Just eat regular soylent and the low glycemic index of oat powder will = weight loss (maybe, if it's low enough). Or switch to a ketogenic diet by replacing carbs with fat (more once you reach maintenance weight) and adequate protein. Heart/blood health markers all improve eating all that fat after adaptation (yup, they get better not worse), hunger goes away, and you lose weight. Aaaand that's thread.
I did low calorie soylent for a month, then made it ketogenic, and am now currently simply following a ketogenic diet (no soylent), but I did just donate to the soylent campaign. If they make a very very low glycemic index and/or low/no carb version I'll be giving that a go.
Oh and I lost about 20 pounds, am now about 10-11% body fat, started at about 15-16%. Bitchin'. From the low carb diet, not soylent. Although I lost some on low calorie soylent too but I was way way way hungrier and was actually eating way too few calories and suffering from it on occasion.