from past reading I was under the impression that bone marrow was very high fat but haven't caught a single mention of Roland cracking those bones open, or for that matter any of the rabbit eaters trying to get any marrow out of the rabbit bones. they shouldn't need to by this point though. That lake has great fatty fish and they can be caught. One thing that this show has reinforced for me over the years of watching it, is that humans get very unmotivated when the hunger is sated. they catch a rabbit or two, or a couple of fish and they head back to camp, get a full belly and start whittling some useless trinket. IMHO they should be using the energy from that meal to go out and get more food. When you have 3 to 4 weeks of food prepped and stored - then you can whittle yourself silly if you want.
I realize it could just be the editing of the show, and also there is the mental factor that their brains are not firing on all cylinders by this time, but it does seem to be a common theme.