A University of Wisconsin-La Crosse study in 2002 found that even after eight weeks such machines produced "no significant changes in weight, body-fat percentage, strength or overall appearance."

And while some electrical muscle stimulators have actually received FDA approval, most of them were designed for medical rehabilitation and require a prescription.

The bottom line? The small print in ab belt ads suggest combining the belt with good old-fashioned exercise and eating right. Go ahead and try that, minus the belt.

Ab Rocker workout equipment

No. 2: The Ab Rocker

When you spend your hard-earned money on exercise equipment, you generally want one that will show results, right?

So why buy a product that's actually shown to be less effective than simply exercising without the pricey equipment? Ab Rocker users, care to field that one?

The Ab Rocker, a machine designed to work your abdominals through a rowing-like rocking motion, does provide some benefits. However, a San Diego State University study ranked it dead last in a test of 13 abdominal exercise products, branding it 80 percent less effective than the traditional abdominal crunch.

Fellow ab exercise machines the Ab Roller and the Torso Track performed a little better, but still were not much better than the basic crunch.

The results support the American Council on Exercise's stance that it's not necessary to spend big bucks on ab exercise machines. Instead, ACE recommends that if you are going to invest in a piece of equipment, make it a high-quality exercise ball.

Suzanne Somers ThighMaster

No. 1: ThighMaster

If you watched TV at all in the 1990s, it was nearly impossible to avoid Suzanne Somers -- and we're not talking "Three's Company" re-runs.

The idea used to sell the ThighMaster was simple: If Somers has great legs and she uses the product, it must work.

Just one look at Somers' thighs, or watching the men in their lives paying a little too much attention to her infomercials, was enough to send women scrambling for the phone and their credit cards.

No doubt the $20 piece of equipment, which was basically a spring-loaded, foam-covered piece of metal, ended up in the back of a closet or in a yard sale before too long.

That's because, as any health or fitness expert will tell you, working out a specific area of your body won't melt the fat away there. Sure, the ThighMaster might make the muscles in your thighs firmer and stronger, but it's not the miracle fat-burning cure many were hoping for.

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