Refined sugars are always simple sugars, which spike your insulin levels more than complex carbs. I’ve heard insulin described as a “storage hormone,” which is why carbs are great for bulking.
And, if what @duketheslaya said is true, and he really wasn’t working out very hard or very long, his body probably didn’t need the carbs/couldn’t use them efficiently. Unless your blood sugar is low, which only happens after long periods of rest or long, hard workouts, you don’t need to be eating many carbs at all. If your blood sugar is at an acceptable level, and then you ingest a ton of carbs, your body is going to kick on the lipogenesis and start turning the extra carbs into fat.
The cynic in me wants to get behind the whole “a calorie is a calorie” thing, but it’s hard. There’s a lot more that goes into diet than ONLY the amount of calories you eat. If you eat 400 calories of chicken vs 400 calories of fruit snacks, your body is going to react differently. Even 400 calories of whole wheat pasta (complex carb) vs 400 calories of fruit (simple carb) can affect people differently.
To get back to the point, though, I think cutting out added sugars is a great way to control calories. That eliminates so many energy dense foods. Cutting out sugar, period, is not a good idea. That means no fruit, limited veggies, and greek yogurt that tastes like butthole. You still need to eat nutrient dense foods on a diet, which can include red/somewhat fatty meats and fruits, but an apple is objectively healthier than two scoops of ice cream (or whatever your dessert of choice is).