I have no horse in this race - but another anecdote is Tom Brady - who recently mentioned how he has a mostly vegetarian diet, except some chicken in the winter. Granted, Quarterbacks don't put on nearly the same muscle mass as other positions - in terms of overall fitness, you can't deny Tom Brady is in very good shape.

Throwing another anecdote on the pile:

I've been vegetarian for 2 years and have zero perceptible changes to weight or muscle mass (I don't take supplements either).

another anecdote here:

I went pescatarian 1.5 years ago and have put on 10-20 pounds. It's really been hard (for me) to feel full without those chicken breasts I used to make and the occasional steak. Fish simply doesn't keep as long. I end up eating lots of junk food :(

I don't think it's a bad idea. I just need to get more prepared, clever and disciplined. I actually wasn't looking to lose weight at all, just be healthier. It's been a surprise how hard it is to get back to my original weight.

Preparation is key for me. It's so easy to backpedal into junk food if you don't have a healthier alternative ready to go. There's just so much junk out there.

I do meal/snack prep on Sundays, which goes a long way. I eat less grab-and-go junk and I save money too.