When you have sex, do your hips get wide or is that my body is already forming?
Having sex doesn’t make your hips get wider. In fact, there’s zero connection between sexual activity and body growth. Changes in your body like your hips or breasts growing are things that often happen naturally during puberty. It’s true that some young women start having sex around the time that those changes take place, so they make think that having sex causes those changes—but it’s just by chance that timing worked out that way.
However, pregnancy — which can result from sex — does cause changes in a woman’s body, like breast growth and weight gain.