Injectable, long-acting birth control methods like Depo Provera cause some women to gain a lot of weight. However, the average weight gain in one large study was just 8.1 lbs. in 2 years (13.8 lbs. in 4 years).
Although Depo Provera is a very reliable birth control method and the most recommended for teens or women who must not get pregnant for health reasons, women should be aware of the risk of excess weight gain and decide on a birth control method and weight control strategy with this in mind.
Birth control pills are another story. Today’s birth control pills are made with less hormones than ever before. Although some women gain weight when they begin taking them, in most cases the weight gain is minimal (less than 10 lbs.). More recent studies have shown the weight gain to be as little as 2-3lbs.