Eat as much good fats as you can.

By "good fats", I mean try not to go overboard with highly processed vegetable oils or fatty grain-fed meats because they have a lot of the omega 6 stuff that promotes inflammation.
I've been eating butter/ghee, virgin coconut oil, eggs, and lots of homemade yogurt made out of organic half-and-half (more butterfat than even whole-milk yogurt). Meats from animals that get to graze instead of eating grains also have "good fats", but in some parts of the world are quite expensive and hard to find.

http://inflammation911.com/omega-6-starts-inflammation-omega-3-stops-it/
http://www.truthaboutabs.com/grass-fed-beef.html
http://www.fitnessspotlight.com/2010/04/15/grass-fed-beef-meat/


One caveat with the coconut oil -- I learned from Light on this forum that you should not overdo it. It can make you feel kind of sick if you suddenly eat a huge amount. I melt a tablespoon or two and mix into my yogurt, or use a similar amount to fry an egg or two.

Note: I haven't figured out to actually gain weight on NSD; this is just to maintain. Have been the same (thin) weight for 6 months now, but at least I haven't shrunk to the cancer patient/anorexic build like I was afraid of. And, I'm feeling pretty good now, not even having to take over-the-counter NSAID more than a few times a month (do take boswellia anti-inflammatory supplements every day, but at least that doesn't lead to heartburn/ulcers/gut damage like NSAIDs).