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After his high blood pressure landed him in the hospital in 2015, actor and illusionist Penn Jillette went from 330 to 225 pounds – not using magic, but by making drastic changes in his eating habits.

“I was on six very powerful meds to bring the blood pressure down,” Jillette, 61, told PEOPLE last year. “My doctor said I needed to get my weight down, and if I brought it down 30 or 40 pounds. it would be a little easier to control. And then he said something in passing that completely blew my mind — he said, ‘If you got down to 230, you probably wouldn’t need any of the meds.’”

In his new book Presto!: How I Made Over 100 Pounds Disappear, Jillette gets into the specifics of his life-changing regimen. And it all started with … potatoes. The magician recently chronicled the origins of his weight-loss for Grub Street.

“In just a few months in early 2015, I lost 100 pounds. The way I did it was very extreme. I did a monodiet for two weeks, which could have been anything. I did potatoes because they’re funny. Could have been corn, could have been beans, but I didn’t want a lot of fart jokes,” he writes. “A monodiet is not very entertaining, or social. No one ever calls up and says, ‘Hey, Penn, I just landed in Vegas, let’s have a potato.’”

Then, for the next three months, he subsisted on salads and vegetables, but no fruits or nuts. Now, his goal is maintaining his weight-loss, and he’s been able to stay at his target weight for the past 17 months. “I’ve changed everything about how I eat. Turn on the TV, look at the billboards, read magazines — see all that food? I don’t eat any of that,” he writes. “I eat no animal products, no refined grains, and extremely low salt, sugar, and oil.”

Jillette says one of the biggest lessons he’s learned from his transformation is that he doesn’t have to be constantly eating. After eating “a handful of unsalted, dry-roasted peanuts with Tabasco sauce” in the middle of the night, he didn’t eat for the rest of the day, unless you count seltzer and decaf coffee. (We don’t.)

“When I don’t eat, I get focused and clearer and … well, happier. I took the day off from eating,” he writes.

In April 2015, Jillette walked PEOPLE through his typical diet, which consists of an “enormous salad” with vinegar as dressing for lunch (he usually skips breakfast) and a dinner of 3 pounds of greens and three servings of black or brown rice with a vegetable stew, along with lots of fruits for dessert and vegetables with vinegar or Tabasco sauce as a snack.

“I could probably have a steak or a doughnut every couple of weeks, but I just haven’t felt like it,” Jillette said. “When you’re feeling as bad as I felt, and you go to feeling as good as I feel, the temptation to go back to doing what you were doing when you felt bad is not very great.”