[dack]

If it's the case that there are other existing solutions that are simultaneously as {cheap, nutritious, tasty, storable} as Soylent, then the problem is marketing. I don't know about them.

If, however, the existing solutions have a major downside (I would assume cost or taste, but could be wrong), then that's the reason. I wouldn't be surprised if there were existing solutions that just aren't catering to the audience of "silicon valley hipster" and therefore simply getting ignored.

According to your link on Plumpy nut, it's only $60 for 2 months for a child. Even though a 280lb. man certainly needs much more than whatever the amount is for starving children, it still sounds like it would be cheaper than I would normally spend on food even if I just bought groceries and never ate out. So... could I eat that food for 2 months straight and be perfectly healthy (assuming I have the willpower)? Could I reasonably use it as a meal replacement whenever I wanted and not have any negative consequences?

[Pitarou]

No. Of course not. Plumpy'nut is just an example. But there are formulations for people with digestive ailments, military rations, and so on.

Alternatively, it's perfectly possible to design your own "Soylent style" diet, optimising for cost and convenience. I knew of someone (friend of a friend -- a rather eccentric math teacher) who did that many years ago. A large part of his diet was spaghetti and vitamin pills ... not so different from Soylent, really.