If you want to lose a small amount of weight quickly, you should do so effectively and safely, no matter your reason for wanting to shed pounds. However, you can safely shed weight from retained water and waste, and lose 5 lbs. (2.3 kg) or more within one day. Be aware, though, that this process cannot be safely repeated for more than one day (i.e. you cannot safely lose 15 pounds in three days), and the weight that you lose in one day is likely to return quickly. It is smart to maintain a healthy body weight, and weight loss should be combined with long-term lifestyle changes, like eating healthy and exercising.