I think we need to first know more. Maybe you posted that elsewhere.
If you are not 5 lbs overweight, you won't lose five lbs.
If your 20 or more pounds overweight, then 5 lbs shouldn't take long at all. But it can come back easily because some of the weight you lose in the first few days is the food in your digestive tract and some is water weight. Some or all of this will return. You need to go at least 5 lbs beyond this point.