Medium chain fatty acids (coconut and palm fruit oils) from the diet are required to "activate" ghrelin so it can interact with its receptor GHS-R1a I believe it is called. This receptor then turns on the release of growth hormone which is responsible for a lot of things such as bone mineral density, memory and learning as well as many other things. The thing is that I found so cool about the science behing Ghrelin is that we really don't know much about it. One thing we do know is that 90% of the ghrelin in circulation of a average adult is not "activated" and can never interact with the growth hormone recptor. So if you get enough medium chain fatty acids in your diet you can increase that 10% "activated" number easily because the normal western diet is dreadfully low in these MCFA. Medium chain fatty acids examples are coconut oil and palm fruit oil. It is fatty acids that have between 8 and 12 carbons in its chain, that is what makes them medium instead of short or long chained.