Given that top body builders are vegans, I'd guess - not much
Also no one should emulate top body builder diets unless they plan on working out like top body builders (e.g. 2-3 intensive training sessions a day).
You might be able to find a few vegan body builders but its certainly not the norm.
0: http://www.businessinsider.com/the-mountain-game-of-thrones-...
And indeed there are some. Which points that there's no necessary connection between being vegan and losing muscle.
(note to self: quit trying to crack jokes on HN)
;-)
Top body builders eat meat. Top body builders do not eat meat.
The implication is "The top body builders", but yes, there's wiggle room for when someone challenges the statement.
All comment had to say is some top body builders are vegan. Even some notable NFL players are/have been vegan.
Even then, they go out of their way to get enough protein - I think the person you replied to was trying to go for shock value but it was a pretty bad comment.
I imagine that diet is irrelevant for athletic training, as long as it fulfills certain macro-nutrient requisites. Further, I image vegan athletes are only faced with the increased difficulty of finding and preparing quality sufficient food, compared to others with normative diets, due to lack of demand and meat centered cultures.
Finding an equivalent vegan alternative to chocolate pudding at <500g, 350kcal, 50g protein> for $2.5 [2] seems like a challenge. I'm sure that if they plan their diet, they can meet the same targets - whereas normative diets don't require you to plan anything really. You can just eat 2 of [2] and a chicken a day, and you're done (concerning only protein).
But then again, there are protein powders which balances it out, if we don't take price into account.
All in all, I think diet choices (assuming any choice to be a most healthy variant of chosen diet) mainly impacts long term health, and not short term goals such as muscle gains.
[1] http://www.greatveganathletes.com/strength [2] http://www.njie.se/produkt/propud-protein-pudding-chocolate/...