Huel is food and, like @fakethom points out, you wouldn’t expect a clinical trial on other meals. Huel’s formula is based on science and we regularly lab test as appropriate.
As there are only a few people who consume 100% Huel (as far as I’m aware), enroling people to consume a 100%-Huel diet isn’t easy; indeed, one of the biggest challenges is complience - how will we know they subjects aren’t nibbling on biscuits unless we confine them to a controlled environment which is just not feasible?
However, @RebeccaOfficialHuel is just getting together a bunch of 100%ers for a trial which will involve blood tests, anthropometry and questionnaires. I don’t want to give more details at this point as we’re still discussing what we want. Our aim is for us to have some data by Christmas. Although we don’t need information like this, it is incredibly interesting for us and also for keen Huelers like yourself who raise fair questions like this topic.