Does whey protein help older adults build muscle?

Not on its own. A 2024 meta-analysis of randomized trials in people aged 60 and over pooled lean body mass from 11 trials and found a standardized difference of 0.02 (95% CI -0.13 to 0.17), which is no effect. Grip strength and walking tests did not change either. Whey added a small amount of leg strength only when people also did resistance exercise. For older adults already diagnosed with sarcopenia, the reviews disagree.

Myth. A whey shake does not build muscle in a healthy older person who does not train. In a 24-week trial of 128 healthy adults aged 65 and over, whey that raised total protein from about 0.85 to 1.5 g per kg of body weight a day changed neither muscle power, physical performance nor muscle mass against placebo.

Established. With resistance exercise, whey adds a little. In 11 trials that combined the two, lower body strength rose by a standardized difference of 0.25 (95% CI 0.05 to 0.45), which is small.

What the trials found

Older adults in general

The 2024 meta-analysis covered older adults in general, with or without training. Besides lean body mass, it found no effect on grip strength (0.18, 95% CI -0.13 to 0.49), the six-minute walk, gait speed, the timed up-and-go test or fat mass. A 2023 meta-analysis reached the same place for healthy older people, where whey had no positive effect on lean mass or function.

A 2025 meta-analysis of 150 trials gives the size in kilograms, though it covered adults of all ages and not older people separately. Milk protein supplements, whey included, added 0.9 lb (0.41 kg) of lean body mass (95% CI 0.19 to 0.62) and 1.5 lb (0.67 kg) of fat-free mass (0.40 to 0.94). The abstract gives no separate number for older adults.

With resistance training

A 2024 network meta-analysis of 78 trials in untrained middle-aged and older adults compared six protein sources added to resistance training. Whey ranked first for muscle mass, with a standardized difference of 1.29 (95% CI 0.96 to 1.62), and for grip strength and walking speed. These are large numbers built partly on indirect comparisons, and the abstract gives no rating of certainty. A 2022 meta-analysis of women aged 55 and over found whey raised leg lean mass only alongside resistance training. Without training it had no significant benefit on muscle strength or lean mass.

Sometimes the training did all of the work. In 39 older adults with type 2 diabetes doing resistance training for 12 weeks, strength rose in both groups and whey did no better than placebo.

In people with sarcopenia

Unsettled. Three meta-analyses of older adults with sarcopenia point in different directions, because each picked a different set of trials. One from 2024, 10 trials in 1154 patients, found whey raised the appendicular muscle mass index by a standardized 0.47 (95% CI 0.23 to 0.71) and gait speed by 1.13 (0.82 to 1.44). Some of its products were fortified blends rather than pure whey. Another from 2023 concluded that whey did not improve any of the sarcopenia measures it tested. A third, of whey added to resistance training, found effects too small to pass the minimally important clinical difference, on low to very low certainty evidence.

A 2023 meta-analysis that pooled both groups found whey improved lean mass and function in sarcopenic or frail older adults, and its authors attribute part of that to correcting low vitamin D, since some products contained it. The same mix applies to a 10-week blinded trial in 45 Korean adults aged 65 and over. There, 38 g a day of fermented whey raised the skeletal muscle mass index by 1.5 more than placebo, but the product also carried vitamin D, calcium and magnesium.

Who should be careful

Not for everyone. If you have chronic kidney disease, extra protein runs the opposite way to the evidence for limiting it. A 2018 meta-analysis of 19 trials in 2492 patients found a low-protein diet lowered the odds of kidney failure (odds ratio 0.59, 95% CI 0.41 to 0.85). The PROT-AGE expert group makes older people with an estimated GFR below 30 who are not on dialysis an exception to its higher-protein advice. A protein powder is a question for your kidney doctor.

For people with healthy kidneys, a 2018 meta-analysis of 28 trials in 1358 adults found that higher-protein diets of at least 1.5 g per kg or 100 g a day did not change kidney filtration over time (standardized difference 0.11, 95% CI -0.05 to 0.27). Most of those trials were short. In the diabetes trial above, blood urea came out slightly higher with whey, still within normal limits.

Whey comes from milk. We found no trial data in older adults on lactose intolerance or milk protein allergy with whey, so we have no card to give on either.

What expert bodies say

The PROT-AGE study group, an international expert panel, recommends that people over 65 get at least 1.0 to 1.2 g of protein per kg of body weight a day to keep lean mass and function. That is total protein from food, not advice to take whey, and the group considers the evidence on protein type and timing insufficient. It recommends at least 1.2 g with exercise and 1.2 to 1.5 g with acute or chronic disease, with the kidney exception above.

How we searched

What would change this answer

• A large trial in older adults with diagnosed sarcopenia comparing pure whey with an equal-calorie placebo, with and without training, and without added vitamin D. We found none under way.
• A meta-analysis that explains why the sarcopenia reviews disagree, trial by trial.

More on whey itself is on the whey page.

Sources

1. ev-wpom-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 2105
   The meta-analysis of 26 RCTs showed no significant positive effect of WPS on HS (n = 11, SMD: 0.18; 95% CI: -0.13, 0.49; I2 = 69%), 6MWT (n = 5, SMD: -0.08; 95%CI: -0.31, 0.16; I2 = 0%), GS test (n = 4, SMD: -0.08; 95%CI: -0.43, 0.28; I2 = 36%), TUG test (n = 9, SMD: 0.0, 95% CI -0.15, 0.14; I2 = 0%), LBM (n = 11, SMD: 0.02; 95%CI: -0.13, 0.17; I2 = 0%), FM (n = 15, SMD: -0.04; 95%CI: -0.18, 0.10; I2 = 0%).
   
   Who: adults aged 60 and older in RCTs of whey protein supplement versus placebo, with or without training
   Effect: lean body mass SMD 0.02 (95% CI -0.13 to 0.17); handgrip SMD 0.18 (-0.13 to 0.49); gait speed SMD -0.08 (-0.43 to 0.28); appendicular muscle mass SMD 0.39 (0.28 to 0.51) from only 2 studies
   Certainty: The widest sample of older people in general, not only sarcopenic; the positive for ASM is from only two studies.
   Clin Nutr, 2024 · checked 2026-10-07 · we read the abstract
2. ev-wpom-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs, subgroup with resistance exercise · n = 11 trials
   In interventions incorporating RE, statistically significant positive effects of WPS on lower body strength were observed (n = 11, SMD: 0.25; 95%CI: 0.05, 0.45; I2 = 0%).
   
   Who: older adults in 11 RCTs combining whey protein with resistance exercise
   Effect: lower body strength SMD 0.25 (95% CI 0.05 to 0.45), I2 0%
   Certainty: Small effect; without training there is no benefit for strength.
   Clin Nutr, 2024 · checked 2026-10-07 · we read the abstract
3. ev-wpom-03 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs, PROSPERO CRD42023407885 · n = 1154
   In WP group versus (vs.) Isocaloric placebo (PLA)/Routine consultation (RC) group, WP significantly increased the appendicular skeletal muscle mass index (SMD: 0.47, 95%CI: 0.23, 0.71), appendicular skeletal muscle mass (SMD: 0.28, 95%CI: 0.11, 0.45) and gait speed (SMD: 1.13, 95%CI: 0.82, 1.44) in older patients with sarcopenia.
   
   Who: older patients from community or hospital diagnosed with sarcopenia by EWGSOP or AWGS criteria
   Effect: appendicular skeletal muscle mass index SMD 0.47 (95% CI 0.23 to 0.71); appendicular skeletal muscle mass SMD 0.28 (0.11 to 0.45); gait speed SMD 1.13 (0.82 to 1.44)
   Certainty: Only people with diagnosed sarcopenia; some of the products are fortified blends, not pure whey.
   J Nutr Health Aging, 2024 · checked 2026-10-07 · we read the abstract
4. ev-wpom-04 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = —
   Whey protein supplementation improved LM and function in sarcopenic/frail older adults but had no positive effect in healthy older persons.
   
   Who: healthy and sarcopenic or frail older adults in RCTs of whey protein with or without vitamin D
   Effect: no effect on lean mass or strength overall; in sarcopenic or frail adults lean mass SMD 0.982 (95% CI 0.228 to 1.736, 11 comparisons)
   Certainty: Large SMD with a wide CI; part of the effect, according to the authors, comes from correcting vitamin D deficiency.
   Adv Nutr, 2023 · checked 2026-10-07 · we read the abstract
5. ev-wpom-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized clinical trials, GRADE · n = 591
   However, the effect sizes were small, and the MD did not exceed the minimally important clinical difference.
   
   Who: sarcopenic adults aged 60 or older doing resistance exercise training with whey protein versus training with or without placebo
   Effect: appendicular muscle index SMD 0.24 (95% CI 0.05 to 0.42); handgrip +5.1 lb (0.02 to 10; metric: 2.31 kg, 0.01 to 4.6), below the minimally important clinical difference
   Certainty: GRADE low/very low; only 5 RCTs in the quantitative synthesis.
   Nutrients, 2023 · checked 2026-10-07 · we read the abstract
6. ev-wpom-06 · Meta-analysis or systematic review · systematic review and frequentist network meta-analysis of RCTs · n = 5272
   Among the six protein sources identified in this NMA, namely whey, milk, casein, meat, soy, and peanut, whey supplement yielded the most effective treatments augmenting efficacy of RT on muscle mass (SMD = 1.29, 95% CI: 0.96, 1.62; SUCRA = 0.86), handgrip strength (SMD = 1.46, 95% CI: 0.92, 2.00; SUCRA = 0.85), and walking speed (SMD = 0.73, 95% CI: 0.39, 1.07; SUCRA = 0.84).
   
   Who: untrained community-dwelling, hospitalized or institutionalised middle-aged and older adults doing resistance training
   Effect: whey plus resistance training muscle mass SMD 1.29 (95% CI 0.96 to 1.62), SUCRA 0.86; handgrip SMD 1.46 (0.92 to 2.00)
   Certainty: Large SMDs and indirect comparisons; no certainty rating in the abstract.
   Nutrients, 2024 · checked 2026-10-07 · we read the abstract
7. ev-wpom-07 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 10 studies
   The present meta-analysis demonstrated overall that whey supplementation does not improve any of the tested sarcopenia-linked parameters.
   
   Who: elderly people with sarcopenia in RCTs of whey protein supplementation
   Effect: no improvement in any sarcopenia-linked parameter overall; study duration and age modified handgrip and chair-stand results
   Certainty: Contradicts card 03 (different selection of studies); we record the meta-analysis divergence as axis 9.
   Nutrients, 2023 · checked 2026-10-07 · we read the abstract
8. ev-wpom-08 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs with subgroup analysis · n = 10 studies
   Without RT, WP has no significant benefit on muscle strength or lean mass.
   
   Who: postmenopausal women aged 55 and above in RCTs of whey protein with or without resistance training
   Effect: with resistance training lower-limb lean mass SMD 1.103 (95% CI 0.632 to 1.574); without training no significant effect on strength or lean mass
   Certainty: Small studies; without training, whey even reduced total dietary protein intake.
   Nutrients, 2022 · checked 2026-10-07 · we read the abstract
9. ev-wpom-09 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of RCTs · n = 150 trials
   MP supplementation substantially increased lean body mass (LBM) (weighted mean difference (WMD): 0.41 kg; 95% CI: 0.19, 0.62; p < 0.001) and fat-free mass (FFM) (WMD: 0.67 kg; 95% CI: 0.40, 0.94; p < 0.001).
   
   Who: adults in 150 RCTs of milk protein, casein or whey supplementation
   Effect: lean body mass WMD 0.9 lb (95% CI 0.42 to 1.4; metric: 0.41 kg, 0.19 to 0.62); fat-free mass 1.5 lb (0.88 to 2.1; metric: 0.67 kg, 0.40 to 0.94); no considerable effect on muscle mass
   Certainty: Not only older people; the number for older people separately is not in the abstract.
   Nutrients, 2025 · checked 2026-10-07 · we read the abstract
10. ev-wpom-10 · Randomized controlled trial(s) · randomized 2 x 2 factorial placebo-controlled trial · n = 128
    No group differences were noted in physical performance or muscle mass.
    
    Who: healthy free-living adults aged 65 or older, mean age 74, baseline protein intake 0.85 g/kg/d, in a 2 x 2 factorial trial of whey protein and potassium bicarbonate
    Effect: leg press power difference 4.7 W (95% CI -21.1 to 30.5) versus placebo; no group differences in physical performance or muscle mass; IGF-1 +14.2 ng/mL
    Certainty: No training; muscle mass measured both by DXA and by D3-creatine.
    Am J Clin Nutr, 2026 · checked 2026-10-07 · we read the abstract
11. ev-wpom-11 · Randomized controlled trial(s) · randomized blinded placebo-controlled trial · n = 45
    Compared with controls, the intervention group showed greater gains in skeletal muscle mass index (Δ = 1.5, P = .004) and eSPPB scores (Δ = 1.4, P = .017).
    
    Who: community-dwelling Korean adults aged 65 and older, BMI 18.5-30, given 38 g/day lactic acid bacteria-fermented whey protein (n=22) or dextrin placebo (n=23)
    Effect: skeletal muscle mass index gain greater by 1.5 (P = .004); eSPPB +1.4 (P = .017)
    Certainty: Small, short; the product is fortified with vitamin D, calcium and magnesium, so the effect is not only from protein.
    J Med Food, 2026 · checked 2026-10-07 · we read the abstract
12. ev-wpom-12 · Randomized controlled trial(s) · double-blind placebo-controlled randomized trial · n = 39
    WP supplementation slightly increased blood urea compared with the placebo group (p = .05), but values remained within normal limits.
    
    Who: older adults with non-insulin-dependent type 2 diabetes in resistance training, 33 g whey twice a week (n=19) or placebo (n=20)
    Effect: strength gains in both groups, whey not superior; blood urea slightly higher with whey (p = .05) but within normal limits
    Certainty: Small sample; the authors call for determining a safe dose that does not harm the kidneys in diabetes.
    J Aging Phys Act, 2025 · checked 2026-10-07 · we read the abstract
13. ev-wpom-13 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 1358
    The change in GFR did not differ between interventions (SMD: 0.11; 95% CI: -0.05, 0.27; P = 0.16).
    
    Who: adults without kidney disease in RCTs comparing higher protein (at least 1.5 g/kg or 100 g/day) with normal or lower protein intake
    Effect: change in GFR SMD 0.11 (95% CI -0.05 to 0.27), not different between diets
    Certainty: Only people without kidney disease; most studies are short.
    J Nutr, 2018 · checked 2026-10-07 · we read the abstract
14. ev-wpom-14 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 2492
    A low protein diet reduced the risk of kidney failure (odds ratio (OR) = 0.59, 95% CI: 0.41 to 0.85) and end-stage renal disease (ESRD) (OR = 0.64, 95% CI: 0.43 to 0.96)
    
    Who: adults with chronic kidney disease in RCTs comparing protein intake levels for at least 24 weeks
    Effect: kidney failure OR 0.59 (95% CI 0.41 to 0.85); end-stage renal disease OR 0.64 (0.43 to 0.96)
    Certainty: For older people with CKD, an extra 20-40 g of protein per day from powder is a direct contradiction of the prescribed restriction; decision with a nephrologist.
    PLoS One, 2018 · checked 2026-10-07 · we read the abstract
15. ev-wpom-15 · Position of an expert body · position paper of an international expert group (EUGMS with other societies) · n = —
    To help older people (>65 years) maintain and regain lean body mass and function, the PROT-AGE study group recommends average daily intake at least in the range of 1.0 to 1.2 g protein per kilogram of body weight per day.
    
    Who: older people over 65 years
    Effect: at least 1.0-1.2 g/kg/day; at least 1.2 g/kg/day if exercising; 1.2-1.5 g/kg/day with acute or chronic disease
    Certainty: A norm for total dietary protein, not a recommendation for whey specifically; the authors consider quality and timing insufficiently established.
    J Am Med Dir Assoc, 2013 · checked 2026-10-07 · we read the abstract
16. ev-wpom-16 · Position of an expert body · position paper of an international expert group · n = —
    Older people with severe kidney disease (ie, estimated GFR <30 mL/min/1.73 m(2)), but who are not on dialysis, are an exception to this rule; these individuals may need to limit protein intake.
    
    Who: older people with estimated GFR below 30 mL/min/1.73 m2 not on dialysis
    Effect: exception to the higher-protein advice; protein intake may need to be limited
    Certainty: Expert position; gives no specific limit for protein powder.
    J Am Med Dir Assoc, 2013 · checked 2026-10-07 · we read the abstract