Sunday, May 27, 2012

Glucose and glycogen

I tried to make this as easy to understand as I could. It's really a bit LOT more complicated than this, but I took a few things out that I will probably add to another post and I tried to just leave the meat (pun intended!) of it. There are just so many processes going on in your body when it comes to food and metabolism. But this is a little info on glucose and low-carb diets.
Let me know if you have any questions. 

You use your skeletal muscle to move and function. Biceps, quads, calves, abs, etc. The main source of fuel for your muscles is glucose. A type of sugar, or carbohydrate. When the muscle is working, it is burning glucose. But what happens when glucose is low?

When the body has more glucose in the blood than is being used (say you just had an ice cream binge), your body stores glucose in another form called glycogen. This is just a very large molecule made up a a whole bunch of glucose molecules. You store glycogen in your skeletal muscle (biceps, abs, quads, etc) as well as in your liver. When you consume glucose, it will first go to your muscles to see if they need it. If your muscles have plenty of glucose, it gets turned into glycogen in your muscles. If your muscles have plenty of glucose and glycogen, it's off to the liver. Your liver then checks its glycogen levels. If those are low, the glucose is converted to glycogen and stored in your liver. If glucose gets to your liver and and the liver's glycogen levels are fine, the glucose is then turned into (every one's favorite): fat.

Your liver can store about 100g of glycogen and your muscles can store approximately 400g of glycogen.
Also, when glycogen is stored in your muscle for every gram of glycogen you store about 2-3 grams of water, so if your muscles are low and you eat carbs (particularly starch which is made up entirely of glucose) you are not suddenly gaining huge amounts of fat, you are probably storing water. This is also why when you go low-carb you lose a lot of water weight.

So how do you keep it from turning to fat? Simple: exercise.

Exercise is your best friend, for a lot of reasons.

For this one in particular, when you exercise, you use up that glucose and glycogen. But you will want to make sure you are using a lot of different muscle groups. If you just run or just do sit ups you are mainly only targeting one muscle group. And the thing about muscles is that they don't like to share. They lack the necessary enzyme required to give up glycogen to other muscles. So, say you do 500 sit ups and deplete the glycogen in your abs, you will not take glycogen from your arms or legs or anywhere else. You will start to tear down the protein in your abs.

This is not all bad.


And you want to replenish it (believe it or not).

The major fat burner in your body is muscle. This is one of the reasons you know so many men who can eat so much without getting fat. They have more muscle. Building muscle is what I like to call “preventative damage control”. The more lean muscle you have, the more you can actually eat without getting fat.

By working your muscles, you tear them down. If you don't replenish them, they just wither and get smaller and you would be better off having not worked out in the first place. You are DECREASING your overall fat burning. If you don't replenish your muscle with some protein within a reasonable amount of time, you will decrease your muscle mass and the next time you DO eat, it is more likely to be turned into fat.

For this, I highly recommend a whey protein supplement. Research shows that the ideal amount of protein to get after a workout is 25g. You shouldn't need more than that. And most whey protein powders have that much in once scoop for only about 140 calories. I wouldn't make this your life's greatest source of protein (I won't get too into protein right now, I'll save that for a later post) but it is probably the best thing you can do for worn out muscles immediately after exercise.


And no, you won't “bulk up” unless you are taking steroids. Seriously. If you are female (and I know I have some male readers, some of you may want to bulk up, but if not, then just stick to a lighter workout, nothing too intense), you will not get all huge. You don't have the hormones to do so. You will only look leaner and slimmer.

This brings me to another point: Fat burning exercise.
Many people will tell you to work out at a lower intensity because it “burns more fat”.

This is not the case.

Yes, at a lower intensity, the percentage of calories you are burning from fat (vs carbs) is greater than it is at a high intensity.

Let's say at a high intensity you are burning 50% carbs and 50% fat while at a lower intensity you are burning 30% carbs and 70% fat. Sounds better huh?

Well, if I was offering you money, which would you rather have: 70% of $100 or only 50% of $1000.


You would rather have the 50%. Because 70% of 100 is only $70 but 50% of 1000 is $500!

So the absolute amount is more. When you exercise at a high intensity, yes, you lower the percentage of fat you are burning. But you are burning an overall amount of fat higher than you were at a low intensity. Does that make sense?

Also, when you exercise and you deplete your glycogen, you get a surge in the enzyme that makes glycogen which means you can eat carbs after exercising without it turning into fat.

So, what happens if you don't have carbs?

Your muscles run off of glucose (a carbohydrate). When they don't have it, they can make it. What they like to make it out of, is protein.

Proteins are made up of repeating chains of amino acids. When you eat protein, your body breaks it down into amino acids and your body utilizes those however it needs to (it does to in a lot of ways, EAT YOUR PROTEIN, IT IS IMPORTANT).

One of the things it does, is keeps a “pool” of free amino acids to be used for whatever processes may need it. For example, when your glucose is low, Your body can MAKE glucose out of the free amino acids your body has stored.

However, you need to be eating enough protein. If you aren't, you will deplete your storage of free amino acids and your body will take protein from your muscles to use for glucose. This is not good because as was stated before, you WANT muscle. The last thing you want to do is diminish it. So if you are going to be going low carb, make sure you keep your protein up! Otherwise, it is useless. This is when you will lose muscle, lower your fat burning ability, and slowly get fatter over time. If you keep your protein up, your body will have enough to replenish your muscles and turn some into glucose.

Another popular low-carb fat-burner is getting your body into ketosis (which some of you may be familiar with) and I would love to tackle another time. That is when your body doesn't have enough glucose and in order to spare your muscles, makes what are called ketone bodies, which are used instead of glucose.
But it is late and this post is long enough. I would be surprised if most of you even read this far (tho I hope you did).

Take care! And get your protein!


  1. great amount of info.. I have been so obsessed with glucose and carbs ever since the gestational diabetes.. Explains things alot :) Thanks for this post :)

  2. Nice to read something by a personal blogger who actually knows what they're talking about. A lot of people with EDs are protein deficient to begin with, and they eat nothing but carbs which only complicates things. Not only is protein important, but so is fat, which helps fuel ketosis better than protein does, but I'm assuming you'll probably touch on that in your next post.