Claim 3: You can get "six-minute" abs.
How? Twice a week for three weeks, perform a short ab workout of just two movements, Ferris instructs. For the "Myotatic Crunch," sit on a balance ball so your rear end is about 6 inches off the ground. With your arms extended as far upward as possible, lean back, hold, and rise back up. Repeat 10 times. For the "Cat Vomit Exercise," get on all fours, keeping your back straight. Forcefully exhale, then hold your breath, pull your belly button in as far as possible, and hold for 8 to 12 seconds. Rest. Repeat 10 times. Ferriss says these simple exercises work a fuller range of ab muscles. The caveat—and it's a big one—is that you've also got to be on a strict diet (Ferriss recommends the one described earlier) and almost in the single digits of body fat percentage to see a cut six pack.
Experts say: It makes sense. "The most critical thing if you're trying to have a muscular abdomen is to not be fat," says Gary Hunter, a health education professor at the University of Alabama-Birmingham who specializes in exercise physiology and fat distribution. The exercises are important—especially if you want really defined muscles—but you've also got to get rid of any fat that's covering them, he says. So while the time working the abs may be just six minutes, a diet plan to go with it could be a much bigger commitment.