Your goals:
1) Fat loss: Obviously, you could just cut calories. I hate counting calories though so my first recommendation would be to lower carbohydrate intake as (simplified) carbs lead to sugar which leads to fat storage. I'm not sure how intense your workouts will be but you probably don't need a truckload of carbs (I actually train fasted and I'm currently running a ketogenic diet though I am heavier on the protein).
check out
http://www.leangains.com he's got a pretty interesting take on things but I've recently parted ways with his methodology.
2) Muscle retention: If you are working out, don't worry about it. Your muscles don't atrophy unless you really don't use them. That's why maintaining muscle is easier than putting it on.
3) Quick Recovery: Firstly, don't worry about over-training. Mostly a myth. I have two rules regarding training:
A) Lift Heavy Shit
B) Stay out of the pain cave
Pain =/= soreness. Soreness is an obvious side-effect of lifting weight (lactic acid and what-not, but I haven't actually looked into the science of soreness in awhile). Pain is your body telling you something is fucked up (but I'm sure you knew that).
Check out ChaosandPain.blogspot.com. His attitude toward working out is hilariously entertaining as well as scientifically proofed. He does his research.
I agree with his supplement ideology (that you don't need most of that crap). The only thing I recommend is A) protein because it's difficult to eat enough of it through food (but since you're not looking for muscle gain I'm not sure you need too much) and B) A multi. I take a regular multi but on some training days I'll use an Animal Pak multi-vitamin (
http://www.animalpak.com/html/sections.cfm?ID=7) which is every vitamin you'll ever need and 400 times the amount of it you'll ever want. I literally had a body high once when I took that without food, it was insane.
As you always should, get your fucking sleep. If anything, make sure you get your sleep. Super important.
P.S. I read somewhere that the company that owns Mens Health produces a lot of the vitamins and supplements they push.
---
On another note, muay thai sounds awesome. Have you ever seen Tony Jaa's movies? (ong bak/the protector)
---
Edit: @Mikeymike read this:
http://en.wikipedia.org/wiki/Naringin. Naringin is the culprit behind the "citrus bonus."