A Trainer to the Stars Who’s a Star-to-Be

If there’s a celebrity body you admire (Rihanna? Halle Berry? Ryan Gosling?), there’s a good chance it’s the trainer and nutritionist Harley Pasternak’s work, and it is equally likely that he has appeared in a magazine (ranging from People to Seventeen to Men’s Health) or on television to describe how he does it.

Mr. Pasternak’s fourth and latest book, “The Body Reset Diet.

Jennifer Hudson and Rihanna, former clients; and Kim Kardashian, a current one.

Mr. Pasternak, a 38-year-old Canadian, has undergone a makeover himself. Though he was once a body builder in the model of his hero, Arnold Schwarzenegger, “going on the ‘Today’ show a lot I thought it would be better to have an aesthetic that was more aspirational,” he said. “I didn’t want to be the guy with no neck.” So over the last few years, he has shrunk his 5-foot-10-ish frame from 240 pounds to 210.

The key to his success: Mr. Pasternak’s Five Factor plans: five-minute recipes with five main ingredients and five weekly 25-minute workouts organized in, yes, five-minute increments. And help from the dizzying array of products he endorses, including Ace bandages, Fitbit pedometers and the Coca-Cola Company’s Smartwater. To go with his fourth and latest book, “The Body Reset Diet,” which involves three smoothies a day in the first five days, he is creating his own blender. He may undercut his own business, since he is also developing with Shaklee Corporation, a direct-sales company, a just-add-water powder meal replacement that won’t require any appliances.

“I see myself as a problem solver, creating solutions,” Mr. Pasternak said of his growing empire. With two degrees in nutrition and kinesiology (rare for a celebrity trainer) along with a stint researching caffeine and performance-enhancing supplements for the Canadian military, he said he sees it as his mission to stop what “you’ve been doing from the DVD you bought on TV” (his own, available on QVC, apparently excepted) “to the ridiculous blood typing” and caveman diet.

If his latest offering, an abstemious 1,200 calories a day (most of which come from smoothies) sounds equally crazy to you, Mr. Pasternak pointed to a study that he said showed people who lost the most amount of weight at the start of a weight-loss program are exponentially more successful long term.

Dr. Michael G. Perri, the dean of the College of Public Health and Health Professions at the University of Florida and an author of the study done in 2010, wrote in an e-mail that the findings were “correlational,” and “cannot allow us to draw a definite conclusion” about what caused success. For example, high motivation, rather than rate of weight loss, could be the reason, he said. (Mr. Pasternak argued that seeing results faster is motivating.)

The diet is partly Mr. Pasternak’s attempt to convert the quick-fix crowd. “The average American wants a book on: ‘How do I lose 10 pounds this week?’ ” he said, insisting the latest studies gave him “permission” to depart from his previous, mostly moderate options. His plan calls for followers to use the Five-Factor approach, which includes 25-minute sweat sessions, 10,000-pedometer-counted steps daily and two “cheat meals” a week.

His own splurges: white pizza at Vito’s in West Hollywood and French fries. He paused when asked the provenance of the latter. “I don’t want to sound too fancy, but Soho House,” he said, the last two words in a near whisper. He paused, searching for a more aw-shucks option. “Gosh, McDonald’s French fries?”

Jordana Brewster, an actress on “Dallas” whose cheats include martinis and Tootsie Rolls, began working with Mr. Pasternak about six years ago.

“I went to all these trainers and nutritionists who would tell me, ‘If it tastes good, get it out of your mouth,’ ” said Ms. Brewster, 32. “I would live on protein bars and shakes, lose a bunch of weight, and then gain it all back when I wasn’t working. Harley is nice and mellow and smart, and what he tells you to do is sustainable.”

Mr. Pasternak is mostly quiet about which clients follow all or part of the new program. This could be because, as he acknowledged, he practically needs a law degree to figure out which clients he can speak about on which topic (his client Jessica Simpson once followed his diet, but now she is a Weight Watchers spokeswoman) and which products he needs to appear with, and when.

“Through making a lot of errors — — ” he started to say, then abruptly switched the conversation back to the zero-calorie beverages he endorses. While speaking with a reporter recently, Mr. Pasternak, who offers “Harley Pasternak’s Hollywood Workout” on Microsoft Xbox 360, left his red Microsoft Windows phone on the table. When he excused himself to call his wife, Jessica Hirsch, a real estate agent whom he met backstage in 2009 at his client Lady Gaga’s concert in Toronto, the phone he was promoting sat there. “I have two phones,” he said, then quickly added, “I have one phone,” and winked as he pocketed his BlackBerry.

Mr. Pasternak, who grew up playing hockey in Toronto, has been courting celebrity almost as long as he has been hitting the gym. At 13, his mother bought him three sessions with a personal trainer because she would see him “grunting and dropping weights,” he said, and was afraid he would hurt himself. At 18, he started taking on clients, the summer after his first year at the University of Western Ontario.

Soon, he sought out Dr. Marvin Waxman, who for more than 30 years has done the insurance-company-required medical assessments for most Toronto films. Dr. Waxman recalled, “He said he wanted to get in touch with me because I was meeting all the stars and he wanted to get involved training them.” Dr. Waxman began recommending him: “He had some good degrees that made him different than a lot of trainers. And he seemed like a good personable guy.”

His first client who was an actor was Jim Caviezel, for a 2001 movie called “Angel Eyes,” featuring Jennifer Lopez. Next came Stephen Dorff, whose transformation from, as Mr. Pasternak put it, “party boy who didn’t work out to really ripped” remains one of his favorites. In his office, Mr. Pasternak displays a snapshot of a shirtless Mr. Dorff from the film’s screen test. “It’s a Polaroid so you know there’s nothing touched up or doctored,” he said.

Mr. Pasternak said he was approached to train Ms. Berry for the film “Gothika,” but the producer Don Carmody, who had a small budget for a trainer, but not for housing and travel for one, remembered that Mr. Pasternak asked him about the job. “Harley then said he’d put himself up in Montreal and get himself there if I hired him,” said Mr. Carmody, who credited Mr. Pasternak with helping him lose 45 pounds. “He’s a very driven individual.”

At the time, Ms. Berry was fresh off her Oscar win for “Monster’s Ball” — and her now infamous appearance in an orange bikini in the James Bond film “Die Another Day.”

“I can get anybody to lose weight,” Mr. Pasternak said. “But how do you take the woman who had the best body in Hollywood and make it better?” After “Gothika,” he trained her for “Catwoman,” which required him to move to Los Angeles, where he has stayed.

Ms. Simpson, 32, whose ex-boyfriend John Mayer, the singer, was Mr. Pasternak’s client first, said, “In a lot of ways, I respect him so much that I end up working harder because I want him to be proud of me.”

These days Mr. Pasternak no longer tours with U2 or Kanye West or cooks frittatas for Ms. Berry on her film trailer stove. He designs programs, but deploys his staff to carry them out. “I don’t have to be the Vanna White of counting reps, like 1, 2, 3, now onto the next one,” Mr. Pasternak said. After all, he has companies to speak to (“interesting partners to create new solutions,” he called them) and 10,000 steps to go before he sleeps.