>> We weren't made for anything.
No, but our bodies have been fine-tuned through evolution over the last million years, up until probably the last 20,000 or so. Your digestive tract is different from a cow, snake, or wolf for a reason.
Fine tuned maybe, but with the goal of "stay alive just about long enough to be useful", we're pretty awfully constructed. For example, we need ultraviolet light to not get rickets but it can also give us cancer. Our fine-tuned digestive tract contains an organ which occasionally bursts. My wisdom teeth have decided that they'd rather grow forwards than up.
Evolution gets you to functional, it doesn't get you to "good".
To suggest that what we've been doing in the past is optimal seems ridiculous to me. I'm not saying I think this gruel is a good idea, but the argument "it's not natural" holds no weight.
I don't particularly like the idea of soylent, but coming at it from a "but it's not natural" is just ridiculous. You know what's natural? Dying in horrifying ways, with no hope or understanding of what's happening. Fuck natural.
Remember natural smallpox? Not a single person in the world has it. How many people die during childbirth now compared to 150 years ago?
> a way that our body was never made for?
We weren't made for anything. We're a loosely connected series of insane reactions that just about doesn't die. We put load on non-load bearing structures (hi, spine), we have our optic nerve running through the centre of our retina giving us a blind spot, our body can decide that peanuts = a threat so bad we should stop breathing and occasionally some of our cells will rebel and try and kill us. We don't even produce vitamin C thanks to a single error, something we need to live and could easily produce.
We weren't made for anything, we just are.