Do you feel like women should stay single? Please women, stay single. Please women. When you commit to your man, commit to the gym as well.
Why would a woman need to commit to a gym as well as a marriage?
Because if you don't, you will gain weight after marriage
It sounds like you are saying that women need to prioritize efforts to maintain their physical attractiveness, and this isn't fair to women. They have many other responsibilities with their jobs and families, so they shouldn't only have to care about their looks, as this is only a small part of their personal value. You wouldn't criticize a man for gaining weight or losing muscle after high school, so women shouldn't be treated worse.
No I just want to give them advice for staying fit.
If you are going to give advice for staying fit, it's important to give the advice to both men and women. By directing this toward women, it appears you think women are only valuable for their looks and this is wrong.