I think I can help explain it a little. If you're doing protein shakes, with regular protein powder, then I'd expect to see more like the numbers that the others listed in their powders. I knew that I've used Designer Whey brand before and it was in that general area, so I looked it up on their website. You have bought something more like the Kellogg's Protein water. Something like a Kool-Aid with protein? It has 6 grams of protein, and the 6 carbs are all fiber, which are essentially a zero carb effect because the body won't digest fiber. So look at this as a 40 calorie water with a boost of fiber and protein - which many people probably tend to lack some of when trying to diet. So it's still got benefits.
