There are several factors that come into play and cause your weight
to go up or down - from the food you eat, the fluids you
drink, the amount you sweat when exercising, etc.
I just posted a video showing a real time example of this by purposely losing 2.5 pounds
in just 90 minutes of exercise...
And then re-gaining it all back again
within another 30 minutes of eating and re-hydrating afterwards.
Now this brings up the question:
How do you accurately track your body weight if it's constantly fluctuating up and down?
How do you weigh yourself and get your "True Weight" that you can then use for tracking your progress when trying to lose weight (or gain weight) ?