Earlier quoted context omitted.
The issue is that doctors give you muddled advice too. I had my blood test done last year and I was told that I should cut down on eating any meat and switch to a plant based diet. He also vaguely told me to do more exercise. Yet, I eat incredibly lean food, albeit high protein mainly because I weight lift. I also run 4.5 miles every other day. He couldn't go into more detail apart from this general warning. I could…
The claim that you can't get sufficient protein for pretty much any level of exercise from a plant-based diet is utterly specious. For example, quinoa is 14% complete protein, and chia is almost 17% — also complete protein — with an Ω3-to-Ω6 ratio of around 3:1, almost exactly the inverse of beef. Source: I'm a vegetarian, and I pay scrupulous attention to this stuff.
Quinoa provides 3.8 grams of protein per 100kcal of energy [1]. Boneless skinless chicken breast provides 18.8 grams of protein per 100kcal of energy [2].
A weightlifter who wished to consume 100 grams of protein per day would have to eat 2632 kcal of quinoa, vs. 532 kcal of chicken breast.