I personally don't eat meat, but its not for any of the fad/trendy reasons that are aired now days.
I ate meat for years, and I kind of stopped eating it by accident - meaning that I was diagnosed with an autoimmune condition back in 2011 and went through periods of eliminating various things from my diet to find out what was triggering certain flareups. I wound up having a very severe non-celiac autoimmune allergy to gluten. It had come on all of a sudden and now I have to be super careful to avoid cross contamination with it. I'm so allergic that for example, I took a youth group to Kings Dominion and one of the kids had eaten a pop tart and they got nervous in the crowd and held my hand, and it was hot and I wiped sweat off my mouth. As soon as I did it, I thought 'ah, dang' and sure enough, it triggered a flareup.
One day, I ordered a pizza with pepperoni on it and it made me super sick. It surprised me and then I realized that it had probably been 6 months or so since I'd ate meat because everything I ate meat with had gluten in it, so I had accidentally stopped eating meat when trying to first eliminate gluten - which was much harder back then because that was before all the good gluten free options were available like now days. So then, every time I tried to eat meat, it would make me sick at the stomach so I just stopped trying.
I don't do complete avoidance, like I'll take a gelatin capsule for example. And I do consume a lot of dairy, eat eggs, and I drink a lot of protein shakes, probably more than anyone else on here - because I do do a very high protein intake and have to accomplish it without eating meat.
There are people that have always ate meat that eliminate it and feel better, but there are also people that have been vegetarians that start eating meat and feel better. I think a lot of it comes down to which method works best for you and makes you feel better as an individual.
A big problem that people that don't eat meat encounter is not getting in enough protein total. I think that is responsible for a lot of the problems that are blamed on not eating meat, that its not so much that its the not eating meat, its the not consuming enough protein.
A couple of important observations as related to your post though:
- A week wouldn't be enough time to really see how you adjust to it and if it would make you feel better.
- Some of the athletes that you mentioned that said they exceeded their prior performance goals, it may not be specifically that eliminating meat helped them reach those goals - its that after years of the same thing, a change may have stimulated new progress.
- IF you do decide to do that type of diet as an experiment, I personally would use a very good high quality whey protein isolate and a lot of it. I know the piece that you're talking about says to eliminate dairy too - but I wouldn't personally. If you eliminate more than one thing at a time, you don't know what's helping or not. For example, if you do feel a ton better, you may have felt better eliminating meat, but may have felt even better if had kept dairy. I hope that makes sense.
Plant proteins - I do not like the taste of hardly any plant proteins, but if you are going to switch to plant protein for your trial, I would strongly suggest Ketogenics IsoPlant and/or Body Nutrition PlentiPlants as they are both high quality and great tasting to be plant proteins.
I hope my post and information helps. I think its the first time I've detailed on here that I don't eat meat anymore - I normally keep it to myself because its a very unpopular take on here haha.