I've not written many kind words about skim milk on this blog. In turn, I've dismissed it as tasteless, bland, insipid; and I've even dismissed its supposed health value.
But there is something to be said for skim. It is, obviously, less calorically dense than its more fat laden brethren. There. That is the good thing to be said for skim milk.
If you're trying to limit the amount of calories you consume in a given day, choosing a skim latte is one way to accomplish that goal. But choosing skim because you think saturated fat has some unique ability to make you fat is misguided. Sugar, of course, is much more deleterious to physique improving goals.
But really, it comes down to a very simple set of rules, borrowed from the bodybuilding.com message boards, and altered just a touch:
1) Eat enough protein. People will argue about how much this is, but I think 1g/protein per kg/body weight is reasonable. If you make it a priority to consume high quality (i.e. complete) protein in reasonable quantities at every meal, this will happen without counting.
2) Work out. If you want to look like you have muscle, you actually have to have muscle. That means lifting heavy things every so often. I think that the case for cardio is much stronger than the case against as well.
3) Consume an amount of food that is in line with your goals. If you want to weigh less, maintain a calorie deficit. If you want the opposite, do the opposite.
All of this is to say that a skim latte can be a part of a healthy and fit lifestyle; but it's not a guarantee of one either.