It depends on the person. Such things as current lean body mass, sleep/work time of day, training time. BUT, given a fairly standard lifestyle of 9 to 5 work and early morning gym time, carbs late at night get digested and stored (and we all know what the body's storage system is, I hope.) Fuel is to be burned, and if it is not burned within the window available based on the glycemic index of the carb and the standard rate of digestion (2-4 hours), it stores as fat, making it harder to access as fuel later. it depends on the type and quantity of carbs that constitute "all your carbs". If your total of carbs is half a gram per pound of bodyweight, and all green vegetable, no prob. If "all your carbs is 3 to 4 grams per pound of body weight and they are starchy or very high glycemic, fat will be inevitable!