I agree - Junk food does not have to be branded as farang only.
Fried Chinese bread, those fried sugar coated balls with taro inside, deep fored bananas, custard filled pumpkins, custard in sugary sticky rice etc are Thai junk foods heavily consumed in Thailand.
Also fast food made to order shops make up the majority of Thai restaurants. What is the difference between greasy fried rice and a cheeseburger?
How about greasy, fatty pork on stick or banana chips? They must have the same or more fat grams than most Western fast food meals.
As for an intolerance to dairy products? Thais slurp that soured milk in those tiny bottles like its going out of style.