When is it no longer water weight?

chunkadoo

Is there a certain point at which weight loss cannot be accounted for by fluctuations in water weight? If so...around where would that milestone be?

I'm reading a lot of things about weight loss vs. body fat loss, is there a way to tell what you're losing fat without the fat pinching device? I know a tape measure would work but my stomach fluctuates a LOT so I'm not sure if that'd be the most accurate.