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"Water Weight"

Scientists out there, please settle this curious question that I've had forever.....

If a person drinks a pound of water (or eats a pound of food, etc.), do they immediately weigh one pound more? It seems likely, until you begin thinking about the potential energy used in consuming and dealing with what's been ingested.....

Anyone know?

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  1. If you ingest a pound of food or beverage then immediately weigh yourself, you will weigh one pound more than you did before ingesting. Over time, your body will absorb nutrients, convert the calories into energy, fat, muscle, etc... then you excrete/secrete what ever your body didn't absorb. Whether or not you keep the weight gained immediately from ingestion, and how much you keep, depends on what was ingested and how your body uses it.

    1 Reply
    1. re: mpjmph

      Hence the concept of strategic "water loading" on The Biggest Loser. Not that I watch it or anything.

    2. With newborn babies who are breastfeeding and suspected of not getting enough milk, they sometimes weigh the baby before and after feeding to estimate intake. However I just googled it and it seems some studies show this method isn't all that accurate.

      1 Reply
      1. re: julesrules

        I wonder what the result would be if they weighed the mom before and after, too. Interesting. And, if a mom and baby were on a scale and the baby were nursing, would the scale stay the same?

      2. I would say that, immediately after drinking, you will. There is some energy used in consuming the food, but it's not all that much. For pure water, you'll lose most of that weight in a short time period through sweat and urine, as there is no caloric content. For food, your body will absorb some of it to either burn or store as fat, and get rid of the rest, either in the bathroom or through sweat. So there might be a small gain of weight, but not the full pound.

        You could test this pretty easily, though, with an accurate enough digital scale. Weigh yourself. Drink a pound of water. Weigh yourself again. Repeat the exercise on different days to get a good statistical sample (as you're probably pushing the accuracy of a bathroom scale).

        Calculate the different between the weights for each measurement. Then calculate the mean and standard deviation of the differences. If you measure a difference, and the standard deviation is significantly lower than that difference then you've experimentally verified it. If the difference you measure is smaller or comparable to the standard deviation, though, your scale isn't accurate enough, or you need more measurements.

        1 Reply
        1. re: tastesgoodwhatisit

          Unfortunately, my scale is not that accurate, for sure! I was hoping someone else would do my work/thinking for me! :-)

        2. I had a friend who went to one of those whiz-bang medical weight-loss clinics -- and they would urge her to go to the bathroom before she weighed in, as it was possible to *lose* a pound or more with a strategic elimination.

          8 Replies
          1. re: sunshine842

            That's something else I've sometimes thought about - privately.....! Looks like a lot of weight could....go away.....during.....that process.....HA

            1. re: sandylc

              Thankfully, she finally quit marching to the beat of that particularly crazy and malevolent drummer -- but not until after she'd dropped a lot of cash, and ended up so malnourished that she stopped menstruating and took a pretty solid chewing-out from her GP.

              Thin, but not worth it.

              1. re: sunshine842

                Another great reminder that thin, unto itself, does not equate to healthy!

            2. re: sunshine842

              It also explains how people can go on a diet and 'gain' weight. (The mystery is why people need this explained to them!) I've noticed I frequently lose 2 lbs overnight in water weight.

              Here's something I've never understood though. There was a time, years in fact, when I weighed 107 lbs. Every time I stepped on the scale, before eating, after eating, for years. Magic scale? Magic body? Even at the time I was mystified.

              1. re: foiegras

                Yeah, I was stuck on 92 until about 26-27 years old. Now, I'm...........NOT 92.

                1. re: sandylc

                  Yeah ... now I have a digital scale, and for some reason 107 hasn't popped up lately.

                  1. re: foiegras

                    107 pops up on my metric scale.

            3. Yes, when you eat a pound, you will weigh a pound more.

              If you stand on a scale with a pound of water in a cup, you will weigh 1 pound more (plus the weight of the cup). When you drink that water, your belly is now holding that pound.

              It doesn't matter if it's on the cup or in your body, it's still one pound more.

              BTW... 2 cups of water (8 fluid ounces per cup) is roughly 1 pound (weight).

              4 Replies
              1. re: dave_c

                BTW... 2 cups of water (8 fluid ounces per cup) is roughly 1 pound (weight).
                ~~~~~~~~~~
                The little rhyme I learned from Alton Brown's show helps me remember that conversion:

                "A pint's a pound the world around."

                1. re: kmcarr

                  The problem I had with that ep was he said it was British and their pints are different than ours

                  1. re: jgg13

                    Did he? I always took him to be referring to an American pint of 16 fl. oz.

                    1. re: kmcarr

                      Looks like I was wrong. I must have assumed it was british as it sounds very Old Imperial kinda sounding but the british phrase is apparently "a pint of water weighs a pound and a quarter"