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A synopsis of study about whether glycogen can be stored as fat

Hi all!

There has been much discussion here on whether glycogen can be stored as fat. Curious, I decided to do some research, and I just finished reading this research study on how glycogen is stored as fat.

You can read the study yourselves at the link provided below. But if you’re not inclined, I wrote my own description of the study (very basic description indeed, there is a lot of information unrelated to our question that I didn’t include), and then I followed up with some of the relevant points afterward.  I wrote salient points in bold in case you don't have time to read every sentence. 


For those of you who aren't inclined to read any further, here's the bottom line: Glycogen CAN be converted to fat, but it has to jump through a lot of interesting hoops to get there.  


But please try to read the original study for yourselves, just in case I misread or omitted something. It is not my intention to mislead anyone at all! 

Is this the absolute end of this discussion? I doubt it, since this is only one study. But what I found is that is proves everyone right, more or less! LOL


Kevin JAcheson, PhD; Yves Schutz, PhD; Thierry Bessard, MD; Krishna Anantharaman, PhD; 

Jean-Pierre Flail, PhD; and Eric Jaquier, MD 

Accessed at: http://www.ajcn.org/content/48/2/240.full.pdf.

A very simple description of the study:

The experiment lasted for 14 day and involved three men all of similar athletic ability and physique. During the first three days, the subjects glycogen stores were depleted to near zero; then from days 4 through 12 (9 days in all), the subjects were overfed on a high-carbohydrate, low-fat diet. Approximately 3600 extra carbohydrate calories per day were needed to produce an overfeeding condition. Subjects also exercised twice a day (30 mins each time) and they could do additional exercise, but they were not allowed to do any anything strenuous (other than the two assigned workouts). It took approximately 4 days for the subjects’ glycogen stores to be filled, but it was after day 2 that glycogen began converting to fat (this was once their glycogen storage sites had reached a minimum level of 500 grams of glycogen). By the end of the overfeeding period (9 days), the three subjects gained on average 4.6 kg. Of that it was calculated that 2.84 kilos was water weight (glycogen requires 2-4 times the amount of water for storage), 665 grams (about 1.5 lbs) was muscle growth, and the remaining 1.1 kilos was fat. Subjects weights returned to their beginning weights two days after the overfeeding period.


Definition: de novo lipogenesis: conversion of glycogen to fat

Here are some of the interesting findings of this study.

1. When overeating on carbs the first thing that is done with the excess glycogen is to fill glycogen storage sites in the muscles and liver


2. According to the discussion provided in this research, it is pretty hard to fill all glycogen storage sites and then to maintain them. This study showed that muscles can store 800-900 grams of glycogen before becoming saturated. Extremely fit people can store 1 to 1.1 kilos of glycogen. The storage cites have to fill by at least 500 grams before fat synthesis can begin.


3. This study also showed that it is very difficult to maintain a saturated state of the muscles, since the glycogen is constantly being used, and presumably because the average person won’t eat sufficiently of carbs to ever get to saturation. Too, there is our fitness level, which determines how effectively we can fill and maintain our glycogen stores. 


4. Interestingly, the subjects in the study spontaneously burned more calories during the 9 days of over-feeding, too; so the scientists had to keep increasing calories to maintain an over-feeding state. On average, test subjects spontaneously burned an extra 840 calories per day, or 35% more calories, during the overfeeding period, presumably due to thermic effect (thermogenesis).Yes, you read that right: A high-carbohydrate diet causes the body to spontaneously burn more calories~up to 35% more calories than a high-fat or high-protein diet.


5. Only once the glycogen stores are filled to at least 500 gram capacity is the remaining glycogen able to be converted to fat. The body is capable of converting up to 500 grams of glycogen to fat per day. 


6. But de novo lipogenesis (glycogen to fat storage) doesn’t produce an equivalent amount of fat. That is 1 kg of glycogen doesn’t convert to 1 kg of fat. It converts to much less fat than that.  Since it takes about 25% of the glycogen calories to convert it to fat, only some 75% of glycogen excess makes it into fat.


7. Bottom line: Yes, glycogen can be converted to fat (de novo lipogenesis), but it takes a lot of excess for this to occur.


I would love to hear your responses to this study!  .........ana xoxo

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ALL muscle is built when doing no exercise. You 'break' the body down and then you get fitter as you sleep/rest/recover.

Its true in that to get fitter you have to stop training and let the body recover.

Ok build muscle when you break them down. But build them 1.5 pound in such a short period of time, it seems a lot to me!

Yeah, Sandro, I found this really intriguing. These guys were instructed to workout on a stationary bike for 30 minutes, twice a day. They could do more, if desired, but they were instructed to not do anything strenuous. So, if this muscle gain were indeed true (and there isn't anything to doubt it), I'd say the body is amazing!

(As an aside, when I started eating 811 rv, and without changing anything in my workout routine, I noticed that my muscles looked much rounder. Maybe had something to do with the water stored with glycogen? Maybe I was gaining muscle like these guys? Don't know. But I love the effect!)   ....ana xoxo


Well, it is possible that there were catabolic effects previously. People can and do replace muscle without excercising, if they consume an excess of calories and protein consistently - If they already lost the muscle. Perhaps the calorie restriction glycogen repletion diet promoted catabolism of muscle tissue. This is common in calorie restriction diets. It is assumed that high protein intakes can offset these effects but perhaps this wasn't as efficient as thoguht. Or perhaps there was a previous history of catabolism of muscle tissue. I did think it was an interesting part of the study too.

Take care

Adam x

Maybe I can pay a troll to make up a collage of the fruit bats and how skinny everyone is despite all the simple sugar phobia getting around the net today.

That would be funny. "811 POW's worry about getting fat on fruit".

Anyone know any fat longterm carb guzzlers? I don't. Im always looking though.

It reminds me of my mate that would peddle very lightly cos he was worried he would twist his bike frame from too much force on the pedals...AINT gonna happen lol!

Picking an arbitrary number of calories you need is not realistic for optimal health. It can be a good starter but it needs to be tweaked depending on numerous factors.

Freelee and Durianrider probably vary what they eat depending on their activity levels. They don't look like hippos because they are very in tune with how much nutrition and fuel they need each day. I bet Durianrider will jump from 4K calories to 7-8K calories during a long ride and drop down again to half that days later. Fill your tank with healthy foods but don't overstuff yourself when there is no need to.

A sedentary 50Kg woman eating 5K a day can gain a good deal of weight as she's not really in tune with her body but she can also look awesome if she does everything her body needs to look good. 5k a day might be reserved for days she burns 2K calories that day exercising but not if she's sedentary that week.



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