Thinman, if you are doing labouring jobs, (that is I assume pretty hard physical work all day) Then you must eat PLENTY , and preferably all throughout the day, in regulated amounts - whatever your wallet allows....
I used to do various jobs like that, one job in Aug2001 involved moving 25kgs maize sacks off a conveyor belt, almost non stop they would arrive, and then stacking them into a freight container.... During the time I worked there, I just couldn't train after work-- but I wasn't eating enough (nor sleeping enough), so had I got those things right, who knows.....
In the last three months I've been doing metal work (including some heavy forge work with the power hammer) But I've been feeding myself up much more("eating like a pig"), including in mid morning and mid afternoon. So I've kept my weight up and even increased it. Training is far better too...
Best to refer to others here about what you need to eat....(They've got more experience)
Nick