Remember the principle about this whole paleo idea is unprocessed things more or less as they come from nature! Now, whether you consume dairy at all is indeed a side issue and up to you, but the underlying idea of all the food we consume is that it is something we have evolved with, as close to its nature as possible. Skim milk, i would argue, is the opposite of this principle.

The problem with skim-milk is that they add milk powder to it.

Milk powder is a an undesirable ingredient because it is often produced via a process called "spray drying".

Spray drying is "no bueno" because the liquid is atomized (essentially shot out of a high-pressure nozzle) which increases the surface area exposed to the high temperature gases used to dry the liquid. This results in high levels of oxidized cholesterol.

If you want "skim milk", just make it at home by pouring the cream off of unhomogenized whole milk (grass-fed, etc.) You can add the cream to your coffee and use the rest for whatever you use milk for.

Spray Dryer Schematic From Wikipedia.com

Laboratory-scale spray dryer. A=Solution or suspension to be dried in, B=Atomization gas in, 1= Drying gas in, 2=Heating of drying gas, 3=Spraying of solution or suspension, 4=Drying chamber, 5=Part between drying chamber and cyclone, 6=Cyclone, 7=Drying gas is taken away, 8=Collection vessel of product, arrows mean that this is co-current lab-spraydryer

Why would you chose skim milk? Unless it's a taste reason, I can't see what NOT chose whole milk. More nutrients and those nutrients are more bio-available. Actually, chose whole un-homogenized milk- there is evidence that the homogenization is what damages the proteins. For my friends who don't like the globs of fat in this milk, I skim it off and use it to make butter...it's like making your own skim milk but not as harsh of a industrial process.

Pasturized skim milk is probably bad for you. Everything good in milk is deactivated or removed, leaving only the bad. The good include the undenatured whey, the various immune enhancers and pathogen defense mecahnisms, lactase, and high quality fat (CLA, saturated fat, medium chain triglycerides, monounstatured fat, and balanced --but low-- polyunsaturated fat). Skim milk has casein (a potentialy troublesome protein) and lactose (not a particularly good carb).

Skim milk is oxidized cholesterol. In fact any low-fat dairy is oxidized cholesterol because the processing to make any lowfat dairy oxidizes the cholesterol! In animal studies oxidized cholesterol produces heart disease and cancer

http://shine.yahoo.com/channel/food/is-skim-milk-making-you-fat-2479492/

All the dairy I have is full-fat grass-fed non-homogenized.

I recommend working your way from skim, 1%, 2%, and then to whole milk to get used to the taste if whole seems too heavy. My family had no trouble adjusting to whole yogurt, heavy cream and cheese!

if grass fed- a big YES. Skim milk isn't even milk. If you can get Raw- drink that.

I think all skim milk is a bad option, grass fed or not.

This article explains why skim milk is bad: http://naturalbias.com/why-skim-milk-isnt-as-healthy-as-you-may-think/