It's healthy compared to other fast food (especially Mexican) because they make a huge effort to use healthy ingredients. I don't know the details. It's definitely calory-heavy, but so is all Tex-Mex.
Yeah, but what makes an ingredient healthy? It used to be low-fat. Now it's low-carb. Low-sodium? I don't know, Chipotle doesn't seem to be earning any merits in any of those categories. More importantly, what does it matter if the ingredients are healthy if the whole isn't? Sourcing local and organic has its merits but I think it's misleading to say that health is one of them. It's still probably better than comparable fast food, true. But if I wanted to really think about it, I can still order meal-forming items off a Taco Bell menu that are just a couple hundred calories. With Chipotle, you're left to order a regular burrito/bowl/salad and just ask for nothing in it if you want low-cal.
I don't think chipotle claims to be healthy all the time. The reality is, you can have a perfectly "healthy" and low calorie meal at Chipotle if you want. But aside from that, yah the thing is a calorie bomb - but is a calorie bomb with some of the best ingredients $6-8 can buy. I don't think "healthy" means "skinny food" or "diet food". I think it means that food can be good for you AND taste delicious. I think I'm super defensive about Chipotle because I love it, it's a Denver original, and did I mention I love it? I like that the ingredients aren't so terrible. Example: When I go to Chipotle at lunch - I get some barbacoa bomb with white rice, cheese, sour cream, and usually have a side of chips. Is that "healthy"? no. The cheese and sour cream and super salty meat is probably not the best thing for my waist line. The lady I go to lunch with on most days, gets a bowl, light on rice, occasionally chicken, light cheese, no sour cream, and occasionally guac - I don't care who you are - that's down right healthy. A guy I regularly eat with gets the chicken salad. Chipotle is what you make it. You can make the "steve special" gut bomb, or something a lot more "healthy" - and all for around $7.