Doing "cleanses" is a popular practice, which usually means temporarily purging certain foods from your diet and taking some kind of supplement (often a juice or shake) to help your body release toxins. I think afterwards many people just go back to the way they were eating/drinking before, but if you want to take better care of your body long-term, you slowly reintroduce the foods you eliminated. If something gives you problems, you know your body can't handle that food or beverage. For instance, if you notice that dairy products make you bloat or alcohol ruins your sleep, it'll be a good idea to stay away from those.
After nine months of avoiding sugar, grains, dairy and caffeine, I notice that wheat and dairy affect me the worst. When I indulge in those, my stomach is NOT happy. If I keep it up over a period of days (think my birthday weekend), my clothes start fitting tighter. So chances are that those are two things I'll have to limit from now until I die. The dairy I can live without and not feel deprived, but wheat is still hard for me to give up. Every few weeks I come back to it because I just can't resist a dinner roll or I want to eat a burger with both buns, but it really doesn't do anything good for me. It's upsetting to think my body's sensitivity to wheat and sugar is the result of decades of abusing my pancreas with a very high-sugar and high-starch diet, but that's probably the case. Now I just have to live with the results.
Do I want to enjoy the typical American diet and feel like a normal American? Or do I want to go against the grain and feel good? For now, I'm sticking with feeling good. We'll see how far I get.