Women like the "no makeup, no men, and no mirrors" philosophy and 30-minute workout regime: Curves has grown exponentially since its first location launched in Texas in 1992. It now claims 10,000 locations in 70 countries and 4 million members.
The overhead costs are pretty low, but the investment can be risky. Curves' fast expansion goes hand in hand with a relatively high churn rate, and almost 16% of its SBA-backed franchise loans this decade failed. The company topped Entrepreneur magazine's annual "fastest-growing franchises" list in 2003 and 2005, but this year, it didn't make the top 100.