A protein shake is made by mixing protein powder with a liquid such as water, milk or a plant drink, usually in a shaker with a small sieve that reduces lumps. Depending on the liquid chosen, the shake differs in calorie content and taste.
In practice, the amount of liquid usually follows the manufacturer’s instructions on the packaging, and about 200 to 300 millilitres per serving of powder is often recommended. Some powders are easier to stir than others, more on this in the entry Mixability. Additions such as fruit, oats or nut butter can make the shake more filling but also change the nutritional values.
The guide Mixing a protein shake properly offers detailed instructions for preparation.
