In my opinion, Dr. Berry is the real deal, Berg is a quack chiropractor and snake oil salesman and DeLauer is pretty interesting but it irritates me when he has fake doctors in his vids. But, that’s just me and I have an aversion to chiropractors, whom I generally consider to be frauds.
On the other hand, I have no medical training at all, I’ve learned a ton and converted my own M.D. to low carb, even though he must be careful because it’s outside the standard of care. So, I suppose, even a chiropractor could, possibly, learn that not all illness and disease are caused by “subluxations” of the spine. The added issue with Berg, though, is that, unlike someone like Dr. Berry, who really wants to help real people, Berg is just selling over priced supplements and programs that serve no real purpose other than to make him rich and 50% of what he teaches is wrong.