Snacking is a path to obesity
You’re not wrong. Eating just 500 extra calories a day (which is like two donuts, something I could pop down without even realizing I’d done it) means you’ll put on a pound a week (3500 calories = 1 pound of body fat) or 52 pounds in one year, which would take a 6’0" 180-pound man into obese territory, per BMI calculations. And TBF that’s pretty weak sauce; on numerous occasions I’ve added that much fat just over the Winter.