What do you do if you're attacked? You raise your shields and/or fend off the attack, then you reinforce yourself! Most of the time it's fight or flight when you approach something aggressively.
Shaming will in most cases do the opposite of what many people think it will. You think they'll feel so bad about it that they'll change, wrong! They won't fight their weight, they'll reinforce their view and fight you instead.
I tried for years changing my mother for her own good, lead to nothing other than unnecessary drama and stress. You CANNOT change someone who is determined to not change. If they want to change then shaming is still not the solution, that's still the worst thing you could do.
You should spend way more time supporting and reinforcing good behavior than shaming bad ones.
The only thing you achieved was to alienate your own mother, the only thing she'll change is your presence in her life. If she ever does lose weight you'll have an even harder time reconnecting, because it certainly wouldn't be because of you.