Yes, Sugar!

Lorenzo Wimmer

July 01, 2016

diets physiology sugar

Let’s touch a little on this subject without going to great lengths for fear of losing you halfway through.

First, let’s talk about the many names that sugar and other starches are disguised as in our foods today, and what it means to our body. There are approximately 57 different names given to different types of sugars that we come in contact with in various processed foods every day. Marketing companies go to great lengths to design new names to disguise one product… sugar. (My intent is not to go on a sugar bashing rant, merely providing awareness that your television will not tell you).

Some of the names you may run across in the ingredient list in some of the foods you buy at the store might be:

  • Agave nectar
  • Evaporated cane juice
  • Invert sugar
  • Sucrose
  • Barley malt extract
  • Corn syrup
  • Fructose
  • High fructose corn syrup (HFCS)
  • Maple syrup
  • Blackstrap molasses
  • Turbinado sugar
  • Raw sugar
  • Galactose
  • Lactose
  • Caster sugar
  • Palm sugar
  • Ethyl maltol
  • Fruit juice concentrate

And so on… I think you get the picture. Out of all of those names, what do you think your body sees when it sees any of those?

Yes, Sugar!

The body reacts nearly the same to all of the sugars listed above. The body does not care if they are organic or not… The chemical structure is what it recognizes. High fructose corn syrup has become quite the dirty household word of late as we have become concerned about how much sugar is in all of our food. Thus, ushering in the widely accepted and embraced, “organic agave nectar”. HFCS contains about 55% fructose. Of course we don’t want all of that sugar in our diet, so we did our bodies a favor by buying organic agave nectar, which contains a minimum of 75% fructose. Now that didn’t help much, did it? (excess amounts of sugar are converted to fat in the liver, a process known as novo lipogenesis… your body makes fat from sugar).

You are very well-trained ultra athletes, having read reams of information over the years on how to fuel your endeavors. You all know what works best for you, as we are all different, different metabolisms, different levels of fitness, different ages… but some things remain the same… what our bodies are predisposed to do with the foods we consume to fuel our run.

Many of our energy gels that we take on our trail runs contain fructose, agave nectar and maltodextrin. (Maltodextrin is a processed food, most commonly derived from corn, but we’ll get into that at a different time).

The fructose contained in the energy gels cannot replace the muscle glycogen that you are burning at a high rate while you are running, (Once your muscle glycogen is spent, your body must shift to an alternate fuel for you to continue your run, i.e. fat). The fructose must be first metabolized by the liver before the body can utilize it as fuel. That process is not immediate… There are several changes that your liver must make to fructose to send it back out into your bloodstream to be converted to glycogen and then to glucose. Ultimately, the glucose is burned as fuel. (If you want an immediate source of energy, you must consume the sugar in the form of dextrose).

Glycogen, our primary arsenal of fuel, is stored glucose (dextrose). This is the first place our body will look for fuel to do the more physical efforts of keeping specific body systems functioning, like our brain, kidney and red blood cells. This glycogen is primarily stored in the liver and your muscles. Of those two organs, only the liver will share with other organs, but not so for muscle glycogen. It is stingy… muscle glycogen will only supply energy to muscles… and once it is gone, it will take time to replenish.

Osmolality: Other sugars that we consume on our training runs or long distance events are in the form of sports drinks and the like. At an aid station we have all knocked down a good pint or two of Gatorade to quench our thirst and replace our electrolytes. Do you remember that queasy feeling you got about 15 minutes after consuming it? Most probably it was from the high sugar concentration in the Gatorade that gave you an upset stomach, and possibly G.I. distress somewhere down the trail.

It is not uncommon for us to think of our stomach as a gas tank, a solid receptacle for food and drink. However this is not exactly the case…our stomach is a semi permeable membrane where fluid not only moves through it, but passes back-and-forth through the walls of the stomach as well.

Our bodies like things to be equal, a state known as homeostasis – fluids with the same osmolality, (electrolyte-sugar-water balance) inside and outside the gut… It does not particularly care for the high concentration of sugar solution in your stomach, so it scavenges fluid from your body cavity and brings it into your stomach so the concentration of fluids on both sides of the stomach are nearly equal. This has now caused two problems: in your effort to rehydrate yourself, you have actually dehydrated yourself by bringing fluid from your body cavity into your stomach. Your second problem is, you have an excess of fluid in your digestive system now, all which must go somewhere, sometime soon (oops). There are sodium-glucose transporter proteins that inhabit our intestines. They help to quickly transport sodium and glucose if they are in the correct concentrations. These two substances are precisely what we are trying to replenish. The approximate concentration of sugars in electrolyte sports drinks that are more agreeable with your body is about 4%, (4g sugar/liter). For example, Gatorade’s G2 is closer to 4%, while still rehydrating you adequately and replenishes the much needed electrolytes as well.

This is a good case for “a little is good, a lot is not better.”

That should do it for our first attempt at trying to hold your attention. I hope you got this far. Next month’s topic we will discuss fats and their importance and role in endurance nutrition and performance.

I am happy to contribute to our club anyway I can, and I hope you have found this information useful. I will gratefully take suggestions on any other topics of food and nutrition that you would like to discuss. You are welcome to comment on the post below.

Over Hydration