Should I make a protein shake with milk or water?

Milk if it’s a meal. A cup of 2% milk adds 8 g of protein and 122 calories, unsweetened soy milk adds 7 g for 80, and unsweetened almond milk about 1 g for 39. Water is fine when the shake is a snack beside your meals.

Water became the gym default for two reasons people repeat: it saves calories, and milk supposedly slows the protein down. Both make sense for a quick shake after training, next to a meal you’re about to eat. They work against you when the shake is the meal, because a breakfast in a glass needs a breakfast’s calories to last until lunch.

Milk in a shake is like bread in a sandwich. You could skip it, and what’s left would be a lot less of a meal.

Made with water

B+

With water B+

33 g protein, 326 calories

or

Made with milk

A

With milk A

41 g protein, 448 calories

What does each liquid add?

USDA numbers for one cup. The percentages are shares of the FDA’s Daily Value for calcium.

The surprise in that table is almond milk, which in the USDA’s record has more calcium than dairy milk and almost none of the protein.

Does milk make a shake a meal?

It helps a lot. Our chocolate peanut butter shake, the Ultimate, still clears a 165 lb adult’s 30 g line made with water, because the scoop, half banana, peanut butter, flax, cocoa and spinach carry about 33 g between them. But at 326 calories it’s under a meal’s size on a 2,000-calorie day (500 to 830), and that’s where you feel it by mid-morning. With a cup of milk it’s 448 calories and 41 g of protein, and it clears all six meters for an A.

At 165 lb the line is 30 g, and the Gyroscope app personalizes yours. A plain scoop shaken with water is 113 calories and 25 g of protein, which is a fine snack after the gym and a poor breakfast.

Does milk slow the protein down?

Extra calories slow the stomach a little, and in a meal that’s the point. In a 2016 MRI study, a thin 500-calorie shake took about 70 minutes to leave the stomach halfway, against 27 minutes for a thin 100-calorie one. More calories kept the stomach busy longer, and a shake that stays longer keeps you full longer. After training it makes no practical difference, since timing makes little difference for muscle.

What about oat milk?

Oat milks vary a lot by brand, so go by your carton. Pick an unsweetened one and count its protein from the label.