How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Whey protein
A powdered milk protein. With weight training, it provides a little more lean mass and strength, especially under 40 years of age, but no more than a plant protein with an equal amount of leucine.
Benefits
- With weight training, a little more lean mass, less fat mass, and more strength than with a placebo in healthy individuals under 40 years of age (meta-analysis of 21 trials)
- Combined with weight training, supplementary protein increases muscle strength and size; beyond about 1.6 g of protein per kilo per day, no further lean mass gain (meta-analysis)
- In elderly people with sarcopenia, more muscle mass and faster walking (10 trials, 1,154 participants); with weight training, better grip strength
- After an intense weight training session, strength returns a little faster, with small to moderate effects over 24 to 96 hours (13 trials)
- Taken before a meal, it lowers the subsequent blood sugar peak, especially in case of type 2 diabetes (16 trials)
- Contains 43% essential amino acids, more than most powdered plant proteins
Precautions
Milk protein allergy: to be avoided. A systematic review of side effects mostly links excessive and prolonged consumption, without supervision, to kidney and liver damage, acne, and changes in the microbiota. Dietary supplement, does not replace a balanced diet. Limitations: with equal leucine, soy produced the same muscle and strength gains in 12 weeks, and 24 g of rice protein per day did so in 8 weeks as well. In young men who were already eating a lot of protein, whey added nothing to the placebo. After 60 years of age, the largest meta-analysis (30 studies, 2,105 participants) only sees an effect on lower body strength with weight training: nothing on grip strength, physical performance, or body composition.
Recommended dosage
1.4 to 2.0 g of protein per kilo per day from all sources combined (ISSN position), in servings of 20 to 40 g.
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How to take it
- Per serving: 20 to 40 g, to be distributed throughout the day, according to the International Society of Sports Nutrition position.
- Over the day: what matters is the total amount of protein from all sources combined. Beyond about 1.6 g per kilo of body weight per day, the meta-analysis no longer sees any gain in lean mass.
- If you already eat a lot of protein: in an 8-week trial in young men, whey taken after each session added nothing to the placebo.
- Whey or plant protein: with equal leucine, soy produced the same gains in 12 weeks; 24 g of rice protein per day did too, in 8 weeks.
- Around training: after a weight training session, hydrolyzed whey stimulated muscle protein synthesis more than soy and casein.
- With age: the effect of supplementation decreases. In elderly people, enriching with leucine can restart the muscle response.
Did you know?
In young men already eating a high-protein diet, eight weeks of whey protein after every resistance training session did not lead to greater gains in fat-free mass or strength than a protein-free placebo beverage.
What the studies say
This meta-analysis, based on 30 studies and 2105 participants aged 60 and older, examined the efficacy of whey protein supplementation on muscle strength and physical performance in the elderly. Whey protein, when combined with resistance training, showed an improvement in lower body strength. However, it had no significant effect on handgrip strength, overall physical performance, or body composition.
Al-Rawhani AH, Adznam SN, Abu Zaid Z, Md Yusop NB, M Sallehuddin H, Alshawsh MA. — Clinical nutrition (Edinburgh, Scotland) (2024) — View the source study
Pairs well with
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more