Today is the first day of our five part series from Cryus Khambatta, aka Mangoman. Cyrus developed this series to help people better understand the effects of food and exercise on diabetes.
Day 1: A Crash Course in Nutrient Metabolism
By Cyrus Khambatta, Ph.D.
If you’re like many people, you may have heard the term “insulin resistance” before, but don’t fully understand what it means or how it applies to your health as a diabetic or prediabetic. Understanding insulin resistance is the key to taking control of your health as a diabetic, and for establishing excellent blood glucose control.
When you eat food, the food is mechanically digested in your stomach and then passed to your intestine so that the nutrients can be absorbed into your bloodstream. These “macronutrients” include carbohydrates, protein, and fat. Once in your bloodstream, carbohydrates, protein and fat circulate until they find a home in a tissue like the brain, liver, pancreas, muscle, fat etc.
The blood is merely a highway system for nutrients. Body tissues are the destination for nutrients.
When you eat carbohydrates, the enzymes in your mouth and intestine break apart long chains of glucose molecules into individual pieces. Those pieces are then absorbed into your bloodstream, which is why blood glucose levels increase after you eat carbohydrates.
Once glucose is in circulation in your bloodstream following a meal containing carbohydrates, two things happen:
(1) The pancreas senses how much glucose was ingested, then responds by secreting insulin into the bloodstream.
(2) Tissues in your body are designed to “vacuum” the glucose out of circulation and either use it for energy or store it for the future use.
This system can be pretty complicated, so take a look at the simple diagram below to understand how this system works:
A Crash Course in Nutrient Metabolism. When carbohydrates are eaten, they are broken down into glucose molecules. The pancreas senses the amount of glucose in the bloodstream, then secretes insulin in response. Insulin then signals to the liver, muscle, and fat tissue to uptake or “vacuum” the glucose out of the bloodstream and into the tissue. Even though only the liver, muscle, and fat are shown to respond to insulin in this diagram, insulin is used by most tissues In the body to allow for the uptake and usage of glucose. Note that the brain, liver, muscle, and fat are the largest consumers of insulin.
Insulin
Insulin is a hormone which is released by the pancreas in response to rising blood glucose. When you consume carbohydrate energy, the glucose that enters the bloodstream knocks on the door of the beta cells in the pancreas as a signal to make insulin. The beta cells then make insulin, and secrete it into the bloodstream so that tissues such as the liver, muscle, and fat can vacuum up glucose in the blood.
Why is insulin important? Insulin is critically important in this system for one main reason:
Insulin serves as the key that unlocks the door to allow glucose to enter body tissues.
Without insulin, cells in the liver, muscle, and fat have a difficult time vacuuming up glucose from the blood. These tissues are capable to vacuuming up only a small percentage (5-10%) of the glucose in circulation without the help of insulin. When insulin is present, the amount of glucose that can be transported into tissues significantly increases, allowing tissues to be properly fed, and keeping blood glucose concentrations in the normal range.
Understanding the Glucose “Vacuum” Concept
Throughout this course I will use the term “vacuum” to describe the movement of glucose from the bloodstream and into the tissues. Even though no such vacuum actually exists, the concept of a vacuum is easy to understand, and lets us begin to understand that glucose circulates in the bloodstream until it is taken up by a body tissue to be burned for energy or stored for later.
The concept of the glucose vacuum is simple, and is depicted in the following diagram:
Introducing the Glucose Vacuum. Glucose molecules circulate in the bloodstream in order for body tissues to vacuum them from circulation. The concept of the glucose vacuum is meant to establish a one-way route for glucose movement, originating in the bloodstream and ending in tissues such as the brain, liver, muscle, and fat. Insulin accelerates the movement of glucose into body tissues, strengthening the glucose vacuum. The movement of glucose out of the bloodstream keeps blood glucose values from going high following a carbohydrate-rich meal.
The important thing to know is that insulin is required by most tissues to vacuum the glucose out of circulation. When the glucose vacuum is strong, then glucose quickly leaves the bloodstream and enters tissues to be stored or burned for energy. When the vacuum is weak, glucose remains in the bloodstream, resulting in high blood glucose values.
Your Brain is Selfish!
The tissue in your body that is hungriest for glucose is your brain. Your brain is a very unique organ for a number of reasons, but is important in this context simply because your brain has one choice for fuel at all times – glucose. The brain is powered by glucose for 99% of your waking life, and does not possess an ability be powered by either fatty acids or protein. In addition, your brain cannot store glucose as glycogen, instead it must use glucose on an “on-demand” basis, by vacuuming glucose from the bloodstream at all times. Because of this, maintaining sufficient glucose in your bloodstream is vitally important for cognitive function.
If you’re a diabetic, then you may have felt the symptoms of low blood glucose (hypoglycemia). This occurs when the level of glucose in your bloodstream falls below the low threshold of 70 mg/dL. One of the first symptoms that most diabetics experience during hypoglycemia is a feeling of confusion, lightheadedness, a loss of balance, slurred speech, and impaired vision. All of these symptoms are related to cognitive function.
Why do you think this is the case?
Well, given what we know about the brain’s ability to use only glucose as fuel, when the concentration of glucose in the bloodstream falls below 70 mg/dL, the brain is one of the first organs to recognize a problem. In this situation, your brain is literally being starved for fuel, which results in feelings of confusion, lightheadedness, and slurred speech. This situation can be very dangerous and even fatal, which is why it is very important to ensure that you recognize the symptoms immediately, then consume carbohydrate energy to bring blood glucose levels back to the normal level.
The Liver, Muscle and Fat are Glucose Hogs!
Aside from your “glucose-selfish” brain, the tissues in your body outside of your central nervous system (CNS) that are hungriest for glucose are the liver, muscle and fat. These tissues are the largest consumers of glucose, meaning that they vacuum most of the glucose out of the bloodstream. It is very important to understand one thing about glucose which is often misunderstood.
Glucose is a molecule which can be used by EVERY tissue in your body for energy.
This is important because as diabetics, we’ve come to fear blood glucose without understanding that this is the very molecule that many tissues in your body are designed to use as fuel.
A Basic Definition of Insulin Resistance
Insulin resistance is determined by the effectiveness of insulin to allow glucose to enter body tissues. In other words, insulin resistance is a measure of the ability of insulin to start the glucose vacuum in your liver, muscle and fat tissue and keep glucose out of the bloodstream.
How much insulin is required to do this job? If tissues require a lot of insulin in order to start the glucose vacuum, then those tissues are considered insulin resistant. On the other hand, if tissues require only a small amount of insulin in order to start the glucose vacuum, those tissues are considered insulin sensitive.
Our goal as diabetics is to get our tissues to use the smallest amount of insulin to vacuum the largest amount of glucose out of the bloodstream.
The less insulin required to initiate the glucose vacuum, the more efficient the tissue. The more insulin required to initiate the glucose vacuum, the more inefficient the tissue. Therefore, one way to define insulin resistance is as follows:
Insulin resistance is a condition of inefficient muscle, fat, and liver tissue.
Insulin resistance is the opposite of insulin sensitivity.
This is your lesson for the day. If you’re a diabetic, think about the number of units of insulin you use on a daily basis, and whether that number has increased or decreased over time. Smaller numbers indicate good insulin sensitivity whereas larger numbers bad insulin sensitivity. Here’s a graphic to drive home this concept:
Insulin Sensitivity is the Opposite of Insulin Resistance. Insulin sensitive tissue requires a small amount of insulin in order to vacuum large amounts of glucose out of the bloodstream. Insulin resistant tissues require large amounts of insulin in order to vacuum large amounts of glucose out of the bloodstream. Making large amounts of insulin cause significant stress to the beta cells in the pancreas.
In the next lesson we’ll cover the causes of insulin resistance. Stay tuned for more fun.
Cyrus Khambatta, PhD, is the founder of Mangoman Nutrition and Fitness He received a PhD in Nutritional Biochemistry from UC Berkeley, and has studied the biology of pancreatic beta cell failure for over a decade. Cyrus was diagnosed as a type 1 diabetic at the age of 22, and has found ways to make managing diabetes enjoyable. Cyrus has taught courses at UC Berkeley, and continues to impact diabetics across the globe. He is a vegan, a competitive athlete, and a mango fanatic. Cyrus holds the unofficial world record for most mangoes eaten in a 3-month period: 1,750. Every year Cyrus holds Mangofest, a celebration of the mango and a chance for the community to play mango-inspired games.
Day 1: A Crash Course in Nutrient Metabolism
By Cyrus Khambatta, Ph.D.
If you’re like many people, you may have heard the term “insulin resistance” before, but don’t fully understand what it means or how it applies to your health as a diabetic or prediabetic. Understanding insulin resistance is the key to taking control of your health as a diabetic, and for establishing excellent blood glucose control.
When you eat food, the food is mechanically digested in your stomach and then passed to your intestine so that the nutrients can be absorbed into your bloodstream. These “macronutrients” include carbohydrates, protein, and fat. Once in your bloodstream, carbohydrates, protein and fat circulate until they find a home in a tissue like the brain, liver, pancreas, muscle, fat etc.
The blood is merely a highway system for nutrients. Body tissues are the destination for nutrients.
When you eat carbohydrates, the enzymes in your mouth and intestine break apart long chains of glucose molecules into individual pieces. Those pieces are then absorbed into your bloodstream, which is why blood glucose levels increase after you eat carbohydrates.
Once glucose is in circulation in your bloodstream following a meal containing carbohydrates, two things happen:
(1) The pancreas senses how much glucose was ingested, then responds by secreting insulin into the bloodstream.
(2) Tissues in your body are designed to “vacuum” the glucose out of circulation and either use it for energy or store it for the future use.
This system can be pretty complicated, so take a look at the simple diagram below to understand how this system works:
A Crash Course in Nutrient Metabolism. When carbohydrates are eaten, they are broken down into glucose molecules. The pancreas senses the amount of glucose in the bloodstream, then secretes insulin in response. Insulin then signals to the liver, muscle, and fat tissue to uptake or “vacuum” the glucose out of the bloodstream and into the tissue. Even though only the liver, muscle, and fat are shown to respond to insulin in this diagram, insulin is used by most tissues In the body to allow for the uptake and usage of glucose. Note that the brain, liver, muscle, and fat are the largest consumers of insulin.
Insulin
Insulin is a hormone which is released by the pancreas in response to rising blood glucose. When you consume carbohydrate energy, the glucose that enters the bloodstream knocks on the door of the beta cells in the pancreas as a signal to make insulin. The beta cells then make insulin, and secrete it into the bloodstream so that tissues such as the liver, muscle, and fat can vacuum up glucose in the blood.
Why is insulin important? Insulin is critically important in this system for one main reason:
Insulin serves as the key that unlocks the door to allow glucose to enter body tissues.
Without insulin, cells in the liver, muscle, and fat have a difficult time vacuuming up glucose from the blood. These tissues are capable to vacuuming up only a small percentage (5-10%) of the glucose in circulation without the help of insulin. When insulin is present, the amount of glucose that can be transported into tissues significantly increases, allowing tissues to be properly fed, and keeping blood glucose concentrations in the normal range.
Understanding the Glucose “Vacuum” Concept
Throughout this course I will use the term “vacuum” to describe the movement of glucose from the bloodstream and into the tissues. Even though no such vacuum actually exists, the concept of a vacuum is easy to understand, and lets us begin to understand that glucose circulates in the bloodstream until it is taken up by a body tissue to be burned for energy or stored for later.
The concept of the glucose vacuum is simple, and is depicted in the following diagram:
Introducing the Glucose Vacuum. Glucose molecules circulate in the bloodstream in order for body tissues to vacuum them from circulation. The concept of the glucose vacuum is meant to establish a one-way route for glucose movement, originating in the bloodstream and ending in tissues such as the brain, liver, muscle, and fat. Insulin accelerates the movement of glucose into body tissues, strengthening the glucose vacuum. The movement of glucose out of the bloodstream keeps blood glucose values from going high following a carbohydrate-rich meal.
The important thing to know is that insulin is required by most tissues to vacuum the glucose out of circulation. When the glucose vacuum is strong, then glucose quickly leaves the bloodstream and enters tissues to be stored or burned for energy. When the vacuum is weak, glucose remains in the bloodstream, resulting in high blood glucose values.
Your Brain is Selfish!
The tissue in your body that is hungriest for glucose is your brain. Your brain is a very unique organ for a number of reasons, but is important in this context simply because your brain has one choice for fuel at all times – glucose. The brain is powered by glucose for 99% of your waking life, and does not possess an ability be powered by either fatty acids or protein. In addition, your brain cannot store glucose as glycogen, instead it must use glucose on an “on-demand” basis, by vacuuming glucose from the bloodstream at all times. Because of this, maintaining sufficient glucose in your bloodstream is vitally important for cognitive function.
If you’re a diabetic, then you may have felt the symptoms of low blood glucose (hypoglycemia). This occurs when the level of glucose in your bloodstream falls below the low threshold of 70 mg/dL. One of the first symptoms that most diabetics experience during hypoglycemia is a feeling of confusion, lightheadedness, a loss of balance, slurred speech, and impaired vision. All of these symptoms are related to cognitive function.
Why do you think this is the case?
Well, given what we know about the brain’s ability to use only glucose as fuel, when the concentration of glucose in the bloodstream falls below 70 mg/dL, the brain is one of the first organs to recognize a problem. In this situation, your brain is literally being starved for fuel, which results in feelings of confusion, lightheadedness, and slurred speech. This situation can be very dangerous and even fatal, which is why it is very important to ensure that you recognize the symptoms immediately, then consume carbohydrate energy to bring blood glucose levels back to the normal level.
The Liver, Muscle and Fat are Glucose Hogs!
Aside from your “glucose-selfish” brain, the tissues in your body outside of your central nervous system (CNS) that are hungriest for glucose are the liver, muscle and fat. These tissues are the largest consumers of glucose, meaning that they vacuum most of the glucose out of the bloodstream. It is very important to understand one thing about glucose which is often misunderstood.
Glucose is a molecule which can be used by EVERY tissue in your body for energy.
This is important because as diabetics, we’ve come to fear blood glucose without understanding that this is the very molecule that many tissues in your body are designed to use as fuel.
A Basic Definition of Insulin Resistance
Insulin resistance is determined by the effectiveness of insulin to allow glucose to enter body tissues. In other words, insulin resistance is a measure of the ability of insulin to start the glucose vacuum in your liver, muscle and fat tissue and keep glucose out of the bloodstream.
How much insulin is required to do this job? If tissues require a lot of insulin in order to start the glucose vacuum, then those tissues are considered insulin resistant. On the other hand, if tissues require only a small amount of insulin in order to start the glucose vacuum, those tissues are considered insulin sensitive.
Our goal as diabetics is to get our tissues to use the smallest amount of insulin to vacuum the largest amount of glucose out of the bloodstream.
The less insulin required to initiate the glucose vacuum, the more efficient the tissue. The more insulin required to initiate the glucose vacuum, the more inefficient the tissue. Therefore, one way to define insulin resistance is as follows:
Insulin resistance is a condition of inefficient muscle, fat, and liver tissue.
Insulin resistance is the opposite of insulin sensitivity.
This is your lesson for the day. If you’re a diabetic, think about the number of units of insulin you use on a daily basis, and whether that number has increased or decreased over time. Smaller numbers indicate good insulin sensitivity whereas larger numbers bad insulin sensitivity. Here’s a graphic to drive home this concept:
Insulin Sensitivity is the Opposite of Insulin Resistance. Insulin sensitive tissue requires a small amount of insulin in order to vacuum large amounts of glucose out of the bloodstream. Insulin resistant tissues require large amounts of insulin in order to vacuum large amounts of glucose out of the bloodstream. Making large amounts of insulin cause significant stress to the beta cells in the pancreas.
In the next lesson we’ll cover the causes of insulin resistance. Stay tuned for more fun.
Cyrus Khambatta, PhD, is the founder of Mangoman Nutrition and Fitness He received a PhD in Nutritional Biochemistry from UC Berkeley, and has studied the biology of pancreatic beta cell failure for over a decade. Cyrus was diagnosed as a type 1 diabetic at the age of 22, and has found ways to make managing diabetes enjoyable. Cyrus has taught courses at UC Berkeley, and continues to impact diabetics across the globe. He is a vegan, a competitive athlete, and a mango fanatic. Cyrus holds the unofficial world record for most mangoes eaten in a 3-month period: 1,750. Every year Cyrus holds Mangofest, a celebration of the mango and a chance for the community to play mango-inspired games.
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