Well, I'm certainly no expert.. but I can share with you what I've learned through my own research and my trainer's recommendations..

The EM2WL plan suggests 40/30/30 in an effort to ensure we all get enough protein and healthy fats to support an exercise plan that incorporates strength training including heavy lifting. This is different from the typical "lose weight quickly" plan that MFP calculates. The difference is that when you are doing strength training your body needs a significant amount of protein to actually build muscle and become stronger, and most fitness & nutrition experts I've read recommend around 1.5g of protein per pound of bodyweight every day. For me, I try to eat around 150g protein every day and I weight 133 lbs.

As for the fats, your body needs healthy fats in order to function properly and, again, build muscle. This is not butter and fried food fats.. this is your olive oil, safflower oil, avocados, raw nuts, nut butters, etc.

Personally, I follow a 40 c/35 p/25 f macro plan, which works for me. I hope this helps! Good luck!