One scoop of whey protein has over five times more of the key muscle-building amino acid (leucine) than one scoop of collagen protein—even though both have the same total protein.

Even though both protein shakes had the same amount of protein, the whey one made the key muscle-building amino acid (leucine) in the blood much higher than the collagen one.

After drinking whey protein shakes every day for a week, older women’s muscles kept building up new protein even on days they didn’t exercise—collagen protein didn’t do this at all.

Collagen peptide consumption results in improved nitrogen balance relative to whey protein in elderly populations.

When older women drink whey protein shakes, their muscles start repairing and growing faster—especially if they also do leg exercises—while collagen protein shakes don’t do much unless they exercise, and even then, it’s much weaker.

Older women around 69 years old who drink a whey protein shake every day and lift weights three times a week for three months may gain more muscle, lose belly fat, and improve their overall metabolic health more than those who just do the workouts without the protein.