Whey alone did nothing for older adults, unless they also lifted
Across 30 trials in 2,105 adults over sixty, handgrip, gait speed, walking distance and lean mass all sat across zero. Lower-body strength improved where people lifted.
What the study found
Whey missed grip strength, walking speed and lean mass in over-60s
Thirty trials and 2,105 adults over sixty, and on six of eight outcomes the confidence interval sat across zero: handgrip, gait speed, six-minute walk, timed up-and-go, lean body mass, fat mass. Lower-body strength did improve, in the trials that also had people lifting.
The caveat · Some may already have eaten enough
Baseline protein intake was not consistently controlled across the trials, so some of these people may already have been eating enough for a supplement to add nothing. The handgrip analysis was highly inconsistent between studies. Appendicular muscle mass did improve, but on two trials that disagreed sharply with each other. Older adults only, so this says nothing about young trained people.