TBH this sounds very much like a man I dated, but I took a very different approach. Rather than moan about him online, I used his greedy-gut habits to my own advantage and enjoyed many pleasant outings - and innings, for that matter.
Going out for a roast, I certainly wouldn't have left the house without a spare boat of hot gravy in my handbag. And to stop him wandering off for snacks, I'd always carry thermal bags filled with necessities like cheesy chips, lamb kebabs, curry and pizza. I soon had him performing all sorts of favours and considerate acts in return for tasty rewards, and I became skilled at storing treats upon my person - such as a whole string of saveloys up my sleeve, along with tubs of tasty dipping sauce.
Fun-size choc bars, unwrapped, were liberally strewn amongst my coiffure, and in the dance clubs other women would watch enviously while we slowly waltzed, with him seemingly nuzzling my curls, while in fact grazing on the Snickers and Mars etc.
I used the same tactics in bed, and soon had him performing all sorts of gratifying foreplay in return for specified treats - a fish finger for this, a pork chipolata for that, or if he came up with his own pleasing innovations, he might score a jam doughnut, or even a nice big gobful of warm gravy.
Sadly, the Covid epidemic intervened, the outings dried up and he returned home to his mother, who continued to spoil him rotten. Last I heard he was dating Gloria Bisto, heir to the Bisto Gravy fortune.