This is Your Body on Sugar

I want to talk about something that I have hinted at in a couple past articles: the way burning sugar affects your energy levels and health.

It is relatively common knowledge that when you eat sugar, you’re going to have an energy spike. As we discussed in the last article, the reason for this spike in energy is the swift rise in blood glucose that comes when you eat simple sugars/carbohydrates.

Please note: this kind of spike is not only limited to pure sugar. Highly processed carbohydrates, such as white flour, cause this same kind of spike. Basically, the more refined the carbohydrate, the quicker the digestion process, and the quicker the broken down digested carbohydrate (i.e. glucose) enters the bloodstream.

What prevents this spike? In carbohydrate rich foods, its fiber, which we touched on previously and will go into in the future. Additionally, eating protein and fat at the same time as eating carbohydrate slows the digestion process.

But don’t take that to mean you can go eat a ton of full fat ice cream due to the fat slowing the digestion process. It doesn’t work that way, unfortunately.

To illustrate the issues with the blood glucose spikes we discussed in the last post, look at the graph below.


This is a crude illustration of the way blood glucose and insulin levels change following a meal. The solid lines represent the blood glucose and insulin response following a meal filled with simple carbohydrates (i.e. sugar), while the dotted lines indicate response following a meal of complex carbohydrates. As you can see, the spike in both blood glucose and insulin is significantly larger following the simple carbohydrate meal.

I want to point your attention to what happens to your blood glucose following a meal high in simple carbohydrates. Not only does it spike up extremely quickly, it also dives extremely quickly. This is because the body, sensing the high blood glucose load, secretes a large amount of insulin. With all this insulin around, the blood glucose is disposed of (i.e. stored in tissues) very quickly. So quickly, in fact, that the blood glucose dips below the normal level.

This is the point where people have symptoms that may be classified as “hangry”. These include extreme hunger, fatigue, nausea, moodiness, irritability, etc. If you’ve seen any of the recent Snickers commercials, you probably have an idea what I’m talking about. The body has reached a point of hypoglycemia, or low blood glucose levels. Basically the body needs more fuel, hence these symptoms. I would argue a Snickers is not the best choice to combat this, as we’ll get to below.

Hypoglycemia, if it gets to extreme levels,  it is a potentially deadly condition. Though it rarely ever gets to that point (the body has mechanisms for preventing that level of hypoglycemia). However, these symptoms of moderate hypoglycemia are significant and can range from annoying to debilitating.

Part of my own personal difficulties with food was tied with this set of symptoms. I would be ravenously hungry every 3 hours, while also incredibly tired and fatigued after a meal. My usual meal was something along the lines of a supposedly “healthy” PB&J sandwich with pretzels and a banana – i.e. full of simple, easily digestible, carbohydrates. These spikes and crashes were truly debilitating for me, as I talked about previously here.

So why does “hangriness” happen? It all has to do with the mechanism of insulin. Insulin (released from the pancreas in response to food/glucose intake) is a very important hormone in the body. It also has a very complicated method of action. I could spend many articles going into the minutiae of insulin signalling (and maybe I will in the future), but this article is about the basic overreaching concepts, which if you understand, you will have a much better time adjusting your diet and health accordingly.

I want to point you to the diagram below related to insulin signalling in the cell and how it helps clear blood glucose.


To summarize, when insulin is released into the bloodstream, its job is to help move glucose out of the blood and into the cells, where it can be used for energy and storage. The way this happens is  insulin binds to its receptor on the cell surface, activating a chain of events leading to the activation of glucose transporting molecules. These molecules allow the cell to take in glucose.

From there, depending on the cell type, the glucose is converted into various other chemicals. For all body cells, glucose can be used for immediate energy production through the production of pyruvate (this is basic cell metabolism, taking you back to all those fond memories of high school biology).

When there is a great deal of glucose available (more than is necessary for short-term cellular energy) the body can store energy in a few different places. We went over this a bit in the last article, and I’ll bring back my cupcake diagram below from the last post. Glucose can be converted either to glycogen in the muscle and liver (though there is limited storage space) or to fat in adipose tissue (pretty much unlimited storage capacity).


The basic idea here is this: your body doesn’t want high levels of glucose in the blood. Its toxic, especially long-term, as you can see in diabetics who develop peripheral neuropathy, retinopathy, and other issues. It makes sense for the body, especially with the high blood glucose levels seen after a high-sugar meal, to put away this glucose in storage for use later. This is the whole point of adipose tissue. It provides a source of energy to be used when food is not available.

Ideally, when the body uses all the energy it obtains from a meal (or stores it), it would be able to access its wealth of energy stored in fat tissue.

But for many, this does not happen.

Why is this the case? There is a key point here not shown in the diagram. Insulin, especially in high doses, turns off the body’s ability to access fat stores to burn fat for energy (need facts/sources). Basically, in the body’s attempt to store glucose, it locks up the fat tissue from providing energy for the body.

While it makes sense that the body wants to normalize its blood glucose levels, especially with such high levels after high-sugar meals, it comes with a price.

Basically, what this means is that when you eat a sugary or highly processed meal, your body releases a large amount of insulin, quickly storing glucose away as fat. At the same time, the insulin locks up your fat stores, and this effect lasts some time. So when all the glucose is used up or put away, fat is still locked down, and your body has nowhere to look for energy except from more food.

The result: hangry. Those symptoms are your body’s panic signals saying it needs more fuel.

But the way most people get more fuel is to eat more sugar/simple carbs (i.e. Snickers), because that is what the body feels it needs to get out of hypoglycemia.

This leads to a yo-yo effect: spikes and dips in the blood glucose and insulin levels that lead to fat tissue generation without burning of the stored energy. This turns into obesity, insulin resistance, and chronic disease.

So how can you prevent this kind of downward spiral? Through complex carbohydrates and other lower-carbohydrate foods. The goal is to have slow rise in blood glucose levels, and therefore less insulin secretion (see the dotted lines in the first graph above). This kind of stability prevents significant adipose-tissue lock-down by large insulin spikes and allows an easier transition to fat-burning mode.

A quick note: this is a very simplified version of sugar and insulin signalling effects, but it is stuff worth understanding. Next time you happen to eat a sugary snack, look at how you feel a couple hours later. You’ll likely feel groggy, moody, or very hungry. The idea here is to understand how what you eat affects how you feel, as well as your long-term health.

Next time: a look at complex carbohydrates, and why they’re more complicated than the simple idea of “whole grains”

About the Author

Chris Goodrich, MD