Yeah, I get that, I just don't really see the appeal of eating some ultra-processed junk that's worse than the original junk food and held together with God knows what to make it resemble something that's pretty nasty in its original form. Doesn't a bean burger satisfy the urge for a junky burger, and it's a better product?
Don't beat yourself up, it's not a religion. Perfection doesn't have to be the enemy of the good, an improvement is an improvement.
Something in meat, possibly. Meat protein itself, not really. Animal proteins contain all of the 9 essential amino acids in the human diet and are therefore a "complete protein". Plant proteins taken individually don't, so you have to have a variety of plant proteins to get the full set. Absence of an essential amino acid for a sustained period won't give you low energy or keep you awake, it will cause you to waste away and it will eventually kill you. If you don't have all the amino acids you need then you won't be able to build or repair proteins and you will literally fall apart. Skin and hair falls off, teeth fall out, muscles waste away, and that's just the bits that you can see. It would not be a nice way to go.