Milkfat

The most common variety of milk consumed is cow's milk. Cow's milk is available in a number of milk fat percentages: skim (fat free), 1%, 2% and whole (where no fat has been removed).

Here's how they break down:
1 Cup whole milk 1 Cup 1% milk 1 Cup 2% milk 1 Cup skim milk
155 calories 112 calories 135 calories 93 calories
8g fat 3g fat 5g fat 0g fat
13g sugar 13g sugar 13g sugar 13g sugar
8g protein 9g protein 9g protein 9g protein
12g carbs 13g carbs 13g carbs 13g carbs

Cow's milk is a great source of calcium, so it will help promote strong bones. Moreover, each cup of milk contains roughly eight grams of protein, a nice boost to muscle-building.

The drawback to cow milk is that it contains sugary lactose, which many people are intolerant to, causing a variety of negative side-effects. Cow milk is an animal product. Those who would like to refrain from consuming animal products would probably choose not to drink it.

Also, if you're watching your weight or saturated fat intake, whole milk is not the wisest selection because the calorie and fats counts are higher.

However, cow milk is great for anyone who can tolerate lactose and who has no issues consuming animal products. By adjusting the fat percentage (skim, 1%, etc.), if necessary, cow milk can be a part of any diet plan.
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