Dresses with peplum details by designers from H&M to Louis Vuitton can make midsections look thinner, says Verdi. Pear-shaped? Try a tailored ruffle made from minimal material "to deemphasize hips," he suggests. Have a straighter figure like Dakota Fanning (in Elie Saab)? A gathered flare adds volume to create a sexy, hourglass silhouette.