These can be smoothies, bars, drinks, supplements, etc.
Is there something specific you look for (ex. price, ingredients, specific nutrients etc.)?
Is there a brand you like / avoid (ex. soylent, huel, hol food, etc.)
Edit:
I definitely don’t recommend fully replacing your diet with them. I know some people use them instead of other processed food / fast food / skipping meals entirely, and that’s the use case I had in mind for myself
While I think in theory it’s possible for them to work–and they might indeed work for specific people with specific needs–a percentage of people using them are probably of a similar type to others who have gravitated towards food fads through the past century.
Like, if you hit up the Wikpedia or some history site and look at food/diet ads from 100 years ago, those products look pretty ridiculous to modern eyes. But they’re marketing the same thing, right? Health? Convenience? They’re targeting people who are desperate for solutions to their problems, using marketing language common to that era.
And I think a large percentage of these meal replacement products are doing the same thing to modern people, that all the “health food” stuff from decades prior did to our grandparents and great-grandparents. People are, after all, people, and it’s easy to fall for marketing regardless of what era you live in.
That’s the thing, fad diets aren’t bad by definition. As long as you’re getting all your nutrients, it’s fine, and you’re unlikely to get malnutrition from replacing your breakfast with a shake, or a guava, or a steak.
If it helps you eat fewer calories, and doesn’t overly hurt your micronutrients, it works.