Running Doesn't Mean You Can Eat Anything: What Marathoners Need to Know About Heart Health

Table of Contents

• Key Points
• Background: The "I'll Run It Off" Mindset
• Study Methods: How the Research Was Conducted
• Key Findings: What the Studies Discovered
• The Debate: Does Extreme Exercise Hurt or Help the Heart?
• Patient Stories: Marathoners Diagnosed With Heart Disease
• Clinical Implications: What This Means for Runners
• Limitations: What the Studies Couldn't Prove
• Recommendations: Practical Advice for Patients
• Frequently Asked Questions
• Source Information

Key Points

• High-mileage running does not erase the effects of a poor diet on heart health.
• In two studies, marathon runners showed no expected artery benefit; one found more plaque in runners than sedentary men.
• Cardiologists disagree on whether extreme exercise itself causes heart disease; evidence of a causal link is called shaky.
• A heart disease diagnosis does not necessarily end endurance athletics; plans should be individualized with a cardiologist.
• Runners with healthy weight, blood pressure, and cholesterol can still have plaque buildup, so diet and screening matter.

Background: The "I'll Run It Off" Mindset

Dave McGillivray, a 59-year-old runner who logs 10 miles a day, once believed his heart was untouchable. "I figured if the furnace was hot enough, it would burn everything," he said. That furnace metaphor—the idea that high-mileage training burns off any dietary sins—is common among endurance athletes. McGillivray, who has finished 130 marathons and several Ironman-distance triathlons, is a living example of why that thinking may be flawed.

Six months before this article was published, McGillivray was diagnosed with coronary artery disease (a condition in which plaque builds up in the arteries that supply blood to the heart). The diagnosis shocked and embarrassed him. He even regretted including a chocolate-chip-cookie recipe in his memoir about endurance athletics. "My first reaction was, I was embarrassed," he said.

McGillivray is the race director of the Boston Marathon, making him a high-profile example of a problem that doctors say affects many marathoners. Runners with high weekly mileage typically show favorable health markers that can mask real risks:

• Lower body weight
• Lower blood pressure
• Lower resting heart rate
• Lower cholesterol levels

These numbers often lead runners—and sometimes even their doctors—to assume their cardiac health is robust no matter what they eat. One cardiologist described the attitude as bordering on arrogance. "I will run it off—that attitude clearly prevails among the marathoners themselves, almost sometimes to an arrogance," said Dr. Paul Thompson, a veteran marathoner who is chief of cardiology at Hartford Hospital.

Study Methods: How the Research Was Conducted

Two key studies backed this article's central warning. The first, published in the journal Missouri Medicine, examined a very specific group: 50 men who had run at least one marathon per year for 25 years. Their heart health was compared against a control group of sedentary men who did not exercise regularly. The researchers measured levels of coronary-artery plaque—the fatty, calcium-containing deposits that can narrow arteries and lead to heart attacks.

The second study, published in the British Medical Journal, took a different approach. Researchers compared the carotid arteries (the major arteries in the neck that supply blood to the brain) of 42 Boston Marathon qualifiers with the arteries of their much-less-active spouses. The study authors stated their hypothesis clearly: "We hypothesized that the runners would have a more favourable atherosclerotic risk profile" (meaning they expected runners to have cleaner, healthier arteries). The design was clever—by comparing runners to their own spouses, the researchers controlled for many lifestyle factors like household diet and socioeconomic background.

Key Findings: What the Studies Discovered

Both studies produced results that contradicted expectations. In the Missouri Medicine study, the lifelong marathoners showed higher levels of coronary-artery plaque than the sedentary control group. In the British Medical Journal study, the researchers' hypothesis about runners having a more favorable risk profile turned out to be wrong—the runners did not show the artery health advantage the researchers expected.

These findings contribute to a small but growing body of research suggesting that heart problems in extreme endurance athletes may arise because of the exercise, not despite it. The concept is counterintuitive, since exercise is universally recommended for heart health. But some cardiologists now theorize that there is a threshold: beyond a certain amount of intense exercise, the heart may experience damage rather than protection.

Dr. Peter McCullough, a cardiologist at Baylor University, wrote an editorial in the same issue of Missouri Medicine summarizing the risks. "Studies support a potential increased risk of coronary artery disease, myocardial fibrosis and sudden cardiac death in marathoners," he wrote. Myocardial fibrosis (scarring of the heart muscle) and sudden cardiac death are serious concerns for endurance athletes, and McCullough's editorial put them squarely on the table.

The Debate: Does Extreme Exercise Hurt or Help the Heart?

Not all cardiologists agree that marathon running damages the heart. Dr. Aaron Baggish, a cardiologist at Massachusetts General Hospital who himself competes in marathons and triathlons, pushed back on the causal claim. "The science establishing a causal link between vigorous exercise and coronary disease is shaky at best," he said. Causal link means proof that one thing directly causes another—and Baggish argues that proof is missing.

Even so, Baggish makes a clear distinction between what exercise can and cannot do. "I've never once told a patient they need to run marathons or race triathlons to maximize health, as this is not accurate," he said. In other words, extreme endurance events are not necessary for optimal heart health, even if they aren't proven to be harmful.

The disagreement between cardiologists has real consequences for patients. A runner diagnosed with heart disease may receive completely different advice depending on which specialist they visit:

• Dr. James O'Keefe, a Kansas City cardiologist and former triathlete, believes sustained endurance exercise can damage the heart. His recommendation is conservative: no more than 20 miles per week at a modest pace.
• Dr. Paul Thompson and Dr. Aaron Baggish believe that many endurance athletes diagnosed with heart disease can safely continue doing marathons and triathlons—provided their medical conditions are properly treated.

Thompson argues that the risk of continuing must be weighed against quality of life. That perspective resonates with another prominent runner who faced a heart diagnosis.

Patient Stories: Marathoners Diagnosed With Heart Disease

Ambrose Burfoot, winner of the 1968 Boston Marathon and editor-at-large of Runner's World magazine, seemed like the last person who would develop heart problems. At 67 years old, he is 6 feet tall and weighs just 147 pounds. A lifelong vegetarian, he subsists mostly on fruits, vegetables, and nuts—though he also admits to eating "cookies and all dairy products—cheeses, ice creams etc."

"Last March I learned that I have a very high coronary calcium," Burfoot said. He added, "I have a condition perhaps similar to Dave McGillivray's." A coronary calcium score is a measure of calcified plaque in the arteries, detected through a specialized CT scan. A high score indicates significant plaque buildup, even in someone as lean and active as Burfoot.

Burfoot embraces Thompson's quality-of-life philosophy. "I subscribe to the old saw: 'Exercise—it might not add years to your life, but it adds life to your years,'" he said. He also acknowledged that the label "exercise addiction" might apply to him. "I'm not afraid to call myself an exercise addict. I have always been afraid of dying on a run. But the way I look at it now, it's not that running will have killed me. Running has enhanced my life immeasurably, but it could also 'trigger' a life-ending event that probably would have happened even sooner except for my running."

Clinical Implications: What This Means for Runners

The growing number of heart disease reports in runners is prompting some marathoners to seek out coronary artery scans—imaging tests that can reveal plaque buildup before symptoms appear. The medical profession is united on one point, however: high-calorie workouts do not confer a free pass to eat anything.

Runners who train several hours a day often think constantly about food—especially treats. When McGillivray ran from coast to coast in 1978, he often ended each day at a Dairy Queen. "It wasn't just replacing calories but a mental thing—that vanilla shake was my reward," he said. The psychological reward of food, not just the caloric need, is part of the endurance athlete's relationship with eating.

Replacing thousands of calories with purely nutritious foods is genuinely challenging. But after McGillivray's diagnosis in October, he radically changed his diet. The 5-foot-4 runner dropped from 155 pounds to 128 pounds—a change he now celebrates. Notably, he did not cut back on training; he amped it up, boosting his weekly mileage from about 60 miles to 70 miles.

His story illustrates a key takeaway: a heart disease diagnosis in an endurance athlete doesn't necessarily mean the end of endurance athletics. It means the athlete's health plan must become individualized.

Limitations: What the Studies Couldn't Prove

The research in this article has important limitations that patients should understand. First, the studies were small—50 marathoners in one, 42 runners in the other. Small sample sizes make it harder to draw firm conclusions. Second, these studies demonstrate an association between marathon running and plaque buildup, but they do not prove that marathon running causes plaque buildup. Other factors could be at play, including genetics, diet, or the possibility that some runners begin endurance sports because of pre-existing cardiovascular profiles.

Third, the concept of an "upper limit" of exercise is theoretical and not universally accepted. As Baggish noted, the science establishing a causal link between vigorous exercise and coronary disease is shaky. Patients who read alarming headlines should remember that the existence of risk factors (like plaque) does not automatically mean a heart attack will occur—and the benefits of regular exercise for longevity and quality of life remain well established.

Recommendations: Practical Advice for Patients

Given the conflicting expert opinions, what should runners actually do? The cardiologists quoted in this article suggest a framework for decision-making:

1. Don't assume fitness equals immunity. Healthy weight, blood pressure, and cholesterol do not guarantee clean arteries. Runners who experience symptoms—or who have risk factors—should discuss heart screening with a doctor.
2. Take diet seriously. Medications and treatments can manage heart disease, but McGillivray's 27-pound weight loss shows that dietary changes can be significant even for very active people.
3. Consider an individualized conversation, not a "green light." Baggish explains his approach with patients: "I do not give patients (Dave included) green or red lights. We engage in an open discussion about known and uncertain risks and benefits and come up with a collective and very individualized plan about what is reasonable." In McGillivray's case, that meant supporting his plan to complete an Ironman-distance triathlon to celebrate turning 60—but with full awareness that his risks were elevated compared to a typical athlete.
4. Set a mileage goal by evidence, not habit. If you want guidance, know that recommendations range widely—from O'Keefe's 20-mile weekly cap to Thompson's and Baggish's position that treated athletes can safely continue endurance racing.
5. Watch for the warning signs. Coronary artery disease can be silently progressive, and sudden cardiac death during exercise is a rare but documented risk in marathoners.

McGillivray continues his tradition of running the Boston Marathon course after the last official runner crosses the finish line on April 21. He also plans an Ironman-distance triathlon for August, when he turns 60. His cardiologist supports this plan under the shared decision-making model—acknowledging the elevated risks while respecting McGillivray's goals. The story of runners, diets, and heart disease is still being written, but the central message is clear: you cannot outrun a bad diet.

Frequently Asked Questions

Can marathon runners eat whatever they want without harming their heart?

No. A study of 50 men who ran at least one marathon yearly for 25 years found they had higher coronary-artery plaque than sedentary men. Cardiologists agree that high-calorie workouts do not give a free pass to eat anything. Healthy weight, blood pressure, and cholesterol do not guarantee clean arteries, even in dedicated runners.

Does marathon running cause heart disease?

Cardiologists disagree. Some believe extreme endurance exercise may damage the heart, citing risks like coronary artery disease and scarring. Others say the science establishing a causal link between vigorous exercise and coronary disease is shaky. Studies show an association, not proof that running causes plaque buildup. Other factors like genetics or diet may also be involved.

I was just diagnosed with heart disease. Can I keep running marathons?

Some cardiologists believe treated endurance athletes can safely continue marathons and triathlons, weighing risks against quality of life. Others recommend a lower mileage limit, such as no more than 20 miles per week. The approach should be individualized through open discussion with your cardiologist, not a simple green or red light.

What are the warning signs of heart disease in runners?

The article mentions that coronary artery disease can be silently progressive, and sudden cardiac death during exercise is a rare but documented risk in marathoners. Specific warning symptoms are not listed, but runners who experience symptoms or have risk factors should discuss heart screening with a doctor. Fitness does not guarantee immunity from heart problems.

How much endurance exercise is safe for heart health?

Recommendations vary widely among cardiologists. One doctor advises no more than 20 miles per week at a modest pace, while others believe treated athletes can safely continue endurance racing. There is no universally accepted upper limit. Patients should have an individualized conversation with their cardiologist about known and uncertain risks and benefits.

I am a marathon runner with heart disease. Should I get a second opinion before deciding whether to keep running marathons?

Yes, a second opinion is valuable because cardiologists disagree on whether extreme endurance exercise harms the heart and whether runners with heart disease can safely continue marathons. Some advise a 20-mile weekly cap, while others support continued racing if treated. A diagnosis does not necessarily end endurance athletics, but your plan should be individualized. Since recommendations vary widely, an independent expert review can help clarify risks and options. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article: "Why Runners Can't Eat Whatever They Want" by Kevin Helliker, published in The Wall Street Journal, updated March 26, 2014.

Studies referenced:

• A study of 50 men who ran at least one marathon per year for 25 years, published in Missouri Medicine.
• A study of 42 Boston Marathon qualifiers compared with their less-active spouses, published in the British Medical Journal.
• An editorial by Dr. Peter McCullough (Baylor University) in Missouri Medicine.

This patient-friendly article is based on news reporting by The Wall Street Journal about peer-reviewed research and interviews with cardiologists. All statistics, quotes, and patient details are preserved from the original publication.