I've read from a few different sources that consuming anything aside from water within two hours of bedtime throws off your hormonal cycles and thus makes it more difficult to regulate your weight or have successful weight loss.
I'm no expert but I am a bit of a fitness fanatic. Lets see if I can reiterate what I remember:
You want to keep your protein and fiber intake up thru-out the day because fiber and protein decrease the amount of the hormone Ghrelin (hunger stimulator - makes your stomach growl and you feel weak) that your body produces. This way you put off cravings and don't eat high calorie / low nutrition fast fix foods.
Ghrelin is also the hormone that tells the body to direct it's energies away from digestion and toward repairing itself, thus leaking "repair and rest" hormones into your system. Ghrelin levels only elevate when you are nearing the end of a digestion cycle so...
You want Ghrelin levels to be higher at night because you're not usually thinking about or willing to to get out of bed to eat once you've laid down. When you are asleep your body is repairing the damage you've done to it thru-out the day, but only if your Ghrelin levels are elevated. If you work out (and if you want to lose weight permanently, you must) you have broken down your muscles during the day, you need them to be rebuilt while you sleep so you can be stronger and have more lean muscle mass which will lend to improved metabolic function, meaning you are on your way to no longer struggling with weight issues.
So if you consume something, especially something high in protein (which takes longer to digest than complex carbs like fruit and whole grains) right before bed, you are turning off your body's natural rebuild functions and hormonal balances because it is focusing on digestion.
I wouldn't do it. I would find the right balance of multi-vitamins and diet combined with an exercise schedule that will produce healthy permanent weight loss and muscle gain. You may want to look into finding other protein supplements that you can consume during the day that will help keep you full and satisfied.
Good luck and if you live in the East Valley or Glendale near the 10 and the 101, I can recommend a top-notch health club that will help you reach your goals!