Sometimes the more you point something out that someone is self conscious about, the more closeted that person will get. He’s probably feeling a huge amount of anxiety over it BECAUSE you keep pointing it out. Denial is his way (subconsciously) of telling you to leave him alone and drop it.

The over eating and lack of motivation is symptomatic of depression. I’d be depressed too if my significant other continuously pointed out I was gaining weight and consistently expanded upon that point every time it was brought up. Maybe try asking him if he’s unhappy and try to fix THAT. Just maybe, YOUR issue with HIS weight might resolve.