Whey Protein

What It Does

Leucine signals through mTORC1 to start translation of new muscle protein, and whey raises plasma leucine faster than most other proteins. At rest and after resistance exercise, hydrolyzed whey stimulated more muscle protein synthesis than casein or soy in young men, which the authors attributed to faster digestion and higher leucine content (Tang 2009).

How much per meal depends on the setting. After leg exercise, muscle protein synthesis plateaued at about 20 g of ingested protein in young men, and 40 g mostly increased amino acid oxidation (Moore 2009; that study used egg protein). After whole-body training, 40 g of whey outperformed 20 g (Macnaughton 2016). Older adults show anabolic resistance and need more per meal for the same response.

Over months, the effect is real and modest. A meta-analysis of 49 trials found protein supplementation added about 0.3 kg of fat-free mass and small strength gains to resistance training, with the benefit leveling off around 1.6 g of total protein per kg per day (Morton 2018). The post-workout "anabolic window" is mostly a myth: in a timing meta-analysis, the apparent advantage of protein near training disappeared once total daily intake was matched (Schoenfeld 2013). Hitting the daily total matters more than timing.

Populations who benefit most are those who struggle to reach their protein target from food: older adults with poor appetite, people in a calorie deficit trying to preserve muscle, and vegetarians who eat dairy. High protein intakes have not harmed kidney function in healthy people; people with chronic kidney disease are usually advised to limit protein.

Forms and Bioavailability

Absorption ratings are broad tiers. Head-to-head human trials rarely support a finer ranking among well-absorbed forms.

Labels column: number of labels in the Protein Powder category that list this form. A product can list more than one form, and some labels do not state a form at all.

Concentrate (usually WPC80) is about 80% protein and keeps some lactose and milk fat, typically a few grams of lactose per serving. Isolate is at least 90% protein with lactose removed to well under a gram per serving in most products. Hydrolysate is whey pre-cut into peptides; it absorbs slightly faster, tastes bitter, and costs more, without a demonstrated advantage in long-term muscle gain. All three contain the same milk proteins, so none is safe for people with a milk protein allergy, which is different from lactose intolerance.

Typical Dosing

Exercising adults are commonly advised 1.4-2.0 g of total protein per kg per day. A single serving of 20-40 g of whey provides enough leucine to maximally stimulate muscle protein synthesis in most adults.

Food sources: milk, yogurt, ricotta cheese.

What to Look For

Divide protein grams by the scoop weight. A 30 g scoop with 24 g protein is 80% protein; one with 20 g protein is carrying a lot of sweetener, flavor, or filler. A serving should provide about 2.5 g of leucine. Good brands print the full amino acid profile.

Read the ingredient list for free amino acids such as glycine, taurine, or glutamine. Protein content is often tested by nitrogen, and cheap added amino acids inflate the number without providing the same leucine; this practice is called amino spiking. "Protein matrix" or proprietary blends can hide inexpensive proteins behind whey on the label.

Protein powders have tested positive for heavy metals in independent surveys, so third-party certification (NSF Certified for Sport, Informed Choice) is worth paying for, especially for daily use.

Products on Titrate

The Protein Powder category in Titrate's index holds 5,888 labels from the NIH Dietary Supplement Label Database, 3,475 of them currently on market, out of 214,745 labels indexed in total.

Top on-market labels, ranked by label completeness and simplicity:

1. 100% Hydrolyzed Whey Protein Unflavored NutraBio · 31.6 g as hydrolyzed
2. 100% Hydrolyzed Whey Protein Unflavored NutraBio · 31.6 g as hydrolyzed
3. 100% Hydrolyzed Whey Protein Alpine Vanilla NutraBio · 31.6 g as hydrolyzed
4. 100% Hydrolyzed Whey Protein Alpine Vanilla NutraBio · 31.6 g as hydrolyzed
5. 100% Hydrolyzed Whey Protein Dutch Chocolate NutraBio · 31.6 g as hydrolyzed

Search protein powder supplements

Supplement Search loads one category at a time. Choose the Protein Powder tab, then type a form such as "hydrolyzed" under Must contain, or a form to avoid under Must not contain.

Related Tools

• Protein Intake
• Macro Calculator
• Hydrolyzed Whey Protein vs Whey Protein Concentrate
• Hydrolyzed Whey Protein vs Whey Protein Isolate
• Whey Protein Concentrate vs Whey Protein Isolate
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References

Institute of Medicine. National Academies Press, 2005. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids.

Moore DR, et al. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009;89(1):161-168.

Tang JE, et al. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009;107(3):987-992.

Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013;10(1):53.

Macnaughton LS, et al. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep. 2016;4(15):e12893.

Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.

Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384.