This approach may work of you don't have hyperinsulinism and insulin resistance. If you do, then eating even one high carb item, even if you keep your carb intake low for the rest of the day, will provoke an insulin response and only continue the insulin resistance because with those conditions, it's not the total amount of carbs you eat in a day that matters, it's the total number carbs (and their glycemic value) that you eat at one time.