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Fueling Workouts

This is an excerpt from Power Eating-4th Edition by Susan Kleiner & Maggie Greenwood-Robinson.

Fueling Workouts

From the oatmeal you eat for breakfast to the baked potato you eat for dinner, carbohydrate is the leading nutrient fuel for your body. During digestion, carbohydrate is broken down into glucose. Glucose circulates in the blood, where it is known as blood sugar, to be used by the brain and nervous system for energy. If your brain cells are deprived of glucose, your mental power will suffer, and because your brain controls your muscles, you might even feel weak and shaky.


Glucose from the breakdown of carbohydrate is also converted to glycogen for storage in either liver or muscle. Two thirds of your body’s glycogen is stored in the muscles, and about one third is stored in the liver. When muscles use glycogen, they break it back down into glucose through a series of energy-producing steps.


It is no surprise that vegetables, fruit, cereal, pasta, grains, sport drinks, energy bars, and other forms of carbohydrate are the foods of choice for endurance athletes, who load up on carbohydrate to improve their performance in competition. But carbohydrate is just as necessary for strength trainers as it is for endurance athletes—in the right amounts, and combined with protein and fat. The glycogen provided by carbohydrate is the major source of fuel for working muscles. When carbohydrate is in short supply, your muscles get tired and heavy. Carbohydrate, particularly in combination with protein and fat, is thus a vital nutrient that keeps your mind and muscles powered up for hard training and muscle building.


The amount of carbohydrate you need in your diet each day varies, depending on your training goals, how frequently and intensively you train, your gender, and your own individual needs. After decades of working with athletes at all levels and in all kinds of sports, I have noted that carbohydrate is needed in highly variable amounts from one individual to another even doing the same level of exercise. In general, to fuel performance, athletes need from 4.5 to 10 grams of carbohydrate per kilogram of body weight every day. This very large range depends on the factors noted earlier, including the type of exercise; exercise goals; the frequency, intensity, and duration of exercise; gender; and the weight requirements of the sport. Carbohydrate needs are different still when the goal of the diet and training program is to lose fat. That discussion can be found in chapters 4 and 5 of this book.


The Force Behind Muscle Building and Fat Burning

Among the nutrients, carbohydrate is the most powerful in affecting your energy levels. But it also affects your muscle-building and fat-burning power. It takes about 2,500 calories to build just 1 pound (0.5 kg) of muscle. That’s a lot of energy! The best source of that energy is carbohydrate. It provides the cleanest, most immediate source of energy for body cells. In fact, your body prefers to burn carbohydrate over fat or protein. As your body’s favored fuel source, carbohydrate spares protein from being used as energy. Protein is thus free to do its main job—building and repairing body tissue, including muscle.


Carbohydrate is a must for efficient fat burning, too. Your body burns fat for energy in a series of complex chemical reactions that take place inside cells. Think of fat as a log on a hearth waiting to be ignited. Carbohydrate is the match that ignites fat at the cellular level. Unless enough carbohydrate is available in key stages of the energy-producing process, fat will just smolder—in other words, not burn as cleanly or completely.


Carbohydrate also raises carnitine levels in muscle cells. Carnitine is an amino acid-like nutrient that carries fat into the mitochondria of cells (the machinery that burns fat for fuel). Researchers at the University of Nottingham gave healthy young men carnitine, as well as insulin and glucose, intravenously at the same time. The researchers supplied just enough glucose to keep the blood sugar levels of their subjects constant. The treatment lasted for five hours.


The more insulin is circulating in the body, the higher the level of carnitine in the muscles following carnitine supplementation. This suggests that carnitine probably works best when taken with a well-balanced meal that includes carbohydrate.


The implication here is that endurance athletes who load up on carbohydrate before a race might be further helped by carnitine supplements. The same may be true for high-power athletes such as downhill mountain bike racers, who operate in the anaerobic zone almost exclusively. These athletes may even be helped more by carnitine supplementation. Strength trainers who want to give their muscles a glycogen boost before training may also find a benefit. Keep in mind that the research in this area is very young, and we don’t know whether the results from dietary consumption are specific to the type of carnitine and carbohydrate used in the study, or that it’s a generalized effect. Clearly, the insulin spike is a key component to getting carnitine into muscle cells.


Increase Carbohydrate Calories

The most important nutritional factor affecting muscle gain is calories—specifically, calories from carbohydrate. Building muscle requires a rigorous strength-training program. A tremendous amount of energy is required to fuel this type of exercise—energy that is best supplied by carbohydrate. A carbohydrate-dense diet allows for the greatest recovery of muscle glycogen stores on a daily basis. This ongoing replenishment lets your muscles work equally hard on successive days. Studies continue to show that carbohydrate-dense diets give strength-training athletes an edge in their workouts; and the bottom line is, the harder you train, the more muscle you can build.


To build 1 pound (0.5 kg) of muscle, add 2,500 calories a week. This means introducing extra calories into your diet. Ideally, women must increase their calorie intake by 300 a day; and men, by 400. Research has shown this to be the optimal increase to begin building muscle and minimize fat gain.


You should increase your calorie consumption gradually so that you don’t gain too much fat. What I suggest to strength trainers in a building phase is to start by introducing only 300 to 350 more calories per day. Then after a week or two, add another 300 to 400 calories a day. As long as you’re not gaining fat, start introducing extra calories into your diet weekly, again at the same rate of 300 to 400 calories. (Incidentally, for losing fat, you can drop calories by the same amount—300 calories a day for women and 400 calories a day for men.)


But back to increasing calories: Most of these additional calories should come from carbohydrate in the form of food and liquid carbohydrate supplements. An example of 300 to 400 calories worth of carbohydrate from food is 1/2 cup (70 g) of whole-grain pasta, 1/2 cup of yams (68 g) and one banana. It just doesn’t take that much additional food to increase your carbohydrate intake. Later in the book, I’ll show you how to time your carbohydrate intake properly and how to combine the additional carbohydrate with the right foods to enhance muscle building.


When I’m working with athletes, I make sure their protein and fat needs are taken care of; then I look at their carbohydrate intake. I adjust calories by increasing or decreasing carbohydrate calories. Carbohydrate calories are the fuel, so if someone wants to gain weight, carbohydrate calories go up; to lose fat, carbohydrate calories go down. Remember, you should always eat carbohydrate in combination with the right amounts of protein and fat; it should not be consumed alone except perhaps in a sport drink when you just can’t eat any additional solid food. (Sport drinks, however, should only be consumed during training, not as a beverage during the day.)


To be really exact, you can match your carbohydrate intake to your weight. If you are a strength trainer and want to build muscle, you should take in about 4.5 to 7 grams of carbohydrate per kilogram of body weight a day, depending on whether you are female or male and the stage of your training. An athlete who cross-trains with strength training, wants to build, and does any type of endurance activity needs anywhere from 5 to more than 10 grams per kilogram of body weight a day based on the same factors.

Learn more about Power Eating, Fourth Edition.

More Excerpts From Power Eating 4th Edition