The Pants

SO here is the question... What is it about losing weight that allows clothes that fit one day not fit the next? and no I am not talking about just fitting better or being a little lose I am talking about the sudden change in body shape that makes the pants you wore the day before while they may have been lose or big but they fit and stayed up become an adventure in keeping your pants up all day? Case in point the pants I am wearing today I also wore yesterday. They were big and with effort I could have pulled them off with out unbuttoning them but there was no concern that they would just fall off or stay put when I got out of a car and yet today I feel like is I am not careful I will walk right out of them. This has got to do more with body shape than with weight my weight did not change that drastically over night! But did my body shape shift or something? I know little babies and kids can go to sleep and wake up having grown losing something of their babyness or changing over the course of a nap from a new born to an infant to a toddler to a two year old in looks. So does that also happen with weight loss? do we go to sleep and our bodies shift the weight distribution around or maybe it is a matter of organs moving and settling in new spots as the fat goes away? This would explain why one day something fits ok and the next you really shouldn't be wearing it at all. All I know is it is weird.