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I'm a physician doctor with an MD degree. My passion for teaching has always been appreciated by students with whom I have shared my knowledge. I'm a passionate teacher of medical biochemistry and would like to share my knowledge about this beautiful subject with all those who is interested to learn to understand the cellular metabolic events and to understand the metabolic disease process. I would like to learn new things by keeping myself updated with current research in the field. Let us share the knowledge each other!!

Thursday, February 21, 2013


Most of us believe that just by skipping breakfast and lunch we are going to loose weight and achieve that imaginary figure that we always want to have!!! By skipping breakfast we are basically allowing our body to get into fasting condition because of the long time gap since last dinner. This will lead to low glucose level in our blood and that makes alpha-cells of our pancreas to release glucagon.  

Glucagon will try to increase blood glucose level. So the immediate source for it is the glycogen stored in the liver!! It will break the liver glycogen to release glucose into blood stream which can be used by red blood cells and the neurons. But the glycogen can last for few hours depending on individuals glycogen reserve. The glycogen reserve can last anywhere from 12 hrs-24 hrs depending on the amount of carbohydrate diet consumed since three day prior to the fasting. Since people who use fasting as a means of loosing weight will hardly have any glycogen reserve!!! 

So when glycogen reserve is exhausted then which is the next source of glucose for glucagon???  The next source of glucose for glucagon is skeletal muscle protein!!! Surprised, yes, under fasting condition and starvation, our skeletal muscle will breakdown to release amino acids into blood stream. Amino acids will be taken up by the liver, mainly as alanine, and will be converted to glucose by GLUCONEOGENESIS!! The glucose produced will be released into blood stream which will be used mainly by red blood cells and neurons. You can observe the graph below for the time line for various metabolic events!! 

Click on the slide picture below for better visualization!!!

This process will continue for next seven days, by seven days of starvation, our body would have lost 60% of muscle mass!! At this time, body will stop breaking muscle protein and will adopt itself to use fatty acid derived products called ketone bodies. Ketone bodies will be synthesized by liver under the influence of glucagon. The source for ketone bodies is adipose tissue fatty acids present in the form of triacylglycerol. 

Triacylgllycerol breakdown from adipose tissue (lipolysis) generally begins with glycogen degradation but will be at very basal level until seven days of starvation. A week after starvation, lipolysis predominates and will produce significant amounts of ketone bodies which will flood our blood stream. Brain by this time will adopt itself to use ketone bodies but red blood cells will survive only on glucose which now comes from gluconeogenesis process from glycerol!!

So when someone is using short term fasting as a means of losing weight, they basically are losing their skeletal muscle!! So stop fasting and have low carbohydrate, low fat and high protein diet to lose weight!! 

In my next blog I will explain why low carbohydrate, low fat and high protein diet will help to lose weight!!!

You are most welcome to leave your comments or e-mail me for your queries at  prakashmungli@gmail.com


Evelyn B said...

Dr. Mungli wouldn't these people develop ketoacidosis ? Or are most of the ketone bodies utilized to the point where it is not toxic?

Dr.Prakash Mungli, MD said...

Hi Evelyn,
When on high protein and low carb diet, generally you keeping constant amount of gluconeogenesis and fatty acid oxidation to maintain normal to lower normal blood glucose level. So as the fatty acid oxidation is releasing acetyl CoA it enters into TCA cycle to yield NADH and FADH2 which enters into ETC to produce ATPs. So generally acetyl CoAs do not accumulate to such an extent to produce ketoacidosis!! So the point is, by consuming high protein and mole carb diet one is maintaining significant gluconeogenesis and basal levels of fatty acid oxidation thereby it helps in lipolysis and loss of adipose tissue!!! Hope this helps.

Evelyn B said...

Interesting. Thank you Dr. Mungli.

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