The problem is you can't separate mental health from physical health.
Of course those of us with robust mental health would of course, when injured, be watching our diet and doing what we could to stay in shape.
For people suffering with depression they have zero motivation to get to work, keep fit and usually over eat. And if your metabolism is such, then you pile on the pounds.
I've lived with someone like that. It's not their fault.
The failure of Tomlin is that he didn't get the right professional help and support and successive clubs have also not provided it.