It’s often claimed that Glycogen stores are reduced in Low Carb diets. I wondered by just how much and there’s a paper out there which has specific numbers in it (Scandinavian Journal of Clinical and Laboratory Investigation Volume 32, 1973 – Issue 4. Pages 325-330. Liver Glycogen in Man –- the Effect of Total Starvation or a Carbohydrate-Poor Diet Followed by Carbohydrate Refeeding. Depts. of Gastroenterology and Clinical Chemistry, L. Hson Nilsson & E. Hultman, S:t Eriks Sjukhus, Stockholm, Sweden & E. Hultman).
Liver glycogen content was determined in specimens obtained by repeated percutaneous biopsies during starvation and under various dietary conditions in 19 human subjects. During rest and following an overnight fast, there was a decrease in liver glycogen content by a mean of 0.30 mmol glucosyl units per kg wet liver tissue per min during a further 4 hours’ starvation. Prolonged starvation or carbohydrate-poor normocaloric diet decreased the liver glycogen from a mean of 232 to 24–55 mmol glucosyl units per kg within 24 hours. During an additional period of up to 9 days on the carbohydrate-poor diet the liver glycogen remained at a low level. Refeeding with a carbohydrate-rich diet gave a rapid increase of the liver glycogen to supernormal values, 424–624 mmol glucosyl units per kg wet liver tissue.
Wow! That’s a pretty dramatic drop in liver glycogen in just 24 hours.
Maybe even more amazing is the very fast refill to 2x-3x the “normal” levels. That goes a long way to explaining weight gain when leaving the Low Carb diet.
As a reference on the liver (Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.Chapter 94 Evaluation of the Size, Shape, and Consistency of the Liver. Douglas C. Wolf.)
The liver weighs 1200 to 1400 g in the adult woman and 1400 to 1500 g in the adult man.
According to this article:
Liver glycogen provides about 400 calories or 100 grams of glycogen
If there’s 3-4 grams of water with every gram of glycogen that’s a total of 400-500 grams that are lost with reduction in glycogen. That’s less than 1 lb but a significant portion of a typical liver size (around 1/3 of the size).