Quick Guide to Carbohydrates
This article is the third article of a three part series about nutrition. Over the last two weeks, we discussed fats and protein and this week will dig into the importance & sources of carbohydrates for health, wellness and performance. Before we look into carbohydrates, I want you to have a clear understanding that proteins (specifically amino acids), vitamins, minerals and essential fats are predominantly building materials. Carbohydrates need to be thought of primarily as a source for fuel (i.e. the generation of energy).
What is a Carbohydrate?
A carbohydrate by definition is: any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose. They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body. The key words are “broken down to release energy”.
According to Harvard University, here is a breakdown of the “good” and “bad” carbohydrate sources:
- Healthiest sources of carbohydrates: unprocessed or minimally processed whole grains, vegetables, fruits and beans—promote good health by delivering vitamins, minerals, fiber, and a host of important phytonutrients.
- Unhealthier sources of carbohydrates include: white bread, pastries, sodas, and other highly processed or refined foods. These items contain easily digested carbohydrates that may contribute to weight gain, interfere with weight loss, and promote diabetes and heart disease.
The Importance of Carbohydrates & the Metabolism of Fat
The average individual has enough stored fat to fuel exercise for a very long time (the exact duration is an ongoing debate amongst exercise physiologists); however, you cannot burn fat without the presence of carbohydrates. With this in mind, you have to think about balance: too much fat or carbohydrates creates problems when it comes to optimum energy levels. Because of the negative media hype and the lack of knowledge, many individuals are avoiding too much (high quality) fat and eating too may refined carbohydrates and simple sugars. Ironically, this combination reduces the body’s ability to metabolize fat properly & an insulin burst which causes blood sugar levels to drop, both of which negatively affects muscular endurance.
Carbohydrates & Insulin Response
When you consume carbohydrates, your pancreas produces insulin, which ultimately causes your blood sugar to drop. Insulin does its job by sending blood sugar to the cells both in the liver and the muscles where it is stored in the form of glycogen. Ironically, insulin converts approximately 40% of your carbohydrates to fat for storage. For this reason alone, to reduce your body fat levels, you need to moderate your insulin response to the carbohydrates that you are eating.
Strive to eliminate all simple sugars from your daily food choices (except during & post exercise: see below). A simple rule of thumb is to eat only fresh, raw vegetables and fruit. These items are low glycemic (meaning low insulin burst) and loaded with vitamins, minerals and water.
Where Sugar is Stored & Function
Liver: stored sugar in the liver feeds the brain; low glycogen storages in the liver or low blood sugar levels will result in mental fatigue, the inability to focus and lack of concentration.
Muscles: stored sugar in your muscles fuel your training & racing; the higher the intensity, the quicker you deplete your muscle storages. Low muscle glycogen storages or low blood sugar levels will result in muscular fatigue & reduced endurance.
Which provides energy quicker – stored glycogen or glucose in the blood?
The key to optimum energy levels is the rate at which your body can convert sugar to energy. Your body can convert stored sugar (from the liver and muscles) at a much quicker rate than carbohydrates that have been ingested.
Blood glucose (converted from the food you have consumed) has to be chemically converted through a process researchers call phosphorylation. This is the conversion of glucose by adding phosphate; this conversion is completed by an enzyme called hexokinase. The enzyme hexokinase is the limiting variable in the body’s conversion of blood glucose.
Please don’t get lost in the terminology, but rather recognize that it is better to be consistent with your daily eating and snacking to create proper levels of stored sugar PRIOR to training & racing.
Carbohydrates Prior to Exercise – more than just a source of energy!
Carbohydrates consumed during snacks and complete meals in the form of raw fruits and vegetables, provide the body with a bundle of performance benefits. In addition to vitamins and minerals, raw fruits and vegetables also provide water, electrolytes and high quality, low glycemic sugar. This sugar is stored in your liver and muscles for thinking and exercise.
An additional benefit associated with raw fruits and vegetables is that the body stores 2.7 grams of water as it stores 1 gram of carbohydrates (in the form of glycogen) in your liver and muscles. Think about this, eating fresh fruits and vegetables “pre hydrates” the body along with providing high quality sugar for energy, vitamins, minerals and a good source of water (fruits and vegetables contain a high level of water naturally).
The Role of Carbohydrates during Training or Racing
As you breathe and move throughout the day, your body uses a combination of protein, fat and carbohydrates. Protein can provide you up to 15% of your energy needs; the remaining 85% of your energy comes from a combination of stored glycogen levels & body fat – I refer to this as an energy matrix. The higher your intensity levels (easily monitored with a heart rate monitor), the higher the percentage of carbohydrates and less fat you are using for energy.
The average individual stores approximately 60-90 minutes of stored sugar to fuel activity; however, the intensity levels dictate how long this stored sugar will last. Think about this “storage tank” just like the gas tank in your car – your car holds 15 gallons and depending on how fast your drive or the load levels placed on your motor dictate your fuel economy
Carbohydrates Post Exercise
Now that you understand the importance of stored sugar (glycogen) as it relates to performance, your nutritional focus needs to be on replacing depleted storages within the liver and the muscle as quickly and effectively as possible.
When you are finished training or racing, you have decreased or possibly depleted the amount of stored sugar you have remaining in your body. This activates an enzyme called the Glyocgen Synthase Enzyme; which is responsible for glycogen storages within the muscles and the liver.
The replenishment of muscle glycogen (aka glycogen synthesis) occurs in two phases:
Phase 1 (20-40 minutes post exercise/racing): 100-150 calories from simple sugar made from real food are preferred along with electrolytes lost through sweat. (Note: this is why my Energy Fuel is made from raw sugar cane wand has electrolytes added). If you have access to a blender for making real food smoothies, click here for some recipes that I use with my clients.
Note: you need sugar as quickly as possible post exercise to take advantage of the hyper activity level of the glycogen synthase enzyme. Some racers have been told to avoid simple sugars because of the negative effects associated with an insulin burst (lower blood sugar levels); however, when your muscle are in a depleted state, the consumed sugar is shunted into the muscles so quickly that the instability of insulin cannot occur.
Phase 2 (40 minutes to 24 hours): high quality complex carbohydrates are ideal because they absorb slowly and reduce the insulin spike (Note: because the glycogen synthase enzyme activity level is low, because of the time associated with exercise is over an hour ago, simple sugars will now create an insulin spike).
The quicker you replenish (through food consumption), the quicker and more effectively you will be at stocking your muscles and liver with fresh sugar which will properly prepare you for your second workout of the day or your first workout for tomorrow.
How Much Carbohydrate Do I Need Per Day?
According to extensive research completed at Dr. David Costill at Ball State University, muscle glycogen levels plateau at an intake of 650 grams of carbohydrates per day. However, depending on the size, biochemical individuality, training intensity and duration levels of the individual, this number can fluctuate substantially.
As a general starting point, I have my clients start at 1.5 grams per hour of exercise. If my client is 150 pounds and training two hours a day, we strive to consume 450 grams throughout the day.
[150 pounds x 1.5 grams x 2 hours of exercise = 450 grams of carbohydrates]. Please keep in mind that this is the starting point. Based on field testing, race results and body composition (percentage of body fat and lean muscle tissue), we adjust carbohydrate intake accordingly. If you are looking for some clean sources of carbohydrates from real food, click here for my daily suggestions.
Creating a Customized Nutritional Plan
As you have seen over the last three weeks, food plays an instrumental role in your health, wellness and ultimately performance. When you look at the big picture of nutrition and hydration, you can see that there are many variables that have to be evaluated regarding what you are eating and the associated results: strength to weight ratios, duration to fatigue (i.e. endurance), lactate tolerance (i.e. sprint speed), race results and physical performance limiters. With my clients I review these testing variables and compare them against their food & hydration logs to help them create a customized nutritional plan to achieve their personal goals & objectives throughout the race season. If you would like for me to do the same for you, please sign up for my four week Nutrition & Hydration class that is hosted LIVE with me on Wednesday evenings from 8-9:00 pm. For information, please click here.
Next week we will look at the importance of water and proper hydration levels as it relates to both your health and optimum performance.
If you have any questions or need anything clarified, please email me directly.
Until next time, Train Smart-Not Hard!