Relying heavily on the medium

“This is not an infomercial,” Paul McKenna told the camera last month in the first episode of his self-improvement show “I Can Make You Thin” (TLC, 9 p.m. Sundays). “This program is about you. I’m going to be talking through the television set directly to you watching at home. Yes, you.”

And sure enough, McKenna isn’t selling anything in this five-part series -- nevermind the books, DVDs and audio downloads available at mckenna.com -- though his show is a clever reimagining of the infomercial style.

Each week, in front of a studio audience, the British motivational speaker and hypnotist offers advice on how to lose weight and sets tasks for his at-home audience to complete. The show itself is important, but in McKenna’s view, what you do in between shows, on your own time, is the real take-away.

Call it prescription TV. McKenna is like an old-style snake-oil salesman, constantly espousing the magical powers of television. And episodes not only mirror infomercials in structure -- like the Ronco commercials of old, they feature a too-perfect, too-compliant studio audience barking out answers in unison -- they also have a whiff of televangelism.

McKenna is an aggressive abuser of the second person. “I’m gonna prove to you how well it works,” he said in an early episode, emphasized with a hand pointed at the camera.

McKenna, the show says, is “one of Britain’s most successful self-improvement authors.” He has no apparent training in nutrition or in any science for that matter. He’s prone to broad statements that sound authoritative but may or may not be wholly true: “It’s not just that diets don’t work -- they’re the reason why half of America is overweight. Diets are nothing more than training courses in how to get fat and feel like a failure.”

Last year, McKenna was cited by England’s Advertising Standards Authority, a watchdog group, for making unverifiable claims about the effectiveness of his weight-loss program.

To demonstrate his ideas, “Thin” features several experiments that amount to little more than sleight of hand. Some register as logical -- people will eat less when they are blindfolded and can’t see if they’ve cleaned their plate -- and others less so -- the woman who didn’t notice she was eating from a bottomless bowl of soup, in particular, strained credulity.

Additionally, each week McKenna introduces a success-story guest from his days peddling weight loss in England. They’re inspiring, but God forbid they’ve actually had gastric bypass surgery.

His weight-loss techniques, though, are not radical: Eat smaller portions, train yourself to walk regularly, create negative associations with foods you crave.

Most importantly, McKenna’s method requires you to be open to the power of suggestion. If you’re willing to listen and follow direction, he proposes, then all the traditional stuff such as calorie-counting doesn’t matter quite so much, if at all.

And if McKenna can persuade people to change their habits regarding food, it’s likely he can conquer the easier challenge of making them tune in to his show.

This makes “Thin” not only a rethinking of infomercials but also of the very idea of appointment television. In a climate where audiences are increasingly turning to DVRs and DVDs rather than keeping up with their favorite shows on a network-determined schedule, the idea of imposing time-specific tasks on viewers is an innovation, a way to try to ensure that they remain committed to a program and on the schedule the network and advertisers desire.

Oprah Winfrey too has learned the value of making an appointment. Her latest book club selection is Eckhart Tolle’s “A New Earth: Awakening to Your Life’s Purpose,” a wildly popular self-improvement text. And while she has used her show to discuss the book, it’s her embrace of online methods that have been most notable.

Every Monday night since the beginning of March, she and Tolle have led an online interactive discussion about the book, pegged to different chapters. The sessions will run through May.

Winfrey archives the sessions online (at oprah.com/anewearth), a slight undermining of the appointment idea.

But after a couple of years in which the balance of power has been shifted toward the user and away from network schedules, these new claims on viewer time are early indicators of a new way in which the networks will be fighting back, seeking to re-modify behavior, as McKenna would say, “through the television set.”