For young people new to lifting weights, taking soy protein or whey protein daily seems to have the same effect on thigh muscle growth.

74

Pro

0

Against

Evidence from Studies

Supporting (1)

74

Community contributions welcome

74

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial

Randomized Controlled Trial

Human

2020 May 29

The study looked at the exact same protein supplements and exercise routine as described in the claim, and found that both groups had a small, not-quite-significant increase in leg muscle thickness, with no real difference between soy and whey.

Contradicting (0)

0

Community contributions welcome

No contradicting evidence found

Gold Standard Evidence Needed

According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.

Source Study

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial

Score: 74

DOI: 10.3390/ijerph17113871

Similar Assertions

If you're a young adult just starting strength training, drinking a shake with either whey or soy protein—both with the same amount of a key muscle-building amino acid (leucine)—will help you gain muscle equally well over 12 weeks.

74

0

88%

If young adults who aren't used to working out eat a bit more protein—especially from whey or soy—and lift weights 3 times a week for 3 months, they’ll likely gain more muscle and get stronger, even if they weren’t eating enough protein to start with.

74

0

81%

If young adults who aren't used to working out do strength training 3 times a week for 12 weeks, they’ll gain about 1.5 kg of muscle and get stronger legs — and it doesn’t matter if their protein shake is made from soy or whey, as long as both have the same amount of leucine (2 grams per day).

74

0

78%

If you're a young guy who lifts weights and already eats enough protein, taking extra leucine pills for 12 weeks won't make you stronger or build more muscle in your thighs than just lifting weights by itself.

75

0

73%

When rats ate a larger dose of regular whey protein, their blood had more leucine than when they ate the same amount of hydrolyzed whey protein an hour later.

13

0

73%