You are eating useless calories, no nutritional benefit, full of carbs, sugar, chemicals, flavourings. It isn't real food, it's taxing on your body to ask it to break down that much crap every day.
You'll soon get nutrient deficiencies eating like that, you'll generally feel sh*tty, tired, can't focus, can't sleep, prone to illness due to weak immune system. Getting fat is the least of your concerns.