Why knowing what happens to digestible carbohydrate is important

What happens to the carbohydrates we eat?

Type 2 diabetics (and many others) know they turn into blood sugar. Monitoring blood sugar is something a type 2 diabetic does daily.

But did you know that understanding what happens to blood sugar is also important? I’m not talking about whether it goes up or down after you eat a meal or snack. I’m talking about after the meal and after it has reached its peak – when it starts to go down. The blood sugar goes somewhere. Do you know where it goes?

If you don’t, you should. Because knowing this will help you understand the fate of blood sugar, how you can eat to change this and what impact it will have.

Setting the Stage

It is necessary to define a key term before explaining this process and the image above.

That key term is: digestible carbohydrate. Digestible carbohydrate is the amount of carbohydrate digested by your body after eating a food. For example, one cup of zucchini contains about 12 calories (3 grams) of digestible carbohydrate. By comparison, 1 cup of diced potato contains 28 grams of carbohydrate or 112 calories from carbohydrate. However, it contains only 96 calories of digestible carbohydrate. For most foods, the difference between total carbohydrates and digestible carbohydrate is the difference in fiber content.

In both instances (and all instances of eating food) our body must deal with the digestible carbohydrate calories from the food we eat. In the explanation below, it does not matter where those carbohydrate calories come from (zucchini, potato, cake or ice cream) – the principle is still the same.

The Fate of Blood Sugar

When we eat the zucchini or potato or drink a sugary beverage, there are two outcomes for blood sugar (at least as they relate to this article): 1) some of the blood sugar will be consumed by the body to produce energy; and, 2) the rest will be stored.

The first one is easy to understand. When we eat (or drink) something, our body has to digest it. The act of digesting food is work for the body. Work for the body is done by “burning” or “producing” calories. Glucose can be used to “burn” or “produce” energy needed to do this work. So some of the blood glucose from the foods you eat will be consumed for energy production. But, depending on your circumstance and the amount of digestible carbohydrate you consumed, it is a relatively small amount. This means the rest of the blood glucose needs to be dealt with.

So what happens to the rest?

It gets stored and this is important for you to understand! There isn’t much we can do – one way or the other – to impact the amount of blood sugar that is consumed for energy production. Changing foods we eat, various combinations, whatever the case may be, there isn’t a significant change in the amount of glucose consumed during the digestive process. So this amount (whatever it may be) is pretty stable.

But we can have an impact on storage.

If you return to the image above, there is a cupcake and eggplant on the left hand side. The digestible portion of carbohydrate, that which doesn’t get consumed during the digestive process, gets stored as either glycogen or fat tissue. That’s what the arrows represent.

But how do we know what amounts goes into each and what can do to impact this?

Great questions!

First, our body would prefer to convert glucose to glycogen – the storage form of glucose. The remaining glucose, whatever doesn’t get consumed by producing energy, goes through step 1. This involves converting the glucose to glycogen and storing it – in either muscle tissue or the liver (the only real places our body can store glycogen). Step 1 continues until a condition is met: 1) Our body runs out of glucose that needs to be stored. If this happens, the process stops. Blood sugar is at “normal” levels and nothing else needs to be done. Or, 2) Glycogen levels in both the liver and muscle tissue are full and unable to accept more glycogen. When our body reaches this point, we go to step 2. Step 2 is converting glucose to fat and storing it in the fat tissue. We go through this step until blood sugar is “normal” and nothing else needs to be done.

Limiting Fat Storage

If you go back and look at the image, we can see the middle section (glycogen) dictates how much glucose gets converted to fat and stored in the fat tissue.

With that in mind, there are two things we can do to effectively minimize the amount of glucose that is converted to fat and stored in the fat tissue.

First, we can increase the storage capacity of glycogen. We can do this in one of two ways. By depleting our glycogen stores through dietary changes or exercise; or, by increasing the amount of muscle tissue on our body. Both of these strategies will work to increase the amount of digestible carbohydrate that gets stored as glycogen and decrease the amount of glucose that gets converted to fat and stored as fat tissue.

The second thing we can do is limit the amount of digestible carbohydrate we eat. Overall, the less digestible carbohydrate we consume, the less there is to convert to fat and store in fat tissue.

Both of these strategies will work to decrease fat storage. As an added benefit, it will also improve the body’s ability to access the fat stores, which helps improve insulin sensitivity. A positive outcome for type 2 diabetics.

Digestible Carbohydrate is an important concept to understand

Overall, as a type 2 diabetic, knowing how certain foods spike your blood sugar is important. However, knowing what happens to the digestible carbohydrate may be even more important to know.

Since we can eat foods that decrease (or limit) fat storage, we can impact our overall blood sugar. This will work to improve insulin sensitivity, so that we can control our blood sugar more naturally – instead of using medication to do it. Beyond all that, none of us like storing body fat – we don’t like the way too much of it makes us feel or look, but the negative impact it has on insulin sensitivity makes it worse.

Understanding this and acting accordingly will have a positive impact on your condition.

Type 2 Diabetics and the Disposition Index

When most of us think about type 2 diabetes, we think about several things: problems with blood sugar control, insulin sensitivity, difficulty in losing weight, struggling with exercise, etc… Most of us, however, rarely, if ever, think about an obscure term known as the disposition index.

It is so obscure, it doesn’t even have its own Wikipedia page!

While most of the things we think about regarding type 2 diabetes are part of the condition, the reality is they are just individual pieces of the same puzzle.

That one thing that encapsulates all of this is the disposition index.

Why Type 2 Diabetes Occurs

The typical progression from normal blood glucose control to type 2 diabetic goes something like this:

Over time, our insulin begins to lose sensitivity. This can be due to a number of factors but is typically the result of chronically elevated blood sugar (glucose) as a result of our diet. As our insulin loses sensitivity, our pancreas starts to secrete more insulin to deal with the elevated blood sugar. Somewhere during this progression, most people start gaining weight, typically when insulin first starts losing sensitivity.

Eventually, insulin struggles to reduce blood sugar so the pancreas secretes more insulin. At some point, our pancreas is unable to continue secreting more insulin. This is when people get diagnosed as type 2 diabetic. They go to the doctor, get a blood test and find their blood glucose is too high. They then go through an OGTT (Oral Glucose Tolerance Test) and get diagnosed as a type 2 diabetic because blood sugars are not reduced appropriately.

In the two paragraphs above, insulin and blood glucose were mentioned frequently. So it it understandable when these things are mentioned as part of the Type 2 Diabetes condition. Notice that we haven’t even mentioned disposition index.

There is a good reason for that because the disposition index encompasses something else we haven’t mentioned: the pancreatic beta cells.

Pancreatic Beta Cells and Insulin

Insulin is released from the pancreas; more specifically, it is released from the beta cells of the pancreas. When your blood sugar is under control and insulin sensitivity is high, everything functions normally.

You eat a meal or a snack, your blood sugar elevates, your pancreas senses this, the beta cells secrete insulin, insulin does its job by reducing blood sugar and then insulin goes back to normal levels.

This entire relationship can be described with a mathematical function in both normal blood glucose control and type 2 diabetics. This function is known as the disposition index. See figure below.


Source: Bergman et all, Diabetes, 2002, Figure 1, page S213.
Note: Red lines added.

The horizontal axis is insulin sensitivity and the vertical access is insulin secretion. What we can note from this figure is that as insulin sensitivity increases, insulin release decreases. We also note the opposite: As insulin sensitivity decreases, insulin release increases.

Based on research, we know the following: The work required by the pancreatic beta cells changes as insulin sensitivity changes – this can be seen by in the graph above by noting the increase in insulin release as we move left along the horizontal axis (insulin sensitivity).

As noted above (2nd italicized paragraph), at some point the pancreatic beta cells are unable to secrete more insulin in response to elevated blood sugar as insulin sensitivity decreases.

Note the two boxes in the graph above. We have zoomed in on them in the figure below. The two bottom numbers in the figure below in each of the boxes is 800 and represented by DI, which is the disposition index. So both have a disposition index of 800 but occupy different places on the function. How can this be?

The other numbers in the boxes give us the answer. “S” refers to insulin sensitivity and “AIR” refers to insulin release. The insulin release value in the left box is 2,000 pmol/l while it is 400 pmol/l in the right box. This means, for all practical purposes, that to achieve an optimal level of blood sugar control, when insulin sensitivity is 2.0 pmol/l (right box) we have to release 400 pmol/l of insulin. If insulin sensitivity decreases to 0.4 pmol/l, we have to release 2,000 pmol/l of insulin – a fivefold increase in insulin release.

What this means is that as insulin sensitivity decreases, the pancreatic beta cells have to do more work by secreting additional insulin to deal with the elevated blood sugar. The beta cells adapt to this additional work and over time, they reach an “insulin secretion limit.” This results in chronically elevated insulin and blood sugar, also known as type 2 diabetes.

But it is clear the dysfunction in pancreatic beta cells is the first domino to fall in this string of events.

So the main question is, what causes the beta cells to reach their limit? Why and/or how do they reach a point where they can no longer secrete insulin (or enough insulin)?

This is an active area of research, with new answers frequently. While there are answers to many questions, the precise mechanism has not been identified. And it may just be there are several factors that lead to this pancreatic beta cell dysfunction.

In our next post, we will cover some of the more promising areas of research. Included will be things you can do to increase the health of your pancreatic beta calls.

By implementing some of these suggestions, your insulin sensitivity will certainly change. This will also lead to an improvement in insulin release. Overall, this will lead to an improvement in your control of type 2 diabetes.

That’s something all of us want.

Can losing fat from the pancreas reverse type 2 diabetes?

Maybe!

This summary says it can.

The summary comes from this article, which paints a slightly different picture, but important nonetheless.

So what is going on?

Well, it is part truth and part sensational, attention-grabbing headlines.

Gastric Bypass, Insulin sensitivity and Type 2 Diabetes

In the actual study, the authors evaluated both type 2 diabetics and non-diabetics, matched for age, sex and weight, before and 8 weeks after gastric bypass surgery (laproscopic RYGB).

The results were interesting.

Both groups lost weight after surgery (not surprising) and both groups lost a significant amount of body fat (also not surprising). However, the type 2 diabetic group also lost a significant amount of pancreatic fat, which did not happen in the non-diabetic group. See figure below.

This led to significant improvements in all measures of insulin sensitivity for the type 2 diabetic group, which means a significant improvement in controlling type 2 diabetes. In other words, they improved.

It’s also likely why the authors of the summary had such a sensational headline.

Can you spot reduce visceral fat?

So what happened here?

The type 2 diabetic group had a higher level of pancreatic fat before surgery. This is internal fat, known as visceral fat. Subcutaneous fat is the fat right underneath your skin. It’s the fat you can pinch. Studies have repeatedly shown that visceral fat is more detrimental to your health than subcutaneous fat.

If you are type 2 diabetic, you might wonder if you can specifically reduce visceral fat and improve your insulin sensitivity. And based on the questions I’ve had, many of you are wondering this.

The answer is kind of.

You can do this through diet and exercise and probably by sleeping better and managing stress.

We will focus on exercise and diet.

Exercise, Type 2 Diabetics and Visceral Fat

Higher intensity exercise has repeatedly been shown to decrease visceral fat, whether type 2 diabetic or not. And, while both low and high-intensity exercise have been shown to also reduce subcutaneous fat, it is high intensity exercise that can do so more preferentially.

Given that the type 2 diabetics had higher amounts of visceral fat at the beginning of the study, exercise might be a plausible explanation for the significant reduction in pancreatic fat after surgery. It’s unlikely, though, since surgery can be rough and assessment was only 8 weeks after surgery.

Diet, Type 2 Diabetics and Visceral Fat

It is likely the significantly reduced caloric intake after surgery was the main reason for reduction in pancreatic fat. Prior to the surgery, the average weight of the type 2 diabetics was 266 pounds. Eight weeks after surgery it was 230 pounds. This is an average weight loss of 36 pounds or 4.5 pounds per week. And…of those 36 pounds of weight loss, 30 of them were fat, which means they were losing 3.75 pounds of fat per week.

To lose 4.5 pounds per week, you need a daily caloric deficit of 2,250 calories per day (going by the 3,500 calories per pound, which is questionable). That’s a HUGE caloric deficit!

Which brings us back to diet and visceral fat. A caloric deficit this large will lead to significant visceral fat reduction. And without surgery, I’m not sure anyone can subject themselves to a caloric deficit of this magnitude.

Outside of gastric bypass surgery, what can you do, at least nutritionally, to decrease visceral fat? The research is fairly clear on this. A diet that severely limits processed foods – particularly processed carbohydrates will help. A low-carb, high-fat diet (which may be the same thing) will also do the trick.

But it won’t work as fast as surgery.

So what does is all mean?

Well, the diabetes wasn’t reversed in this population but it was significantly improved. And it corresponded to a decrease in pancreatic fat. This most likely happened because of a massive reduction in caloric intake after gastric bypass surgery.

Outside of surgery, are there things you can do to preferentially target pancreatic or visceral fat? Yes!

If you are a type 2 diabetic you should consider two things: 1) a diet lower in processed carbohydrates and 2) work to improve your fitness level. Diets lower in processed carbohydrates (or low-carb, high-fat diets) have repeatedly been shown to reduce visceral fat (and subcutaneous fat too). Improving your fitness level through any means of physical activity so that you can perform higher intensity activity is also important. And at some point, you probably need to make sure you are getting enough sleep and managing stress.

These two things will accomplish the same as the surgery, just not as quickly or severe.