Many women report weight gain when they use an oral contraceptive.
A woman can expect to gain 5 to 10 pounds when she starts using the pill, but this side effect has been highly dramatized in our overly weight conscious culture. Current forms of the pill have much lower doses of the hormones that may cause weight gain, making older reports of this side effect largely useless. A woman can control some of the weight gain related to water retention by reducing her salt intake and making sure she drinks enough water. It may also be the case that some women gain a few extra pounds when they go on the pill because they expect that weight gain, and thereby don't watch their weight as closely.