Skim milk is a low-calorie beverage that may be useful for a variety of nutrition and athletic goals, including bodybuilding and fat loss. Skim milk may be preferable to whole and reduced-fat milk because it contains no fat, but still provides protein, a nutrient that supports fat loss and muscle gain. While skim milk can support your goals, your entire diet and exercise routine will determine your success.

Skim milk can support fat loss because it contains fewer calories than other beverages. An 8 oz. serving of skim milk contains just 80 calories, while the same-sized serving of regular milk contains 160 calories. If you consume 2 cups of milk each day, you'd save 1,120 calories weekly by switching from regular milk to skim; this amount is enough to lose about 1/3 of a pound, independent of any other dietary changes. Skim milk's low calorie content can be detrimental for bodybuilding, as you'd have to drink nearly 3 cups of the beverage to support an hour-long weightlifting session, which burns 219 calories.

Skim milk is rich in protein, with 8 g of this nutrient per 8 oz. serving. Protein is beneficial for bodybuilding because it provides your body with the amino acids needed for muscle recovery and growth. Additionally, protein is beneficial for weight loss; a study from the April 2011 edition of "Nutrition Journal" found that high-protein diets were more effective for weight and fat loss than diets high in fiber, a nutrient that promotes satiety.

While protein is commonly considered the most important nutrient for bodybuilding, carbohydrates are important as well. Carbohydrates provide your body with energy, so it can help fuel your workouts. Each 8 oz. serving of skim milk contains 12 g of carbohydrates. A high carbohydrate intake may not be preferable for losing fat; research from the April 2011 edition of "The British Journal of Nutrition" indicates that high-protein diets that are low in carbohydrates produce more weight loss than high-protein, high-carbohydrate diets.

Skim milk does not contain any fat, which can be helpful for fat loss, as dietary fat is high in calories. If you are bodybuilding, you may prefer reduced-fat milk or whole milk, as the increased fat content will increase the calorie content of the beverage, making it easier to achieve the calorie surplus you need to grow muscle.

Some brands of skim milk are enhanced with vitamin D, which may be beneficial for both bodybuilding and fat loss. A study from the March 2011 issue of "Hormone and Metabolic Research" suggests that boosting vitamin D consumption can increase testosterone levels. Testosterone is a powerful hormone that promotes fat loss and muscle gain.