If you're consuming enough calories (which, most people are), you're probably getting enough protein. Protein's in everything except fat, sugar, and fruit. Granted, if you're only eating Cheetos and drinking soda, you won't be getting much, but I suspect if Cheetos and Coke are the staples of your diet, you aren't too concerned about your protein intake anyway.
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Back to the article... the whole host/tourism thing is a little lost on me. If you're vacationing somewhere, I don't think you have ANY obligation to people selling food on the street, or really, selling food anywhere. You shouldn't be RUDE about it, but politely saying no isn't a crime. I very politely don't buy things in the US all the time
