The pill could be exerting subtle influences on fat – particularly where it is stored in the body. At puberty, oestrogen and progesterone are responsible for the development of typically 'female' characteristics, such as wider hips and larger breasts, largely by changing the way fat is distributed.

Does birth control make you thick?

It's rare, but some women do gain a little bit of weight when they start taking birth control pills. It's often a temporary side effect that's due to fluid retention, not extra fat. A review of 44 studies showed no evidence that birth control pills caused weight gain in most women.

Does birth control change fat distribution?

Hormonal birth control (birth control that contains estrogen and/or progesterone) can cause changes in the body, such as changes in body fat distribution, bloating/fluid retention, and reduced muscle mass.