I wear pettipants under dresses to avoid "chub rub" between inner thighs.  My size is in the 20-s and I'm pear shaped, with inner thighs that bulge out (instead of in, as some fat distributions go) at the inner thigh.  These boxers were light & breezy as undies, but absolutely insufficient for chub-rub avoidance, for which I personally need at least 7" of inseam.