Try eating a lot more chia seeds. chia contains an ideal balance of essential fats, plus high-quality protein. It is known to build lean mass naturally. For best assimilation of the essential fats in chia, grind the seeds in a coffee grinder. Then mix in water, juice, a smoothee, or other foods. It is very satisfying (because of the fats), but also incredibly nutritious and health-building.  (If you're committed to eating flax, make sure to take extra vitamins because flax seeds don't have the built-in antioxidants that protect chia seeds from going rancid.)

Also, no one's mentioned coconut or coconut oil. Coconut does not contain essential fats (like chia), but is a perfect complement to chia since is a known health-builder. Coconut contains the 'good' saturated fats that are a healthy source of calories. One of these natural (i.e., non-hydrogenated) fats is lauric acid, the main medium-chain triglyceride (MCT) known for helping balance metabolism. Coconut oil tastes quite good fresh, but also is one of the most stable cooking oils available. Who knew?!

Actually, the Hawaiians and Samoans have always known. Recent studies show that Pacific Islanders, who consume many of their calories from coconuts, have very low incidence of heart disease and low cholesterol levels....and vibrant health.

I found a tasty food product called CocoChia made with organic chia and organic shredded coconut. It's available from HPDI: http://www.integratedhealth.com. They also carry raw organic chia seeds and raw organic coconut oil. Plus, they have lots of great recipes for using coconut oil and chia seeds.