I am under the impression (from dietary websites) that when excess serum glucose is stored as glycogen, body weight is increased and the reverse: when glycogen is converted to serum glucose, body weight is reduced.

I also understand that the glycosidic bond formation in glycogenesis is a condensation reaction, releasing water, whereas the rupturing of these bonds in glycogenolysis is a hydrolysis reaction absorbing water.

Please help me here: how does the body gain weight by releasing water and lose weight by absorbing water. What am I not understanding?

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    $\begingroup$ shat happens to the sugar in blood stream? $\endgroup$ – Oct18 is day of silence on SE Oct 15 '18 at 15:12
  • $\begingroup$ Where I say ‘serum glucose’ I really mean ‘blood glucose’. Apologies. $\endgroup$ – adlibber Oct 15 '18 at 16:07
  • $\begingroup$ sure, whatever. My point, if you answer my question, you'll be able to get more intuition into your question $\endgroup$ – Oct18 is day of silence on SE Oct 15 '18 at 17:50
  • $\begingroup$ You ask about what happens to sugar in the bloodstream, I presume you mean glucose in the bloodstream and, if you don't know the answer to your own question, I don't think you're going to be able to help me. Sorry! $\endgroup$ – adlibber Oct 16 '18 at 9:15
  • $\begingroup$ i am trying to give you a hint. If you can answer what happens to glucose in blood stream, you might be able to understand how weight loss works $\endgroup$ – Oct18 is day of silence on SE Oct 16 '18 at 17:04

The answer to my question is that the glycogen molecule is extremely hydrophilic. For every gram of glycogen the molecule attracts 3 grams of water. When the glycogen is hydrolysed the attached water is excreted either directly in the liver or through cellular ATP processes.


I think your trouble comes from incomplete understanding of glucose life in the human body. Basically, you need to look at Citric Acid Cycle or TCA, that works with Acetyl-CoA as starting compound.

The reaction can be condensed into:

Products of the first turn of the cycle are one GTP (or ATP), three NADH, one QH2and two CO2

The weight loss that you are interested in, comes from basically releasing CO2 into the air. As far as I understand, you breath your weight away! Interestingly, trees are going to use that CO2 later to build their tissues up.

The water doesn't play central role in process of weight loss, as body tries very hard to regulate amount of water inside the cell and in the intracellular space.

  • $\begingroup$ I have an answer to my problem and it is thanks to Khan Academy. Of course it is SO SIMPLE! $\endgroup$ – adlibber Oct 17 '18 at 16:52
  • $\begingroup$ your source is undoubtably correct regarding fat burning aaaaa, not only carbon dioxide of course but also water are the end products of cellular respiration. But that wasn’t my question which concerns the rapid weight loss experienced by folk starting a Keto Diet. $\endgroup$ – adlibber Oct 18 '18 at 6:21

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