I’ve been on 2 Huel shakes a day (weekdays only) for around 18 months. My stomach took around 2 weeks to adjust but is now fine and regular. I’m now having v3 for breakfast and Black for lunch (following a lunchtime gym session).
I find now that if I don’t have a Huel for lunch and instead go back to my old eating habits (a Greggs’ or Sainsbury’s meal deal: sandwich, crisps, juice and a sweet treat such as a doughnut or cookie) then my stomach really doesn’t like it. I’m pretty sure it’s the wheat that my stomach doesn’t like.