How to tell if you have eaten too many carbs

I cant validate this but I read that if you weigh yourself just before you go to bed and then weigh yourself as soon as you awake and you are 2lbs or more lighter then you eat too many high glycemic carbs the previous day.
2 days ago I was 11stone 4 and 11st  2.5 the next morning.Last night I was 11 st 2 and 11st 1 this morning .