It is okay to not initially understand why something is oppressive. There is nothing inherently wrong with not knowing something. This society is not prone to teaching you. In fact, it encourages oppressive behaviors. That is why it is so important to take time to educate yourself about these problematic issues.
Do not tolerate, from yourself or others, jokes that make fun of anyone for anything that is harmful or out of their control. Ever. Period. Full stop. Not racist jokes, not sexist jokes, not homophobic or transphobic jokes, not jokes that make fun of people who have physical or mental disabilities or illnesses. Practice this now, and practice it deliberately. You should have a sense of humour, but this is NOT a sense of humour. Don’t do it. Ever. It’s never okay.
Simply put: you do not get to build a magazine around making women feel inadequate and then express astonishment and pity when they comply. This is the culture that Glamour and its ilk have helped to build — a culture that is relentlessly critical of women’s bodies, a culture that considers women’s bodies public property open to debate, a culture that trains women to turn this criticism on themselves, and to accept and internalize every comment, opinion, observation and judgment on their bodies no matter who it comes from, be it a parent, a friend, a boss, a significant other, or a stranger on the street, because they think they deserve it.