I suggest you invest in a middle range digital scale with BMI features. Something from Costco or Bed Bath & beyond. They take electrical pulses readings through the feet, and calculate percentage of body fat, percentage of water, bone mass, percentage of muscle, and eventually give you a BMI index.
I track mine daily, best to get a reading around the same time every day, morning, before breakfast, after 'dropping the kids off at the pool'
After a recent warm weather 3-day trip, I was down 10 lbs, and was quite happy, then I hopped on the scale for the reality check. the BMI score had not changed, and it was indeed mostly water loss, which I quickly regained.
The other sneaky thing to pay attention to, on the trail, the 'turtle-head' output is increased due to movement, so 'releasing all the hostages' also lowers the weight by a couple of lbs, but that is transient weight, it's not your body's true weight, and it's quickly replenished after a couple of days in the office chair.