It's not true that by weight chicken breast has higher concentration of protein than beans.
100g of raw beans, or 100g of raw lentils, has more grams of protein than a chicken breast. 100g of raw soybeans has more grams of protein than same amount of beef.
Of course, "raw" is the catch word, because when cooked, beans/lentils fill with water and then you might claim that concentration has been lowered but the amount of protein stays the same (nothing is lost by cooking).
I'm a greybeard so I've had lots of time to try different diet+exercise programs. I was a serious cyclist for a couple decades and during that time, I tied high carb, vegetarian and the 40/30/30 diet that was trendy back in the 90s. Despite being much younger and burning a large # of calories, I still had persistent belly fat, which I attribute to the large # of carbs I inhaled on the bike. 40/30/30 worked better all around though. When I started lifting I went to .8grams of protein per LB of bodyweight and haven't felt the need to try anything else.
100g of raw beans, or 100g of raw lentils, has more grams of protein than a chicken breast. 100g of raw soybeans has more grams of protein than same amount of beef.
Of course, "raw" is the catch word, because when cooked, beans/lentils fill with water and then you might claim that concentration has been lowered but the amount of protein stays the same (nothing is lost by cooking).