Well, I think a 10 pound fluctuation is a bit extreme. My weight tends to stay in a 2-3 pound range throughout the day. And there will still be some fluctuation even if you weigh yourself the same time every day because there at least a million different things that can affect your weight at any given time (dehydration, retaining water, empty/full stomach, etc.) The scale is imperfect and should not be taken as gospel. More importantly, it can't tell a pound of fat from a pound of muscle from a pound of water. I use both a scale and a tape measure to let me know I'm headed in the right direction.