It's a blend of Whey and Casein Proteins
The "fats" in the Muscle Milk are followed by an asterisk.
It says at the bottom that the The fat in Muscle Milk is burned for energy and the fats which are called "Lean Lipids" actually help burn fat rather than store it.
The "guy" at the gym is an idiot
read about it here
http://www.cytosport.com/Product.aspx?ProductID=1
I used to take muscle milk when I was financially stable but it's too expensive for me now.
If you have the money, by all means, it's a great protein.
I only took it before my workout and before bed because the Casein Protein is slow digesting.
If you're looking for a quality whey protein cheap, try this
http://www.bodybuilding.com/store/opt/whey.html
I've been using it for a while now.
Get the Vanilla Ice Cream Flavor and blend it with Milk, a Banana and a packet of Cinnamon Roll Oatmeal for a GREAT PW Shake