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Weightloss Exposed

What happens in your body when you eat, fast or workout?

by Ron

The key to understanding some basics about your diet, metabolism and weight loss is  BLOOD SUGAR.

Every second of every day our body is battling it out to keep our blood sugar levels relatively constant during changing dietary intake.  Ironically, the enemy is food.  Although necessary, too little means we starve, too much and we put on the pounds.  In today's society, the scales are tilted toward weight gain through fast food and ease of travel.  I will discuss in laymen's terms why we gain or lose weight.

BUT FIRST...

 

Terms
Amino Acids Individual subunits of protein. 
ATP Direct energy used by the body from breakdown products of carbohydrates, fats and proteins.
Carbohydrate Many different simple sugars hooked together into a long chain.  Pasta, rice, potatoes, bread.
Fatty Acids   The 'free' form of fat.  Fatty acids circulate in the bloodstream for uptake by the liver and muscles for conversion into energy.
Glucose   A simple sugar (one unit - monomer) used as the bodies primary energy source.  Fruits and juices have simple sugars.
Glycogen THE stored form of glucose, a polymer (many glucose units hooked together).  If we only had glycogen as an energy source, we would only live for 12 hours (some fat is good).
Ketone Bodies Made in the liver from fatty acids.  A secondary energy source of many organs.  Ketone bodies are a storage form of energy similar to glycogen.
Protein Many amino acid units together in a chain. Component of muscles and blood plasma.  Chicken, Steak.
Triacylgycerol Stored form fat.  Made from fatty acids.  Stored in in adipocytes - adipose tissue.

**All of the above terms are major energy sources used by the body to be converted to ATP.**
Insulin/Glucagon Hormones made by the pancreas signaling blood glucose levels.

 

Organs and Fuel Reserves
Liver STORES glycogen (7%/wt) to be used to maintain normal blood glucose levels between meals.  USES fatty acids for its own fuel.
Muscles USES blood glucose, ketone bodies and free fatty acids (from blood) for energy, STORES small amounts of glycogen for extreme exertion.
Brain USES blood glucose primarily for energy and stored ketone bodies during fasting or starvation  - cannot use free fatty acids directly.  STORES very little energy reserves.
Heart   USES blood glucose, fatty acids (from blood) and ketone bodies for energy.  STORES very little energy reserves.
Adipose (fat) tissue STORES the free fatty acids from the bloodstream as triacyglycerols.

 

Some basic facts you need to know:
1 The liver regulates EVERYTHING.  It all goes down in the liver.  The liver cells are hepatocytes.  It is solely their job to convert all the sugars, amino acids and fatty acids that the intestines produced from digestion into whatever the body needs or doesn't need.  The liver is the bodies distribution center.  It converts everything we bring in during digestion into whatever the body needs and then ships it out to whoever needs it..
2 Blood glucose levels need to stay relatively CONSTANT all the time ~4.5mM.  Blood sugar is the first source of food for the brain.  All humans need their brains although some people (to remain nameless) still don't know how to use them.
3 The body can tell if there is too little or too much blood sugar by the amounts of two pancreatic hormones:  INSULIN and GLUCAGON. The liver, in turn, responds to these hormones. 
4 When the blood sugar is high, the pancreas releases INSULIN into the bloodstream.
5 When the blood sugar is low, the pancreas releases GLUCAGON into the bloodstream.

 

See diagram - Insulin/Glucagon Regulation

We are now ready to begin our discussion.  

The body in-between meals or overnight.

Blood sugar levels are decreasing since our organs are using it as their primary energy source (brain, heart, muscles).  In response, the pancreas makes LESS insulin and MORE glucagon.  This tells the liver to convert it's storage energy GLYCOGEN into blood glucose to get back to normal blood glucose levels.  Remember, this is for the brain primarily but also for the heart and muscles...very important!

If I am exercising.

Blood sugars have decreased as before, LOW insulin/HIGH glucagon levels.  Liver and muscle glycogen is mostly all used up as the reserves are too small to maintain the blood sugar level indefinitely.  WHAT HAPPENS!!!  We gotta feed the brain!  Well, the HIGH glucagon level tells the adipocytes to convert the triacylglycerols (fat) into free fatty acid to be released into the blood stream.  The LIVER converts the fatty acids into brain food - into glucose or ketone bodies.  The MUSCLES and HEART uptake the bloodstream fatty acids for energy.  The net result is that we have burned fat to lose weight!

See diagrams - Muscle Food & Brain Food

Moderate meal after exercising.

We eat to replenish our body with blood glucose and glycogen since we have LOW insulin/HIGH glucagon levels.  

CARBOHYDRATES will be broken down into individual glucose units.  Other sugars (fructose, galactose, mannose) are converted into glucose too.  The liver will  do many things with this glucose.  First, it will release some into the blood to replenish blood glucose and for muscles to uptake it to store it as glycogen.  The liver will also replenish it's reserves by converting this glucose into glycogen to be used in the next few hours when blood glucose drops again.  See diagram Glucose Metabolism.  

PROTEIN will be broken down into individual amino acids.  The liver uses them to replenish it's own proteins, synthesis of plasma proteins and tissue proteins (to rebuild after a strenuous workout.  See diagram Amino Acid Metabolism.  

FATS are degraded into fatty acids.  In the liver the fatty acids are converted into triacylglycerols for its own energy storage since it prefers fatty acids as its own energy source.  Fatty acids are also sent into the blood for use for by the muscles and heart.  Fatty acids are converted into ketone bodies for the brain and other organs as an energy reserve.   See diagram Fatty Acid Metabolism.  At this point, our insulin levels have risen to normal levels and glucagon levels have lowered to their normal levels.

The body is now sated.  Our energy reserves are replenished for several hours and our insulin/glucagon levels are balanced.  We have made no fat.

Overeating - exercising or not.

Well, all of the above happens to replenish any used up body reserves.  BUT any unused SUGAR from CARBOHYDRATES, AMINO ACIDS from PROTEIN and FATTY ACIDS from FAT will be converted into fatty acids and ultimately into triacylglycerols for storage as fat in adipose tissues - consequently we gain weight.  IT DOES NOT MATTER IF WE EAT 'FAT FREE' OR 'LOW FAT' FOODS because we are just replacing the fats with carbohydrates or protein which will be converted into fats to if we eat too much.

See Diagram - Fat regulation

Starvation

Not recommended.  The body will start breaking down vital proteins for use as blood glucose and ketone bodies to keep the brain, heart and muscles fueled.

See Diagram - Starvation

 

SO HOW CAN I MAINTAIN OR LOSE WEIGHT???

To maintain, you must consume just enough food to replenish blood sugar levels, liver/muscle glycogen and ketone body reserves - simply eat what your body expends.

To lose weight you must:  1) Eat Less  2) Exercise  3) Both

Eating less.  Your blood glucose will be on the low side always, signaling increased glucagon production.  Insulin will remain low.  This tells the body to burn fat since this is the only energy reserve left.  Burning fat will keep the blood glucose levels at an adequate level for the brain, heart and muscles to continue functioning until the fat reserves are depleted.

Exercising too.

Obviously exercising increases your metabolism, you consume more oxygen for respiration.  So the effects of eating less are magnified by exercise so that your fat reserves are burned much, much faster.  Besides losing weight, you will gain all kinds of benefits from increased exercise.  Too mention a few, a healthier mind, body and soul.

Some other pointers are to eat many small meals (4-5) instead of few big meals (2-3).  Infrequent big meals gives us that insulin spike from the infusion of glucose from dietary carbohydrates.  Obviously, all that excess sugar, amino acids and fatty acids will be converted to FAT once our reserves are replenished.  Many little meals (never eat till you are full!!!) will keep your insulin levels lower as your blood glucose will not be fluctuating so much.  Since your insulin levels will be low, glucagon levels will be higher and you will just maintain or even lose weight by fatty acid metabolism from a reduced diet or exercise.

NO SNACKING!!!  Snacking, usually in today's form of low fat high carbohydrate foods, will maintaining a higher blood glucose level signaling insulin production further signaling fat production.  If you snack all day, WHATEVER you are eating will be turned into fatty acids.  Most people think they can eat more if it says ' fat free' or 'low fat' - a very fatal misconception.  Snack on vegetables or fruit - low calories and high in natural vitamins and minerals.  Although they are not as good as chocolate or snack-food, they will fill your stomach.

So...

Moderate Diet + Regular Exercise = 

A Lower Blood Sugar Level =

Low Insulin/High Glucagon Levels=  

Fat Metabolism and Subsequent Weight Loss.

You cannot violate this equation!!!  It is the same as...

Calories in = Calories out,

Calories in - Calories out = Weight gain or loss

CONGRATULATIONS!!!

You have just received an 'A' in Nutritional Biochemistry 101.  With these fundamentals, I hope you may be able to better understand your body and the importance of exercise in today's culture.  Of course applying them is another step.  You have the tools.  It's all you.  

This was just a crash course in biochemistry.  It is very simplified.  But what I have presented are the major points in dietary metabolism.  The body is incredibly complex and there are many other hormones besides insulin and glucagon to regulate metabolism and also many, many other factors that come into play.  But you get the idea.  At least you will be better prepared when you are reading about other diet and nutrition programs so you can choose one that is right for you.

Come on!!!  I am throwing you pearls of wisdom!   Pick them up and run with them!

 

 

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