ILuvChubbyChix:
I'm not the OP, but I have tried Serious Mass powder. Except, mixed with half & half, not water.

I do NOT recommend Serious Mass. Not unless you like something you can't drink and wasting money.

The result was a mix that was SO thick, it was almost undrinkable. You just know that mixing it with cream will make it even harder to drink.

The cost is also extremely high for what you get. $20 for 4 servings, or 8 scoops worth. So, each scoop is about 625 calories.

You would be much better off purchasing Ensure Plus, which has 350 calories in 8 fl. oz. and tastes a lot like chocolate milk, and is just as easy to drink. Ensure Plus, as expensive as it is, would still be a better value. I should note both Wal-Mart and Kroger have their store brand knock offs which are much cheaper than Ensure. Those product names are Equate Plus and Fortify Plus, respectively.

You can even mix it with half & half, or cream with success, creating something that tastes a bit like melted milkshake yet with many more calories.

Of course, none of these mixes really have a lot of carbs, which really help and are essential for gaining.

If you really do want a powder you may be able to mix into a shake, or even cooking, you can order pure maltodextrin online. I'm not sure what kind of shops would stock that regularly. Oh and it'll be much cheaper than any of these mass gain powders.

The little bit of Serious Mass I do have left, I will probably mix with water so it won't be a complete waste, but I don't think I'm getting it ever again.