Ever wonder why celebrities (including Kim Kardashian
, who's been looking pretty darn amazing lately) constantly joke about their Spanx on the red carpet? Because they all wear them
. Supportive, super-stretchy undergarments can erase visible panty lines, smooth problem areas and banish muffin tops and love handles—something women at any size can benefit from. A few rules of thumb: If you're shopping for a dress you plan to wear with shapewear, bring said undergarments with you to make sure they're invisible underneath the look you choose; buy your shapewear in either nude or black (white works under surprisingly little); and buy the correct size (this goes without saying, but try it on before you purchase!). And speaking of undergarments, make sure you're wearing the right size bra while you're at it—many women aren't, and an ill-fitting bra can leave you with weird bulges or lines. No fun.