Why protein and fat during an endurance event can keep you from performing your best

In order to achieve optimum performance in any endurance sport you need to maximize oxygen delivery to the working muscles. What you eat plays a significant role.

the problem with fat and protein during your event

Fats and proteins have to go through a full digestive process, thus taking oxygen away from your working muscles.


If you remember the Lance Armstrong scandal, it was all about blood doping. By illegally increasing the amount of oxygen in your blood, more oxygen is then provided to the muscles. The more oxygen you have available the better you will perform, period. Likewise, if you reduce the available oxygen to the muscles your performance will suffer.

When your are training or competing, your body is amazingly adaptive and it does everything it can to help you out. One way it does this is by drawing blood from parts of your body that don’t need it at that time so that it can route more blood (and therefor oxygen) out to the working muscles. A large user of blood is your stomach and gastointestinal (GI) tract. As long as you are not digesting anything then your body can draw on this blood supply.

The beauty of liquid carb calories (like e-Gel and e-Fuel) is that they are rapidly – the fluids by osmosis and the carbohydrates are transported by energy transporters (SGLT1 and SGLT5). However, when you consume anything with fat or protein, these ingredients must go through a slower digestive process. This means that your body has to route blood back to the stomach and GI for the digestive process, thus taking blood and oxygen away from the working muscles.

You may not even know this is happening, but if you are trying to set a personal best, run a qualifying time, etc., consuming something that takes away from your performance, even a little bit, should be avoid if possible. Many people like to use what they call real food, which typically means foods with fat and or protein. Everyone needs to use what works best for their own body, but we’re confident that if you do an honest test for yourself, you will find that you perform better with liquid carb calories.

gels cause stomach issues?

If you avoid using gels because they have caused stomach issues, it’s typically because one or more of these reasons:

  • Using gel with something other than water. The combined solution in your gut can be too concentrated, thus delaying absorption and potentially bothering your stomach.
  • Not staying properly hydrated. If you get behind on your water intake with gels they will not be properly diluted and you’ll get the same result as above – delayed absorption and possible stomach issues.
  • Eating other foods along with your gel. This is what we call ending up with a “soup” in your stomach. It’s amazing how many people we talk to that tell us that they can’t use gels because they bother their stomach, but then they tell us that they are also eating fruit, energy bars, etc. along with the gel. The problem isn’t the gel, it’s the soup!
  • Using a gel that has protein and/or fat. Most gels don’t, but some do so be sure to know what’s in your gel!

If you use a good carbohydrate based gel properly you should never have issues. And the beauty of e-Gel is that it has all the electrolytes you should need right in the gel so you don’t have to worry about electrolyte supplements. Just use e-Gel and water – it’s that easy!

prefer drinks?

Using a good sports drink (low in sugar and high on complex carbs) gives you the same benefits as using gel and water. Use which ever you prefer! Many runners and other athletes that have to worry about carrying water weight tend to opt for gels (and then get water along the way). For the rest of the world that thinks gels are weird, drinks are the way to go!

note on ultra events

When you are competing in ultra events all the rules change a bit. Because you are out so long and going at a lower intensity level, you can and may want to incorporate fat and/or protein in your nutrition plan. You still may experience GI issues due to slow digestion, so it’s important to find out what works best for you. Always remember to train the way you’re going to race!


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