Once-A-Week Workout

It might not look it but Katrina Szish says it's the toughest workout she's ever had. And she used to be an aerobics instructor.

She works out just once a week for only 20 minutes -- very slowly and quietly. It's a time saving regimen ideal for busy people that's getting a lot of attention, reports CBS News Correspondent Richard Schlesinger.

"Twenty minutes a week, you know, once a week, and I'm seeing all these results," she said.

And if a regimen like this sounds too good to be true?

"I believe in this only because it's worked," Szish stated firmly.

Conventional exercise is a lot noisier and takes a lot longer. Katrina's trainer says the old way is a waste of time. The new way is a wise use of time. The theory is: slow exercise with heavy weights builds muscle that burns fat faster.

"We all think that we have to endure all this exercise to get fit. You don't," said fitness trainer Adam Zickerman.

Oh, yes you do according to most cardiologists who say you should exercise at least two or three times a week for hours, not minutes. And it should be strenuous enough to get the heart going. That's what some specialists say.

Here's what Adam Zickerman says: "Cardio doesn't burn a lot of calories -- maybe 150 calories tops in an hour of very intense cardio which adds up to maybe three Oreo cookies."

Zickerman says the new way builds muscle faster which makes your body burn those Oreos faster.

"Well, my approach to teaching is not eat Oreos at all," said Delores Munoz.

She teaches exercise the old fashioned way -- it's noisy and sweaty and takes an hour a day. And it works for her.

"Twenty minutes a week. I really don't believe that you'll get the results that you need," she said.

But take a look at this. In her own quiet way Katrina has slimmed down and toned up following Adam Zickerman. And while you might find fault with him you won't find fat on her.