high-profile physicians. That included Mark Hyman, a long-time friend of Kennedy and a prominent functional medicine advocate who advised the Clintons on their diets after Bill Clinton’s quadruple bypass surgery. Hyman went on to publish several books on the health effects of sugar and even appeared on “The Dr. Oz Show,” hosted by the current head of the Centers for Medicare & Medicaid Services.
Physician and author Dr. Mark Hyman speaks during a news conference at the Health and Human Services Department on April 22, 2025 in Washington, DC. Credit: Andrew Harnik/Getty Images.
At the time, Wahls was still years away from encountering these ideas. But the questions driving the movement soon became her own.
Losing ground
When Wahls first arrived at the Cleveland Clinic in 2000, her doctors started her on a typical course of treatment: Copaxone; then a steroid when her right hand and arm became weak; then, over the next five years, more aggressive therapies, including a chemotherapy drug and an immune-suppressing medication that left Wahls with painful mouth ulcers and grayish skin.
Despite the medications, Wahls’ friends watched as she slowly slipped toward increased disability.
Terry Wahls pictured with Cub Scouts in 1996. Image courtesy of Terry Wahls.
Carolyn Johnson, Larry and Sarah Jewell met Wahls through the local Unitarian Universalist Church, where their sons were friends. Throughout the early 2000s, the group spent the second week of every July camping together in Lake Geneva, Wisconsin.
Each year, Wahls needed a bit more support. One year, she came to camp with an ankle brace because her foot was dropping. The next year, she had a cane. The next, a wheelchair, Johnson said, “just in case.”
It felt sudden when Wahls started using a tilt-recline wheelchair.
“She was fighting it all the way,” said Sarah Jewell. She still remembers the first time Wahls arrived in the wheelchair for Thanksgiving dinner at her home. When the children were out of earshot, Wahls spoke about how difficult it was to face an uncertain future with them.
“It was tragic to watch,” Jewell said.
But Wahls’ children inspired her to keep going, even as she felt conventional medicine failed her. She scoured basic science studies — experiments in animals or cells in a lab — for ideas. During visits with Johnson and the Jewells, Wahls shared what she learned about mitochondria — the cells’ energy generators — and how, when damaged or deprived of key nutrients, they became less efficient, driving one of the MS’s most common, debilitating symptoms: fatigue.
“She was not content to just accept that this was how her life was going to be,” Johnson said.
‘Scarring in patches’
Today, scientists have a clearer understanding of MS. According to Robert Bermel, a neurologist at the Cleveland Clinic’s Mellen Center for Multiple Sclerosis, there is “overwhelming evidence that MS is an immune-mediated disease,” meaning the body’s immune system attacks the brain, spinal cord and other parts of the central nervous system leaving behind scarring, called lesions. Those attacks cause blurred or painful vision, numbness or weakness in arms or legs and sometimes bowel or bladder problems.
Yet despite decades of research, much about the disease remains elusive.
“Why MS starts in any given person at any given time, has been difficult to answer at a population level and at an individual patient level. Patients will ask, ‘Why did I get MS?’ and the answer is generally complicated,” Bermel said. “It’s likely a combination of genetics and environment.”
It’s even possible the combination is different for every person. And the disease itself can present differently from patient to patient.
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Historically, untreated patients relapsed every year or so for the first eight to 10 years, followed by a gradual accumulation of permanent neurological problems. Older data suggested about half of patients would need a cane within 15 years, but that’s changing.
Today, earlier diagnosis and more effective drugs — most of which target the immune system — help physicians freeze the disease in place, preventing relapses, new lesions and the accumulation of disability altogether.
Wahls, and the wider functional medicine movement, does not outright reject the modern approach to treating MS. But as Wahls continued to decline despite all the offerings of conventional medicine, she wondered if something more was at play. She questioned not just what was attacking her body, but what might be failing within it, and whether the underlying health of her cells — how they produced energy and responded to stress — could be repaired.
An experiment on herself
By the summer of 2007, Wahls used her wheelchair around the clock. She could no longer sit upright on her own. Even with two walking sticks for support, she could manage only a few steps. Her facial nerve pain was frequent and severe.
Terry Wahls pictured in her wheelchair at work in 2006. Image courtesy of Terry Wahls.
“I’m clearly getting close to being bedridden,” she thought.
She drafted a will, instructing her wife and physicians not to intervene if she stopped eating.
As she neared rock bottom, her boss at the VA told her, come January 2008, she would see patients and manage a team in the traumatic brain injury clinic. Looking back, Wahls now believes her boss was pushing her to come to terms with her condition and retire from medicine.
She didn’t.
That September, as Wahls sat in her office, she picked up a proposal for a clinical study to test whether electrical stimulation of muscles in people who were paralyzed could help maintain muscle strength and bone density.
The idea caught her attention. Maybe it could help her.
Zeger tried to dissuade her, but Wahls’ physical therapist agreed to give it a try.
He placed electrodes on her skin and turned on an e-stim machine, a device that sends small electrical pulses through the skin to activate nerves, triggering the muscles to contract, mimicking normal brain signals. As he increased the current, Wahls’ muscles twitched beneath the pads.
The first session was brief, but Wahls felt slightly better afterward. So she bought her own e-stim machine. Soon, she wore the electrodes under her work clothes, shifting the pads to different muscles. She used the device every possible minute, reducing the current just enough so her muscles didn’t contract wildly in front of patients or colleagues.
Then Wahls went one step further.
When her neurologist suggested she look into the work of Ashton Embry, a geologist who had written about improving his son’s MS symptoms through diet, in 2002, she thought it sounded like fringe medicine. But with conventional medicine failing her, Wahls reconsidered diet. She discovered the Institute for Functional Medicine and designed a paleo-like diet that mimicked the regimen of supplements she was taking.
The day after Christmas 2007, Wahls committed to the new diet, which focused on whole foods — meat, vegetables, fruits and nuts — while avoiding modern ultraprocessed foods and grains.
Diet for MS
Long before Wahls experimented with diet, physicians had explored whether nutrition could influence the course of MS. In the 1950s, neurologist Roy Swank proposed a low-fat diet after observing that MS appeared less common in regions with lower saturated fat intake. He followed a group of patients over several decades, reporting those who adhered closely to the diet experienced fewer relapses and less disability progression.
Swank’s work remains influential, but much of it was observational and lacked the rigorous clinical trials needed to differentiate correlation from causation.
More recently, researchers have examined broader dietary patterns, including the Mediterranean diet, which has been linked with lower levels of inflammation and better overall health. Some research suggests it may be associated with improved quality of life and reduced fatigue in people with MS.
“The Mediterranean diet is probably the one with the best evidence in MS — along with higher-fiber diets — even though that evidence is still incomplete and we’re lacking more definitive data,” said Bermel.
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Diet, exercise and reducing risk factors like smoking or type 2 diabetes are “fine-tuning adjustments,” according to Bermel. Used alongside highly effective medications, he said the adjustments can suppress new lesions and relapses in more than 90% of cases.
Still, the extent to which diet alone can alter the course of MS remains hotly contested.
The bike ride
On Jan. 2, 2008, one week after starting her new paleo diet, Wahls began her new job. For the first two weeks, Wahls watched her colleagues from her wheelchair. On the Monday of her third week, after a full day of seeing patients, she tried sitting in a regular chair for a bit.
“First time I’ve done that in years,” Wahls said.
The next Monday, Wahls’ physical therapist noted her strength had improved; he gave her slightly more advanced exercises.
By the beginning of March, Wahls walked the hospital halls, stunning colleagues.
At first, Wahls wasn’t sure what to make of her sudden improvement. It felt almost impossible to believe. But she knew MS patients can experience temporary recoveries before relapsing.
By April, Wahls and Zeger were walking around the block.
On Mother’s Day, roughly five months after starting her paleo diet and eight months after beginning e-stim, Wahls decided she was ready to ride her bike.
“I don’t know what the hell I was thinking,” Wahls said.
She found her bike in the garage. When her children heard her working to lower the seat from the height her son had set it to, they took the bike away and called Zeger in.
“Mom’s out of control,” they said.
But Wahls was adamant, so the family formulated a plan: Zach and Zebby would run alongside Wahls on either side as Zeger trailed.
Everyone assumed their positions.
Wahls began to pedal.
After about half an hour, she made it around the block and back home, where the whole family erupted into tears.
“Up until then, I really did not have expectations,” Wahls said. “I was still thinking recovery is not possible. I didn’t know what any of this meant, and so I just took each day as it unfolded, and then after that bike ride, I knew what it meant.”
But convincing others that diet and lifestyle could play such a role in her chronic diseases remained an uphill battle.
Banned
That October, Wahls biked 18.5 miles in a local Courage Ride event, stopping for breaks along the way.
The ride changed the way she treated patients at the VA. In cases where some doctors thought there was nothing to be done, she saw hope.
“There’s a lot we can do,” she told patients. “We can help you work on your diet. Let’s do Epsom salt meditations. Get a step counter.”
Not everyone welcomed the shift.
“Part of the institution was just so thrilled to see me walking around doing so well,” she said. “They were thrilled about that, but they didn’t quite know what to do with the fact that I was now prescribing broccoli instead of drugs.”
Several patients lodged complaints with the hospital.
Wahls’ supervisor told her she needed to “learn how to play better in the sandbox.” He worried the complaints could trigger a Board of Medicine investigation, risking her medical license. So he sent Wahls to the university’s complementary medicine clinic to learn how to document her recommendations and better present her approach.
Terry Wahls delivers her TED Talk in 2011. Credit: Jbeyer Photography 2010
In November 2011, Wahls delivered a TED Talk about her recovery, focusing on the role of nutrition in supporting mitochondrial function. Within months, the talk garnered more than 1 million views.
The attention brought scrutiny. The National MS Society barred Wahls from speaking at its events, calling her ideas “dangerous.” Some neurologists accused her of offering false hope. Wahls maintained her paleo-based diet and continued to fold functional medicine into her clinical practice. Her supervisor encouraged her to share her ideas with those who were open to them.
In 2014, Wahls published her first book, which became a bestseller. The same year, the University of Iowa received one of several large donations — $300,000, according to Wahls — to support her research.
By then, the National MS Society was shifting its stance and invited Wahls to speak at a wellness conference. Two years later, the organization awarded Wahls a $1 million grant to study her paleo-based diet alongside the Swank diet.
She was gaining steam, but skepticism remained.
Body of evidence
Wahls refined her approach. Over time, she developed the “Wahls Protocol,” a progressively restrictive, three-tiered dietary plan that moves from a gluten-free and dairy-free diet to a strict ketogenic-style paleo diet.
Wahls also recommended supplements, electrical muscle stimulation, exercise, meditation and massage.
In 2014 and 2015, Wahls and her University of Iowa team published two year-long studies of the protocol. The first included eight people with MS, the second enrolled 20. Both reported significant reductions in fatigue, with one study showing average rates of fatigue dropping from 5.7 to 3.3 on a 7-point scale.
Both studies were small and lacked control groups, making it difficult to discern what caused the improvements. But they offered early evidence that diet and lifestyle might reduce fatigue for MS patients.
The studies kept coming. A 2017 randomized controlled trial found that subjects who followed the diet showed clear improvements in fatigue, hand dexterity and some quality-of-life measures.
In a later randomized trial of 77 MS patients assigned to follow either the Wahls or Swank diets, both groups reported significant improvements in fatigue, cognitive and physical function, along with weight loss and lower BMI. The Wahls group showed somewhat greater reductions in fatigue.
Most studies to date have been small and short-term. Funding is a barrier; rigorous trials cost millions. Wahls said she and her team are now completing a two-year study she hopes will provide clearer insight into the longer-term effects of a paleo-style diet in MS.
None of her studies have documented recoveries as dramatic as her own. Yet on Wahls’ TED Talk and other public forums, comment sections are flooded with people who say the protocol provided significant, life-changing improvements.
False hope or revolution?
Functional medicine is often criticized for adopting treatments based on a patchwork of evidence — including basic science, animal studies and limited clinical data — rather than waiting for the large, controlled trials typically required in conventional medicine
That dynamic is especially visible in some of the field’s core ideas. Identifying “root causes” often involves searching for underlying imbalances — such as disruptions in hormones, nutrient levels or the gut microbiome — that practitioners believe may contribute to inflammation, cellular dysfunction and, in some, chronic or autoimmune disease.
The Wahls Protocol is designed around these ideas. Its emphasis on nutrient-dense foods is intended to support cellular function, particularly in energy-producing structures like mitochondria, and influence the gut microbiome.
Many practitioners use extensive panels of biomarkers or microbiome tests to guide treatment and offer personalized recommendations. But while these areas are active and promising fields of research, scientists say the evidence linking specific test results to treatment pathways remains limited.
Functional medicine often takes “things that actually do have some relevance to disease and kind of run off a cliff with them, far beyond what the evidence will support,” said David Gorski, a surgeon and medical director at Karmanos Cancer Institute in Detroit and a professor at Wayne State University.
In his view, the underlying ideas are not wrong; they’re often applied in ways that are not rigorously validated.
The microbiome question
Microbiome testing has become a centerpiece of many functional medicine approaches, with patients receiving detailed analyses of gut bacteria and tailored recommendations to “restore balance.”
Extensive research consistently shows that people with conditions like MS and depression have different gut microbiome composition than others. But many physicians say we still don’t know what a “healthy” microbiome looks like. Nor do we know how or whether it can be reliably changed in ways that improve outcomes.
Animal studies suggest the microbiome can influence disease, but evidence in humans is mixed: A trial for Parkinson’s disease reported that microbiota transplants had no marked benefit, while another study for fibromyalgia reported significant improvements.
Some clinicians navigate that uncertainty pragmatically.
“I have many patients who try things like prebiotics and probiotics, and like to experiment with these things,” Bermel said. “Unfortunately, I don’t have a lot of definitive guidance that I can give them around this, but I would say the general guidance is that if they feel that something helps their symptoms or helps how they’re functioning, then that’s something that we would encourage them to do until better evidence is available.”
Still, he said, this approach “has to be integrated within a broader plan,” which typically includes pharmaceuticals.
Wahls, who still works part-time as a researcher at the University of Iowa, said microbiome testing can be helpful to track how diet and lifestyle changes change microbiome composition.
But, she recognizes “it’s not FDA approved. We don’t really know everything about how useful it is.”
Some folks might wait another five or 10 years until there is more data to support the testing. Others might want to dive in sooner.
“Both approaches are correct,” she said.
Terry Wahls pictured in her Iowa City home in 2026. Credit: Jess Craig/Straight Arrow.
For Wahls, jumping in headfirst proved the best approach. And while she only sees a handful of patients these days, she continues to share her story with those willing to listen. She spends her mornings exercising and sitting in the sauna. She gardens. She bikes. She is waiting for the back room renovation to be finished so she can install a pull-up bar and test her 70-year-old body.
But in many ways, her focus has shifted. She has a new grandbaby. Her son is running for state Senate. She is enjoying the years she once dreaded.
She hopes others can, too.
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