I am currently trying to lose ten lbs, and was not doing so well, until a few minutes ago I hopped on the scale, and it turns out I've lost 20. That's down significantly more than 10 lbs from when I weighed in before I worked out. I didn't workout very hard, but today was something of a fast day. I allowed myself no extra snacks, no food other than strict meals. I drank 64 oz of water. This was probably at my peak calorie burning time. How did my weight do this? I assume I will gain it back in a few days, if not already. (I ate dinner afterwards, and can feel my stomach swell.) I am only 17, so its possible that my metabolism is unsteady, although my weight generally is pretty stable.I was actually at plateau the last few weeks. I am positive it's not the scale, my parents say it works consistently for them, as does my sister.

  • What's your actual weight? It's physically impossible to lose 20 lbs in one hour. That's 2 1/2 gallons of water; you'd be dead or close.
    – Eric
    Commented Feb 25, 2016 at 5:37
  • My immediate impulse is clothing. I've never seen a twenty pound shift, but I know there's a 10 pound difference between my work clothes and my workout clothes, primarily due to a combination of shoes and stuff in my pockets.
    – Sean Duggan
    Commented Feb 25, 2016 at 17:15
  • I went from 128 to 113. This afternoon i still weigh the same. I was wearing shorts and a t-shirt both times... pretty light weight, and barefoot. Did all of my weight loss catch up with me at once? I ate nearly identically today, and have once again drank 64 oz.
    – Hollis
    Commented Feb 25, 2016 at 20:48
  • 4
    In the absence of something extraordinary happening to you, the simplest explanation is that your abnormal weight loss never existed. For one reason or another your scale gave an aberrant reading.
    – Doug B
    Commented Feb 25, 2016 at 21:00
  • It can be good idea to visit doctor, doing some blood tests. If you are worried - take some solid information, from certified sources... Other point is - it can be a problem with measurement. I would see that 15-20 lbs - in the mirror, so if that was not noticed? 1-2 lbs per month - for long term weight losing is something that has no worries according to medical point of view. Third - short time loss goes in toilet visit, sweat... Combine it all, and make your own decision. Commented Apr 26, 2016 at 14:45

1 Answer 1


As noted by the comments from @Eric Kaufman and @Sean Duggan, losing that kind of weight in an hour is likely not possible and certainly not safe. By comparison, I weight close to 220 lbs and will lost 2 lbs through persperation after one hour high-intensity exercise. I did lose close to 7 pounds once, but that was due to taking a purgative in preparation for a colonoscopy...

The weight loss that you see is therefore probably an artefact:

  • Per @Sean Duggan ensure that you are wearing the same/similar clothes at each weigh-in.
  • Regardless of the opinion of others, your scale may not be working properly. Try re-taring it. Ensure that it is level. And try a different scale.
  • I only have one scale... and see my other comments in response to your other suggestions
    – Hollis
    Commented Feb 25, 2016 at 20:49

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