"The wrong-size bra makes you look shorter, older and heavier," says Linda "the Bra Lady" Becker, owner of Linda's Bra Salons
. The clasp should be on the loosest hook to begin with and made tighter as the bra stretches over time. "When it is on the tightest hook—that's when you know you need a new bra," says Becker. Since breast size fluctuates—due to weight gain, weight loss and hormonal changes—Becker suggests going for a fitting once a year and buying a new bra every six to eight months.