Under a nutritionist's care, my friend did an elimination diet.
After a month, she has lost a lot of weight, and she no longer has her former all-over-body-pain which was almost disabling.
She found out that there are many foods that she shouldn't eat and now, if she does eat even a bite, she can feel the negative result.
I had the same experience. Two years ago I went to a natural alternatives lady who uses the Asyra method to see what is really going on in my body and it turned out that I have been allergic to dairy my entire life. I was always in and out of GI doctors offices without any relief whatsoever, just this drug and that procedure to lead me to just feeling like crap 24/7. After I eliminated dairy I felt like a million bucks and now I can’t even eat a little without vomiting. She also makes me go grain and gluten free for periods of time to give my intestines a chance to heal. GAME CHANGER. Our food supply is so toxic!
I know exactly what you mean by dairy tasting like vomit, because a few yrs after I'd removed all dairy products from my diet I had accidentally picked up the wrong coffee and it tasted just like sick. it's been over 20yrs now for me, without consuming any animal products at all (I'd been a vegetarian since 1974), for Ethical reason first and foremost though, the Better Health part is certainly an added benefit.