I’ve been on Soylent for about 3 weeks, 2 of which have been mostly full time. My biggest hurdle was finding a way to keep it cold at my office all day. I didn’t want to have to walk across the office to the fridge whenever I wanted a sip.
I keep my Soylent frosty for 14 hours a day (I haven’t tested longer than this) using a 32oz Hydroflask and 8 Stainless Steel Scotch Rocks. The Scotch Rocks are basically stainless steel ice cubes with a gel inside that keeps your drinks cold without dilution. You can use them in your Soylent all week then your Johnny Walker all weekend.
When I say frosty, I mean that after 14 hours it’s the same temperature as if I pulled it out of my fridge. Touching the scotch rocks is like touching an ice cube, and if you shake it, the gel inside is not quite as “liquidy” as it is when it’s room temperature. In short, it’s still frosty after 14 hours.
I don’t find it necessary to “freeze” my Hydroflask over night either, though the Scotch Rocks do need ~7 hours for the gel inside to freeze solid.
Your experience will vary if you’re not in an A/Cd office all day, but I find even going to the beach with it I’ve never had a warm drink from my Hydroflask.
There are cheaper versions of the Scotch Rocks out there, but these are the only brand to arrive so far (I’ve ordered two more no name varieties, 3 week shipping from China). I would imagine they should all perform similarly.
Anyhow, I’d seen plenty of people asking about keeping Soylent cold all day, but I didn’t see anyone doing it this way.