PITTSBURGH -- If it seems like you see a Curves gym just about everywhere you go, you're right. In the last five years, 43 Curves have opened up in the greater Pittsburgh area. In fact, Curves is the fastest growing franchise in the world. But does it really get you fit?

Curves is a women's only, no frills gym, that fits the needs of busy women.

Lauren Boyd said, "This is a program that only takes 30 minutes out of our time."

That's right, the total workout time is only 30 minutes. Since Boyd's been going to Curves, she's lost weight and inches.

"Six and half almost 7 inches in all," she said.

The Curves program works by combining cardio and strength training. At Brenda Kurczewski's Curves, you see women of every size, shape and age. They move quickly around a circle of hydraulic resistance machines.

Kurczewski said, "It's a hydraulic workout. It's not using conventional machines which you find in gyms. Hydraulics work with a piston you create your own resistance, the faster you move the hydraulic the greater the resistance."

Every 30 seconds, a recorded voice tells everyone to move to the next station. In between each piece of equipment you jog in place before moving on to the next machine. In 30 minutes you do the circuit two or three times. But does it work?

The Curves program is being studied at Baylor University. The preliminary research is positive. It shows women in the study not only lost weight, but stuck with the exercise program. The drop out rate was lower than seen in other weight loss studies. And that, says Pittsburgh exercise physiologist, Leslie Stenger, is the key to success.

"We've got 60 percent of the population that doesn't exercise on a regular basis at a level intense enough or just frequent enough to gain the health benefits," she said.

Strenger said women have a harder time starting an exercise program.

"The barrier for women is they want a social environment and they are afraid of failure. Women are a little shy about coming into an unknown environment and getting started."

Curves has designed its program to break down those barriers.

"It's not all just about exercise. Friendships are built here. It's enjoyable," Kurczewski said.

And the "no men allowed" rule makes a big difference for many women.

Boyd said, "The best part is there are no men there. It's all women. You don't have to be something you're not."

Curves also offers diet and nutritional counseling at no extra cost. Gym owners said to get results women must workout at least three times a week. And Stenger said while this routine is good for beginners, as you become more fit it may not offer enough of a challenge.