Yeah, I can't guarantee they are better than fast food. But, I bet you can find one that is similar to Soylent. It is more convenient than fast food.
I actually kinda like the McDonald's salads. I mean, as far as you can like fast food at all. If you go easy on the dressing, (the dressing comes in a package that looks like a giant-size katsup packet, so you get to decide how much you eat.) I think it's probably pretty healthy, I mean, at least when you compare to shakes.
I have used meal-replacement shakes in the past as supplemental breakfast; I like to load up on calories in the morning, but eating can be... hard before my system wakes up, so the meal-replacement shakes (with as much breakfast as I can choke down) is a reasonable way to consume as many calories as I can in the morning.
Of course, for me? meal-replacement shakes have never quelled hunger like real food, so I'm no longer using them just because I'm trying to reduce the number of calories I consume. If I eat something, it had better make me feel not hungry for a good long time. I'm having the best luck with meat and vegetables... the carbohydrates tend to make me hungry shortly afterwards. On the other hand, I have not lost significant weight. (I vary from 200 to 195#, and that has been true for some time now. As far as I can tell, most of that 5# is either water gain or loss, or inaccuracy of my cheap bathroom scale.) so "you shall know him by his fruits" - don't take my advice on losing weight, as I've not managed to do so myself.
Also, a big, sarcastic thanks. after that 'meal replacement shake' query on google, now just about every webpage I load is trying to sell me some sort of 'optimized nutrition' (Google seems to get that I'm male-identified and thus is trying to sell me the shakes targeted at 'building lean muscle' - you know, the stuff with the rippling abs on the can. Google does not seem to be smart enough to notice that I quite often google things I don't intend to buy. Really, books on what I'm searching for are usually more appropriate than products I'm searching for. Not that I often buy books through ads... but it's more likely than me buying nutrition shakes targeted at bodybuilders.)