What a fascinating thread.
OP, I am sorry your DH is suffering with depression. As PP have said, the gaming is likely to be a way for him to hide from his feelings. It is on the whole even harder for men to talk about this kind of thing than it is for women. I have a (male) friend who is currently very depressed. He is on ADs and has attempted suicide. He struggles to talk about any of it, though I've found he will talk to me when we're doing something else practical. I hope your DH finds a way through this.
So far as your feelings about his weight are concerned: yes, of course it is shallow. But you were attracted to the whole package of your DH, and one major part of his attractiveness has changed. So it's not surprising that you don't feel the same physical attraction towards him. I suppose you have to give it a bit of time and see how things work out.
There are some seriously batshit comments on here ("Fun size" etc).
FWIW, I don't buy all this crap about weights going up and down, metabolism changing, 'baby weight' being impossible to shift, etc. If your weight goes up, it's because you're eating too much and not moving enough (unless you're on medication that causes weight gain, obvs).
I'm 49 and am exactly the same shape and size as I was when I was 19 (5 foot, 7 stone, flat-chested size 6-8). No flabby bits, despite having two babies who were 10lb plus. But if I did start to put weight on, I'd be doing something about it because I'd very soon look and feel like a whale.
All that said, my DH is very decidedly overweight (at least two stone, possibly three). However, he was like that when I fell in love with him, and it's part of his loveliness. In fact, I don't even notice it (except when his stomach gets in the way of my head when I'm giving him a blow job
).
I now wonder if I'd have fancied him if he'd been skinny. Perhaps not so much, as his overweightness is entirely caused by living very well. If he were a skinny teetotal fitness type, I would probably never have even spoken to him.