In people using progestin-only contraceptives, most studies do not show an increase in weight or body fat, but some do show a small increase (11). Some people will gain weight on birth control, and some people may be more prone to weight gain than others.

Why does progestin cause weight gain?

Progesterone is a natural hormone that regulates your menstrual cycle along with the hormone estrogen. This additional etonogestrel disturbs your body's natural hormonal balance, which can cause weight gain.

Can progestin help with weight loss?

In all these effects note that progesterone does not directly cause weight loss. Instead it reduces the effect of other hormones in the body which are causing the weight gain. Think of it as allowing rather than causing the body to lose weight.