Sweet Science

Insulin Sensitivity.

The newest term in a long line of humbling information teaching me that no matter how much I learn, I still am a nobody and the body is really freaking complicated.

Before continuing, let's clear something up. I am not a chemist nor am I a nutritionist. I took gen chem and half of organic chem in college, and have biochemists in my family....but I am not a chemist and I don't remember much. I know jussst enough to see a molecule, read about it, and kind of get what they're saying.

So here's my just enough knowledge to translate into real, practical information. I just have the chemical structures because I like them and am a visual learner.

Now a lot of talk about sugar before I talk about insulin, the real topic at hand. I'll get there eventually. There is SO MUCH more to this topic and I went down many rabbit holes writing this blog. This is not called Scientific Journal, this is called Map to Fitness. This is my futile attempt at understanding the complex world of nutrition and fitness. I'd like to think there's decent information here, and by explaining concepts I am forced to understand them better. Also, there are many things that end in "ose," the suffix associated with sugar, that I do not discuss. I'll talk a little about simple sugars vs. complex carbs and really for this blog, that's enough for now.

Enough disclaimers.

We have all heard we need to avoid high fructose corn syrup!! But why? And are all forms of fructose bad? Doesn't the body need sugar to operate?

Correct. I knew the brain operates on "sugar" to function, and the body will create molecules from other sources in order to survive when necessary. This is the basic premise of the Ketogenic Diet, which insists on depriving people of all carbs in order to undergo ketogenesis, which in very simple terms uses fat to create ketones to compensate (NOTE- I tried figuring out if the ketones then undergo reactions to become glucose and couldn't find anything easy to understand. It doesn't really matter for the purpose of this blog). I am not a fan of that diet, at all, but that is a post for another day.

I digress. Glucose is really a form of sugar that the body likes and uses well. It is used for immediate energy, it feeds the brain, it travels in our blood (what we mean when we talk about blood sugar levels), it can be stored in muscles, and it gets stored in the liver as glycogen aka energy reserves. Like anything else, too much of a good thing is a bad thing, and you don't want that getting too high either. That's when you start storing it as fat. Fat, from an evolutionary perspective, is a great storage system; if and when times get hard and food is scarce, your body can use fat for energy! This is what happens when we are in a caloric deficit and how we lose weight. So, glucose is used efficiently for energy and energy storage, but we only need reasonable amounts.

As you can see in the structures to the left, fructose looks a little different. If you're unfamiliar with ochem, don't' worry.  In very unscientific terms, there is a ring of 6 things in glucose, and a ring of 5 things in fructose. The carbon that is not being used in the ring in fructose is pulled out and adds a little extra bulk on the outside. The molecular formulas are the same, C6H12O6, but the structures are different. This can have a huge impact on how the body processes these molecules. Apparently, unlike glucose, fructose is only processed in the liver and has been found to be much more lipogenic (fat producing). From what I've been reading, it does not trigger insulin (it does not need insulin to be processed),  and has been shown to lead to insulin resistance. More on that later.  Fructose also appears to not produce leptin, which is a hormone telling your brain that you're full and fed. Leptin is associated with energy expenditure and balance, and some studies suggest that chronic fructose exposure may lead to leptin resistance. In this case, your body has high levels of a hormone saying hey, I'm full, but the brain doesn't process it and so you eat more.

Sucrose, aka table sugar, in simple terms consists of these two molecules combined (with one less Oxygen). When you eat sugar your body breaks this molecule down into the two components. Glucose is processed and used for energy, as described above, and any excess of glucose and fructose is then essentially stored as fat. So when people say they're having healthy sugar because it's some raw "natural sugar," okay. But you're still essentially getting fructose!


Now that we've discussed the molecules just a little bit, we can explore something called the glycemic index (GI) of foods. Essentially, this refers to how food impacts blood glucose levels. High GI foods enter the bloodstream very rapidly because they tend to be simpler in structure and result in a rapid insulin spike. Remember how sucrose is broken down to glucose and fructose? It's that type of concept, only other molecules are much larger, involve more complex processes, break down at different times in the digestive process, etc. etc. Insulin can help shuffle glucose into muscle and be used for immediate energy, but it can also help things store as fat easier. GI is typically discussed in terms of <55 is low, Moderate is 50-70, and High is >70.

Looking at a chart of GI is not sufficient, however. I won't get into how they label GI foods, but suffice to say it's based on a certain amount of each food, not the actual serving size. Glycemic Load (GL), on the other hand, evaluates the effect based on actual portions. This changes the story dramatically. GL is 0-10 Low, 11-19 Moderate, and 20+ high. While both are useful in their way, I do not currently know why GI would ever be discussed without GL. For example, according to a chart from Harvard (cited below),  watermelon may have a GI of 72 (High!), but a GL of 4 (Low). The chart below shows this nicely. There's a lot of added complexity too, depending on what you eat in your meal. If you eat a high GI food, but it's paired with something low GI (i.e. fibrous foods), it can slow digestion and the rate/amount of glucose in the blood.


[[[Harvard has a user-friendly chart for some more common foods on their site (Click here). If you want to see a fairly exhaustive list, the above link's information is based on this 2008 study by Fiona S. Atkinson, RD, Kaye Foster-Powell, RD, and Jennie C. Brand-Miller, Ph.D. (Scroll down to the supplementary information).]]]

Okay. Now that we've talked about all of that, I get to my point!!!

When we eat carbs, our blood sugar rises. Insulin is a hormone released by the pancreas in response. Insulin then strolls around the blood telling other cells to pick up the glucose. Cells can be more or less responsive to insulin. If less, the pancreas starts shooting out more insulin and over time this can hurt the pancreas and result in high levels of blood sugar and insulin. Eventually, the pancreas can be damaged and blood sugar rises even more.

Increased fat intake/development can contribute significantly to this. I like to imagine fat as greedy, mafia like cells that steal the glucose before other cells get a chance. Biochemically this is probably not correct, but the personification works for me. There's more to it, but that's enough for now. Thin people can be insulin resistant too, as other factors can contribute like fructose intake (sound familiar?), inflammation, inactivity, and of course, genetics. Inulin resistance causes a whole host of problems.

Insulin sensitivity refers to the extent to which your body uses glucose "well." So, million dollar question, how do we improve our sensitivity?

REDUCE SUGAR: If you didn't get that from this post, I have failed you.

LOW GI/GL FOODS: Hopefully you saw this one coming too.

TIMING: Post-workouts seems to be when we're most insulin sensitive (see addendum on my Best News Ever post)

LOSE FAT: If there are less mafia-like visceral fat cells to nab the glucose, more can be used for muscle storage!

EXERCISE: Not only does exercise help you lose weight directly, it also does something with the cell receptors (i.e. marathon runners' insulin use is so well used that blood sugar is quickly used and the pancreas reduces insulin release).

OMEGA 3's: nothing to see here. Look at any "how to" in the health world and you'll see these.

SLEEP/STRESS REDUCTION: look at my previous posts. I don't know about this specifically, but it sure makes sense. As a clinical psychologist in training, I could go on and on about how these two affect physical health and well-being.

INTERMITTENT FASTING: I guess. I don't know anything about it. But Dr. Jim Stoppani said so in a recent post I saw on bodyspace and other articles on insulin sensitivity have suggested the same thing. This is the article that did me in for this whole freaking post. One thing led to another... Here's Jim's guide on IF

I saw some other things too: magnesium, donating blood regularly, stop smoking, and eating "whole" foods (source), and chromium potentially helps especially insulin resistant populations.

And there you have it. Insulin Sensitivity. Direct health benefits. Reducing risk for many medical concerns. Maximizing the use of your caloric intake.