On protein, barely any: every version provides roughly 8g per cup. Fat level changes calories, not protein in any meaningful way. So choose by goal:

• Choose whole milk when you want more calories per cup or prefer its taste. Whole milk may be useful when you need more calories in a smaller volume. Some research suggests full-fat milk may affect feelings of fullness differently from skim milk, but the evidence is limited, and greater fullness does not necessarily mean lower calorie intake later.
• Choose 1% or skim if you want to reduce calories while keeping a similar amount of protein, or if your doctor advised limiting saturated fat.

Your overall eating pattern, preferences, and health needs should guide the choice; neither option is automatically required for weight gain or weight loss.

Cow’s milk protein is approximately 80% casein and 20% whey. Whey is generally digested and absorbed more quickly, while casein tends to digest more slowly. Both provide essential amino acids and can support muscle protein synthesis. There is no single casein-to-whey ratio established as ideal for everyone; total daily protein intake and the overall diet matter more.

One cup of milk provides roughly 0.7–0.8g of leucine, an essential amino acid involved in signaling muscle protein synthesis. Leucine contributes to the muscle-building response, but adequate total protein, all essential amino acids, and resistance exercise also matter.

Compared with plant beverages: many almond and oat drinks contain less protein per cup than dairy milk (often around 1g and 3g respectively), while fortified soy beverages often provide a more comparable amount (around 7g). Exact values vary by brand, so compare labels for protein, calcium, vitamin D, and added sugar.

Whole milk contains saturated fat, so its place in the diet depends on a person’s overall eating pattern, health needs, and calorie requirements. Observational studies have not consistently found higher cardiovascular risk with full-fat dairy consumption, but these findings do not prove that whole milk prevents heart disease or that saturated fat has no effect on blood cholesterol. Associations between dairy intake and obesity also vary across studies. Milk provides nutrients including calcium, protein, and, when fortified, vitamins A and D; weigh those benefits alongside its calorie and saturated-fat content.

About 65% of adults worldwide have reduced lactose digestion. Common signs are bloating, gas, or discomfort after milk. Options include:

• Lactose-free cow’s milk: generally provides similar protein and other nutrients to regular milk, although products vary.
• A2 milk: contains a different type of beta-casein but still contains lactose, so it may not resolve symptoms caused by lactose intolerance.
• Kefir: fermented and may contain less lactose than regular milk, but the amount varies by product.
• Fortified soy milk: a plant-based alternative with protein content that can be comparable to cow’s milk; check the label for protein, calcium, and vitamin D.

• Organic vs regular: no meaningful nutrition difference; buy for farming practices if you care.
• Ultra-pasteurized: lasts longer unopened, with similar nutrition.
• For children: milk contributes nutrients needed for normal growth, but the appropriate type depends on the child’s age and individual needs; follow age-appropriate pediatric guidance.
• Storage: keep milk refrigerated at 40°F (4°C) or below, return it to the fridge promptly after use, and follow the package’s storage instructions once opened. Discard milk that has been improperly stored or shows signs of spoilage; a normal smell alone does not guarantee safety.