Calories or Carbs for Cycling: Which Is More Important? A Coach’s View

By Coach John Hughes

Dear Reader, remember we are all an experiment of one in nutrition. As you read what follows consider if it makes sense and applies to you.

In an earlier column Calories or Carbs?   Mike E. asked, “I was wondering which is more important in cycling – calories or carbs. I’m a type 2 diabetic and have to watch my carbs.”

Mike, you’re asking a terrific question, which relates to all cyclists. Calories from carbs are your most important fuel. You can eat carbs without affecting your diabetes. The issue isn’t carbs in general but how specific carbs affect your body.

Cyclists often hear different claims about nutrition, which are myths, e.g., 

1. A high fat low carb (Keto) diet is better. The American College of Sports Medicine says that a high fat / low carb diet can be as good as a higher carb diet at moderate intensities of exercise; however, the high fat / low carb diet can’t support intense exercise.
   
2. Simple carbs are bad. This assertion is based on the fact that simple carbs include processed and refined sugars such as candy, table sugar, syrups, and soft drinks, which have little or no nutritional value. However, simple carbs are found in foods such as milk, fruits and vegetables, which are very healthy.
   
3. Simple carbs cause your blood sugar to spike and then crash. This is correct in your daily diet; however, exercise lowers high blood sugar by making the cells respond more effectively to insulin to drive sugar from the bloodstream into muscles.

You can read more in this column:  Anti-Aging: 7 Nutrition Myths

Diabetes

According to the Mayo Clinic,  “Diabetes mellitus refers to a group of diseases that affect how the body uses blood sugar (glucose). Glucose is an important source of energy for the cells that make up the muscles and tissues. It’s also the brain’s main source of fuel.

“The main cause of diabetes varies by type. But no matter what type of diabetes you have, it can lead to excess sugar in the blood. Too much sugar in the blood can lead to serious health problems.”

Healthy Diet

The Mayo Clinic recommends a diet of healthy carbohydrates. “During digestion, sugars and starches break down into blood glucose. Sugars also are known as simple carbohydrates, and starches also are known as complex carbohydrates. Focus on healthy carbohydrates, such as:

• Fruits.
• Vegetables.
• Whole grains.
• Legumes, such as beans and peas.
• Low-fat dairy products, such as milk and cheese.

“Avoid less healthy carbohydrates, such as foods or drinks with added fats, sugars and sodium.” 

Glycemic Index

The glycemic index (GI) measures the rate at which your blood sugar rises after eating something. White bread and pure glucose have GIs of 100. 

• High GI 70-100
• Moderate GI 40-70
• Low GI <40

Here are some examples:

Examples of Bars, Cookies and Candies

Food	Glycemic Index
Oatmeal Cookie, average	79
Pop-Tarts, Chocolate	70
New Potatoes, boiled	70
Granola Bar, average	60
Vanilla Ice Cream	60
PowerBar, Chocolate	58
Clif Bar, Chocolate Brownie	57
Snickers Bar	57

Note that boiled potatoes have a GI of 70, higher than ice cream’s GI of 60.

Gels

Reference works don’t give the GI of sports gels; however, the ingredients are indicative of the GIs

• GU — 70 to 80% maltodextrin and 20 to 30 %fructose.
• HammerGel — primarily maltodextrin and fructose 
• PowerGel — primarily maltodextrin and fructose

Maltodextrin has a very high GI and fructose a low GI. The proportions of maltodextrin and fructose determine the GI. Because maltodextrin is the primary ingredient, these gels have a pretty high GI.

Examples of Drinks

Drink	Glycemic Index
GatorLode	100
Gatorade	89
HEED	High GI per Hammer Nutrition
Skratch	Probably high *
Powerade	65
Cytomax	62
Coca Cola	53
Apple Juice	44
Orange Juice	46

* Skratch’s primary carbs are cane sugar and dextrose, which have high GIs

Note that Gatorade, HEED and Skratch have much higher GIs than Coke and fruit juices.

For more information on the glycemic index of specific products here are two sources:

• The Glycemic Index website
• Mendosa.com GI List

The GI varies significantly depending on the exact type of food: one source lists 45 different GI values for different types of rice, ranging from the 30s to the 80s! The GI of an item of food is tested when the food is eaten in isolation; however, that’s not how we eat. Foods with high GIs are often more refined and have fewer vitamins and minerals. For example, white rice has a higher GI than brown rice, which is healthier. 

Daily Nutrition

High GI foods can cause blood sugar to rise and fall significantly if you aren’t exercising at the time. In general, you should eat low- to moderate-GI foods during the day and before a ride; however, the quality of the foods is more important than the GI.

Riding Nutrition

Your muscles burn a combination of fat and glucose. Your body can store approximately 1800 calories worth of glycogen in your liver and muscles. The glycogen comes from carbohydrates. Through endurance training you can increase your ability to store glycogen by 20 to 50%. The glycogen is metabolized to glucose to fuel your muscles and your brain.

If you don’t eat carbs, you can exhaust your glycogen stores during a multi-hour ride. At an endurance pace you’re metabolizing more fat than glucose. Endurance training increases the proportion of fat and reduces the proportion of glucose your muscles metabolize at a moderate pace, which saves glycogen. Note that this doesn’t automatically result in weight loss; that is a function of calories in and calories out.

On the bike the total calories of carbohydrates consumed per hour is generally more important than the GI of any specific carbohydrate.

American College of Sports Medicine Recommendation:

Consume 25 to 60 grams of carbs (1 to 2 ounces or 100 to 240 calories) per hour after the first hour of exercise. This is sufficient for several hours of exercise. If you are riding for three hours or more start eating carbs in the first hour. If you are relatively small or exercising lightly 25 grams / hour is enough. If you are larger or riding at a moderate to fast pace eat up to 60 grams / hour.

If you stick to a higher fat / lower carb diet your body will adapt to fuel itself without a lot of carbs; however, according to the ACSM this provide no performance advantage.

Frequency of Eating

When your blood sugar crashes you bonk. This is not a result of consuming foods with a high GI on the bike, but of not eating enough and not eating frequently. Eat some carbs every 10 to 15 minutes. You can read more in this column:  How to avoid bonking.

Intensity of Riding

GI becomes more important the harder you ride. Higher GI foods are converted to glucose faster, which is what you need on a hard climb or riding with a fast bunch.

Experiment of one

What matters most is what tastes good to you and what sits well in your stomach.

My eBooks:

Nutrition for 100K and Beyond.

The principles and recommendations for eating before, during and after a ride apply to all roadies. These are explained in Nutrition for 100K and Beyond. Although written for roadies riding 100K and farther, all roadies can learn from it. I show you how to approximate how many calories per hour you burn. I compare the nutritional value of bars, cookies, candy and real food. I also discuss hydration and electrolytes. I conclude by discussing what you should eat every day to ride your best. My 17-page Nutrition for 100K and Beyond is just $4.99.

Eating and Drinking Like the Pros

My eBook Eating and Drinking Like the Pros describes in detail what they eat for breakfast, during a race, after the race for recovery and for dinner. During a race they consume some sports bars, gels and drinks; however, most of their calories come from real food. The eBook includes a dozen recipes to make your own riding nutrition, each of which I tested with clients and friends. The 15-page Eating and Drinking Like the Pros is just $4.99.

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Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written over 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.