Kevin Smith lost roughly 90 to 100 pounds after suffering a massive heart attack in February 2018, dropping from around 250 pounds to approximately 130-140 pounds. He did it through a combination of a strict potato-based mono-diet to kick things off, a transition to a fully plant-based lifestyle, and regular hiking. As of 2026, he’s kept the weight off for over eight years.
The Heart Attack That Started Everything
In February 2018, Smith suffered what’s known as a “widowmaker” heart attack, caused by a 100% blockage in the left anterior descending artery. His doctor told him he would have died if he hadn’t canceled a comedy performance that night and gone to the hospital instead. That near-death experience became the catalyst for every change that followed. Smith had spent decades as a self-described overweight guy, and the heart attack made weight loss a matter of survival rather than vanity.
The Potato Diet: 17 Pounds in 9 Days
Smith’s first move was unconventional. His friend Penn Jillette, the magician who had documented his own dramatic weight loss in a book called “Presto,” recommended starting with a potato-only mono-diet. The idea is simple and extreme: eat nothing but plain potatoes for a set period to reset your relationship with food. Smith followed it and reported losing 17 pounds in just nine days.
This wasn’t meant to be a long-term plan. The potato phase served as a rapid jump-start, both physically and psychologically. By stripping food choices down to a single, bland option, it essentially eliminated all the emotional and habitual eating patterns Smith had built over a lifetime. It gave him early momentum and proof that his body could change quickly.
Going Vegan (With a Push From His Daughter)
After the potato phase, Smith transitioned to a fully plant-based diet, and his daughter Harley Quinn Smith deserves much of the credit. She was already vegan and, in her words, “made him go vegan” after the heart attack. “I didn’t really give him a choice,” she told People magazine. “There was no way that was not going to happen.” Harley guided him through the transition, helping him navigate a way of eating he had never imagined for himself.
Smith has been remarkably honest about not loving it. He told People he “never imagined I would go vegan” and that he “f—ing hates vegetables.” But he discovered an unexpected side effect: because so many plant-based options didn’t tempt him the way meat and junk food once did, he naturally ate less. “You don’t do a lot of passion eating or boredom eating,” he explained. In effect, his pickiness about vegan food turned into a form of intermittent fasting without any formal fasting protocol.
The cardiovascular benefits of this switch are well-documented. Plant-based diets improve insulin sensitivity, lower blood pressure, and reduce blood lipid levels. A low-fat vegetarian diet is the only dietary pattern that has shown actual reversal of arterial plaque buildup in clinical trials (when combined with exercise and stress management). For someone recovering from a 100% coronary blockage, that reversal potential is significant.
Hiking Runyon Canyon
Smith didn’t take up CrossFit or hire a celebrity trainer. His primary form of exercise was hiking Runyon Canyon, a popular trail in Los Angeles. He built the habit gradually and eventually strung together streaks of consecutive daily hikes, each one covering about 4 miles round trip from his door. After hitting 10 days in a row (40 miles total), he set his sights on 20 consecutive days, then 37. The consistency mattered more than the intensity. Walking 4 miles a day is low-impact enough to sustain after a cardiac event, but over weeks and months it adds up to serious calorie expenditure and cardiovascular conditioning.
How He’s Kept It Off
What makes Smith’s story notable isn’t the initial drop but the fact that he’s maintained it. By 2026, he had kept off roughly 100 pounds for several years, hovering around 130-140 pounds. His approach has loosened over time into what he describes as mostly vegan with some flexibility for real life, paired with low-impact exercise and ongoing heart health monitoring.
He’s talked openly about the psychological adjustment of no longer being “the fat guy,” an identity he’d carried for decades both personally and professionally. There have been small fluctuations along the way, which he’s acknowledged, but the overall trajectory has held. The combination of a powerful emotional motivator (nearly dying), a sustainable dietary framework (plant-based eating he can maintain even if he doesn’t love it), and a simple exercise habit (daily walking) has proven more durable than any crash diet would have been.