Muscle Memory

[SimpleJoee]

I've been out of the gym since July last year, no reasons, just turned into a lazy cunt and started slacking. Weighed roughly 76kg average and I was pretty lean. It's been quite a while since I've quit, and haven't lifted any weights since bar the odd session every few months, then I just give up again. I can see that my chest/bi's/tri's and back have lost size, but no where near as much as I would've thought. Just by working in TNT as a tipper (taking all of the parcels out of the lorries that come in, 90% are items over 10kg, doing this for 7 hours adds up haha), I can see that some size has already started to come back? Obviously it's not the same as lifting weights and doing routines, but I can see clearly that I've thickened up in my upper body, and my arms biceps genuinely seem to have increased in size. Has this got anything to do with muscle memory at all? To note as well, my current weight is between 74kg and 75kg (varies from day to day between the two depending what I eat). Also working in TNT my diet is completely shit, but I don't put on any weight what so ever, just curious as to how these things work out.