Whey protein
A convenient way to top up protein when food alone falls short
What it is
A whey protein powder: concentrate, isolate or hydrolysate. The practical difference between the forms is minimal: a 30 g serving of any of them gives about 21–27 g of protein.
Benefits
Combined with resistance training, protein supplements help build muscle mass: meta-analyses confirm it, though the effect is not large (IOC). Whey digests fast and, right after intake, stimulates muscle protein synthesis more than soy or casein (ISSN).
Dose
Per serving: 20–40 g of protein, or 0.25 g per kg of body weight (ISSN); IOC gives 0.3–0.5 g/kg. AIS: no more than 40 g at once and 1–2 servings of supplement a day. Total daily protein from food and supplements: ISSN 1.4–2.0 g/kg, IOC 1.6 g/kg, AIS 1.2–1.6 g/kg.
When to take it
Exact timing matters less than your total protein for the day. ISSN suggests spreading it evenly, every 3–4 hours; it helps both before and after training. A meta-analysis found that protein within an hour before or after exercise does not by itself add strength or muscle (NIH ODS).
Who it's for
People who struggle to get enough protein from regular food, for example with a poor appetite or a high training volume. A supplement is a practical way to get quality protein without extra calories (ISSN).
Who can skip it
If food covers your protein, you don't need it: AIS notes that most athletes reach their targets without supplements. ISSN doesn't treat protein powder as a requirement for results either. It adds to regular food rather than replacing it.
Forms
Concentrate contains 70–80% protein with small amounts of carbohydrate and fat; isolate is filtered further, typically to 90% protein with minimal carbohydrate and fat; hydrolysate is protein broken down into short peptides and is the most expensive form (AIS). According to AIS, the practical difference between the forms is minimal; the small amount of lactose in concentrate may matter for people who are intolerant to it. In a 2017 trial (56 resistance-trained men, 8 weeks) strength rose equally with concentrate, hydrolysate and placebo; hydrolysate reduced fat mass and gave no other advantage. In a separate study hydrolysate restored strength faster than isolate after hard eccentric exercise (a 2010 review).
Safety
In healthy active people, higher protein intake has shown no harm to the liver or kidneys (ISSN); in kidney failure protein is restricted. No upper limit is set, but data on high intakes are limited (NIH ODS). Concentrate has a little lactose; possible allergens: milk, soy, tree nuts. We found no data for pregnancy or teenagers: see a doctor first.
Work out your numbers
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- International Society of Sports Nutrition Position Stand: protein and exercise . ISSN, 2017.
- ISSN position stand: nutrient timing . ISSN, 2017.
- ISSN exercise & sports nutrition review update: research & recommendations . ISSN, 2018.
- IOC consensus statement: dietary supplements and the high-performance athlete . IOC, 2018.
- AIS Sports Supplement Framework — Isolated Protein Supplements, Practitioner Fact Sheet . AIS, 2025.
- Dietary Supplements for Exercise and Athletic Performance — Health Professional Fact Sheet . NIH ODS, 2024.
- Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males . Journal of the American College of Nutrition, 2017.
- Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein . Nutrition & Metabolism, 2010.
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