Phil will never lose weight. His ego prevents him from accepting the fact that he's looking increasingly grotesque, and his laziness prevents him from taking actions to improve his condition in any way. He will only get fatter, grosser, balder, and more disgusting with time. I said it a few months ago, but yeah - at his age, it's a real slippery slope. The next two years we could see him age way further than he did the past ten.
The fact that he isn't even trying to take care of himself says something of his so-called "relationship". Usually guys who find a new wifey at least try to get some exercise, some new clothes, a haircut.. Just a little extra to impress the new girl. But he seems to be doing absolutely nothing. Makes me think there might be something to that whole "Did Kat leave?" rumor.
Even if she's still there, the fact that he's changed nothing about his foul attitude or appearance suggest that he's certainly not happy. Just picture what it's like for Kat, travelling across the country to live in Leanna's dirty, abandoned room only for a bloated Phillip to whine to her all month about bleeding subscribers and not having video games to play. If she hasn't left already, she must certainly be having second thoughts.