Why does my overweight mom feel compelled to 'advise' normal-weight me?

My mom loves to give financial advice even though my parents' finances are a five-alarm dumpster fire. Some of it's actually even good advice, just clearly not anything she was ever capable of implementing herself, for whatever reasons. She's a brilliant woman, but being motherly and acting in financially savvy ways were not things she actually did, even if she was aware of how they should ideally be done.

My dad dislikes my DH (for good reason) and sometimes can't help himself from commenting or giving advice (this usually happens when I make the mistake of venting). My parents are still married, but they are not the married-for-45-years couple you look to for marriage advice, unless the advice you want to hear is "it's cheaper to keep her/him" and "sometimes one or the other slept with other people, but we just pretended everything was fine."

The difference between the two, though, is my mom genuinely is trying to be helpful with her advice, and her advice usually isn't really wrong. My dad, however, loves to hear himself talk and thinks he knows everything but his advice is often not helpful. Neither seems aware of their own hypocrisy, but for different reasons.

Your mom might be like one of my parents, or she may have other reasons. I get it, it's so obnoxious and the hypocrisy is nauseating. Not to mention, they could be giving the greatest advice in the world but it can't override the decades of horrible modeling they provided. I usually change the subject or say I have to go. Then I don't talk to them again for awhile.