This doesn’t pass a basic sniff test. We mostly don’t eat food to replace our physical form. We mostly eat food to fuel the processes of our physical form. Big difference. Like trying to put steel, rubber, and plastic into a car’s gas tank.
You can healthily live for years just consuming cow parts (see "carnivore diet" — it works for most).
If one just eat potatoes or some other single plant, most are likely to lose their health in the long run.