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Toolbox: Hold the Fat on the Bike
toolbox-feed650 As the trend towards eating more real foods on the bike grows, I hear more and more questions about eating raw nuts, bars made with bacon and cheese or nut butters while racing or training. Let’s look to clarify cycling nutrition and why the average bike racer (not extreme ultra endurance events lasting over 15 hours) should not rely on fats as fuel during and immediately prior to competition.

The body uses fatty acids as fuel mostly during low to moderate intensity cycling under 70% of VO2 Max. At almost all times the body is using both carbohydrates and fat as fuel. Just because the body uses fat as fuel, it doesn’t mean fat is a good fuel choice to consume during racing and training.

Most average racers are competing anywhere from 1 to 5 hours in duration. Events of this duration will include a lot of intensity and high threshold riding. The higher the intensity of the race, the more you will rely on exogenous carbohydrates or glycogen as fuel. The percentage of fat used will be dependent on the intensity and duration of the race.

For bike races and hard training, the fuel intake of choice should be high density carbohydrate foods, low in fat and protein. So why hold the fat. It really comes down to gastric emptying time, avoiding GI upset and the ability of the body to utilize fat as fuel during high intensity exercise.

When you eat a meal before a race or training ride, it’s important to give yourself the time to digest it. If you want to be able to use that food as energy for the race in question, you need time to absorb it too. What you don’t want to do is set up a scenario where your muscles are competing with your digestive tract for your body’s resources – namely for blood flow.

Paris-Nice stage-4

When you start exercising, blood is required for your working muscles. Blood is also required for digestion. If you start exercising while you have an undigested meal in your gut, you now have to split that blood between muscles and digestion. You are left with a scenario where both jobs will get done, just not as effectively as they could be, leaving racers with GI upset and heavy legs.

Depending on what your meal consists of, the time to digest and absorb it will differ. For example a meal high in fat, fiber and protein will take longer to digest and absorb than a high carbohydrate dense meal with low fat, fiber and protein. Fat and protein have slower gastric emptying times than carbohydrates.

For a typical pre-race breakfast (events over 90 minutes in duration) most cyclists want to give themselves 3-4 hours to digest and focus on 150+ grams of carbohydrates. Meals should be lower in fat and moderate in protein. After 3-4 hours most of the meal will be digested.

As cyclists get closer to race time, let’s say an hour out, the focus should narrow towards solely high carbohydrate dense foods, low in fiber, protein and fat. Examples being potatoes, rice bars, sports drinks, bread and jelly, chews etc.
Remember that fat and protein have slow gastric emptying times and you don’t want to start that criterium with a ham and cheese sandwich competing for that much needed blood flow to your muscles. Not to mention many riders will regurgitate that undigested food during a race. Not ideal or enjoyable.

During your race or training, the same rules apply. Eating raw salted almonds, bread with almond butter, bars with bacon and cheese or other high fat foods, will result in slower gastric emptying. That means even if you eat them in combination with a sports drink or chews, the entire meal gets held up. Now your much needed carbohydrates will take longer to get to the working muscles. Also you are creating the competition for blood again, potentially causing indigestion and heavy legs.

For athletes who are convinced that they feel so much better on their morning 90 minute hammer sessions due to their high fat breakfast or that raw coconut they just ate, remember this; It takes about 2 hours for long chain triglycerides to even get to your intestines, even if they were to be used as an energy source. The reality is for any ride under 2 hours, even if fat didn’t slow your gastric emptying rate, it would still be quite useless.

Fat is the last nutrient to get processed. Most fat digestion occurs in the small intestine with minimal digestion occurring in part to enzymes in saliva and in the stomach. This is one of the main reasons we don’t consume fats while racing. The digestion really is slow.

The bottom line is at almost all times you are using carbohydrates and fat as fuel while cycling. The higher the intensity the more you rely on carbohydrates as fuel, the lower the intensity, the larger percentage of fat you will use as fuel. Although fats are a great source of energy, their slow gastric emptying and inability to be used at very high intensities, makes them a poor fuel of choice while cycling.

The ideal fuel choice while cycling a typical distance bike race is still high density carbohydrate foods, low in fat and fiber.

It’s important to note that the rules of every day health do not apply to on bike nutrition. This can be difficult for some cyclists who are extremely health conscious off the bike.

A typical off the bike meal is ideal when it empties the stomach slowly, has some fat, fiber, protein and carbohydrates. During the day we want slow blood sugar release and we want to feel full for a long time, controlling our hunger and energy levels.

On the bike, we have a different scenario. It’s important to differentiate the two for optimal performance and GI comfort. Separate “performance nutrition” and “daily nutrition” in your mind. Be willing to let go of the “healthy” foods in order to gain a performance advantage. Once you are off the bike, get right back to your healthy habits and you will be right on track!

But remember, while racing “hold the fat”.

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