I just read this article: Stampede bastion of deep-fried everything faces invasion by healthy alternatives and thought it a great example of how you can’t always trust health claims. I agree with the dietiian and blogger quoted. Calling these items “healthy” is misleading and unfortunately the public has to make the informed decisons (and are not always provided with valid information.)
I think that most visitors do no expect to go to the Stampede (or a similar event) and be able to stick to ‘diet plan’. However you can make minimize the damage by deciding what food item(s) you will eat and setting a limit about how many you consume. Choose your favorite and leave the rest! It will be good for you health, your waistline and your wallet!