check out this thread for starters:
Curves or regular gym?
Also, according to this article titled "ACE Puts Curves to the Test" (find here ==> http://www.acefitness.org/getfit/curves.aspx
) it doesn't.
Researchers found that the total 30-minute Curves workout burns an average of 184 calories, while the 25-minute circuit alone burns 163 calories. "Intensity-wise it's similar to walking four miles an hour [for 30 minutes] on a flat treadmill," says Greany. "So it's a moderate-intensity workout."
If you read the article linked above, the researchers had the study participants refrain from speaking with other members - I know that the franchise is advertised as somewhat of a social club but if you spend more time chatting, that's taking away from your workout and you will be apt to burn even FEWER calories that quoted above.
While Porcari notes that the data for Curves is "dead on" with other studies on circuit training, he expects some people will be surprised by the relatively low average total caloric expenditure of the Curves workout. "It might be kind of a wake up call that half a Krispy Kreme donut is all that it takes to negate the effect of a Curves workout," he says.