As I've stated before, I had the same condition as Fletcher and also had the surgery he has had.
Without surgery, the condition is dormant but when it 'flares' it massively impacts weight and fitness and vitality.
When I heard he was having surgery, I was more confident of his possible return than I was before he had the surgery.
If the surgery is successful, there is no reason why you cant get back to previous weight and fitness ... the surgery 'cures' the condition.
Would not surprise me at all to see him in the squad for pre-season and we take it from there.