text: is it normal to lose 4 lbs in one day and then gain it back the next? ive made a commitment to eat healthy and exercise. and ive been doing a really good job for about a month now and have lost 12 lbs. but the past few days ive been gaining and then loseing about 4 lbs a day. is this normal? i havent changed anything and ive been sticking to my routine. totally normal! you're body is 75% water. time of day when you weigh yourself and how much you've had 2 eat/drink in a day changes your weight. also if you're about to have your period your weight will go up.