This article is an excerpt from Dr. Tindall’s book, Nutrition Made Simple.
As with every other aspect of nutrition, one will hear so much about carbohydrates. From some sources, you will hear they are bad for you thus, consume minimal carbs in your diet. From others, you will come to learn that carbs are very healthy and to have lots of them. The fact is, carbs come in all kinds of foods from breads to pastas to veggies to simple sugars. As you’ll read below from this book excerpt, carbohydrates are a necessary part of the diet. We have added some additional tips in italics within the text.
What Portion of Carbohydrates Should I Use in My Diet? (45 to 55 percent)
Your diet should be high in complex carbohydrates rather than fat. Complex does not mean donuts, candy, soda, or similar foods. Starches such as grains, brown pastas, fruit, and vegetables should be emphasized. The average person should consume about 45-55 percent carbohydrates in his or her overall nutritional plan as a percent of the total daily caloric intake. Some individuals can consume up to 65 percent due to physical activity. [Of course, if you are planning for a competition in bodybuilding, your will wean carbohydrates down significantly as you approach competition day.]
While carbohydrates provide energy (4 calories per gram), the important point is what kind of carbohydrate to use in your menu plan. There are essentially three different types of carbohydrates:
(1) monosaccharide’s (glucose and fructose from fruits);
(2) disaccharides (table sugar); and
(3) polysaccharides (legumes, grains, nuts, and vegetables).
If you eat too much mono- or disaccharides at one time, the body’s insulin levels are spiked (increased) far greater than normal, resulting in a “crash” or drowsiness. I will discuss this in greater detail later in the “Glycemic Index” section. By eating complex carbohydrates throughout the day (polysaccharides), insulin levels are maintained and controlled, resulting in more sustained energy and increased ability to lose weight. Also, too much of any kind of carbohydrate results in fat storage, so it is necessary to eat complex carbohydrates in small amounts throughout the day for a specific total based on body weight (see table 2.5). It should be noted here that no RDA has yet been determined for carbohydrates, but based upon scientific research, I will offer some guidelines as to the amounts that should be eaten based on your activity level. Remember that 1 gram of carbs is equal to 4 calories.
Table 2.5. Carbohydrate Index – Requirements per day (grams).
|Body Weight (lbs)||Training (hours per day)|
|Carbohydrate Requirements (grams per day)|
Through digestion, carbohydrates are broken down into fructose, glucose, and galactose. These forms enter the intestinal cells, are transported by the portal vein to the liver, which then transforms them into glucose and releases them into the bloodstream. The primary function of glucose is to supply the body with energy. Certain tissues, such as red blood cells, can use only glucose and other simple carbohydrate forms for energy. Most parts of the brain also obtain energy only from simple carbohydrates unless the body contains almost none. This is a primary defect of limiting macronutrients, specifically carbohydrates such as in the Atkins diet. When the brain cannot obtain energy from glucose, it uses partial breakdown products of fat, called ketones, for energy.
Consequently, when you do not eat enough carbohydrates, fats don’t break down completely during metabolism, i.e., fat metabolism is hampered without the presence of adequate carbohydrates, hence the saying “fat burns in a carbohydrate flame” among nutritionists. When this happens, it is called ketosis and it disturbs the body’s normal acid-base balance, which leads to other health problems. A minimum of 50 to 100 grams of carbohydrates per day will ensure complete metabolism of fats, or that ketosis will be prevented. Too many carbohydrates will prevent metabolism (burning) of stored fats.
Tip: About 8 grams of carbohydrates are required to adequately burn 1 gram of fat.
As an example of the carbohydrate requirements listed in table 2.5, suppose an individual that weighs 176 pounds works out for one hour at golf, 1.5 hours lifting and 2.5 hours of golf technique work; a total of 5 hours. What are the carbohydrate requirements for this person? Simply read down the table to find the weight and across to find the number of hours’ exercise; the carbohydrate requirement is 900 grams. If an individual’s weight is between those listed, simply add, or subtract 50 grams of carbohydrates to or from the listed requirements. For example, suppose a person weighed 125 pounds or 155 pounds, the carbohydrate requirement would be 650 and 850 grams respectively. If intensity during exercise is lower, decrease this amount further.
Carbohydrate Fuel Use
Have you ever wondered why you get muscle burn? It’s caused by lactic acid build up. Why? When carbohydrates, i.e., the glucose manufactured in the body by their ingestion, break down into three carbon compounds, they follow one of two main routes depending on the amount of oxygen present in the muscle. When oxygen supply is limited in anaerobic conditions the three-carbon compounds accumulate in the muscle and is converted to lactic acid; no further ATP is directly formed. Activities that make this occur are sprinting and other short duration, high intensity exercises like weight lifting. The conversion of glucose to lactic acid is termed anaerobic glycolysis.
Carbohydrate is the only fuel that can be used for this—during the exercise, not afterward. If plenty of oxygen is available to the muscle, we have aerobic conditions; the exercises in this category would be of low to moderate intensity such as jogging or long-distance running or swimming.
Because you may work out quite often, compete in half marathons and perform other types of competitive events or may wish to, such as a friend of mine who ran her first marathon last year, the timing of carbohydrates, regarding when to eat them, can be important. There are three periods when the timing of carbohydrate intake is essential for the best results in physical activities—pre-workout, workout, and post-workout carbohydrates. First, in the pre-workout meal, you should consume about 100 grams of complex carbohydrates. This should occur about 3 hours prior to the workout. Second, during the workout, drink a 5-10 percent carbohydrate beverage between sets. Third, consume a carbohydrate drink of some kind with glucose and fructose (about 22.5 grams) immediately following the workout. By following these three simple steps, you can keep your energy level up for exercise demands and cut recovery time in half because your muscles are kept filled with glycogen, which is converted into ATP. For the competitors among you, Appendix 1 discusses carbohydrate (‘carb’) loading.
Simple carbohydrates are used mainly during exercise and directly following exercise. The insulin spike is not obtained because of the depleted muscles and the need by the muscles for carbohydrates. The use of complex carbohydrates directly after a workout will reduce recovery time compared to the use of simple carbohydrates (see table 2.5 for requirements).
2.12 Glycemic Index
The glycemic index is important in a diet. This index refers to the rate at which carbohydrates are broken down into glucose and released into the bloodstream. Think of your cells as tiny gas tanks; the gas in your cells is glucose. As an example, a simple sugar is broken down fast and causes a burst of energy for a short period. Also, carbohydrates that are not used are stored as fat somewhere on the body. In comparison, complex carbohydrates with a low glycemic index break down and release energy very slowly, causing a sustained energy level for longer periods without fat storage occurring. Therefore you should eliminate excess sugars from your diet. A soft drink is okay occasionally, but not several cans of soda or beer per day! Some of the foods that should be avoided and some that should be eaten are listed in table 2.7. [This table is available in the book, but not listed here due to a variety of factors.]
Why is the Glycemic Index Important?
The primary source of weight gain, other than lack of exercise, is sugar intake at the wrong time, and in too large a quantity. Yes, that cola, ice cream, or large plate of pasta you may be eating right now. Not all sugar is bad, but it should be eaten in moderation. Let’s explain it in lay terms. Because of the effects of sugar and other forms of carbohydrates on blood-sugar levels, we shall refer to insulin for illustration of this concept, which is a hormone produced by the beta cells of the pancreas, as the insulin level. This is because of the general appearance of the blood sugar level as it rises and falls in response to sugar intake and insulin release has a cyclic appearance.
Insulin increases the synthesis of glycogen in the liver and the movement of glucose from the bloodstream into body cells.
How is blood sugar level controlled? The pancreas works with the liver to perform this task. When you begin eating, the pancreas releases small amounts of insulin. When a lot of glucose (sugar in lay terms) enters the bloodstream, the pancreas releases more insulin. This insulin stimulates the liver to synthesize glycogen, the storage form of glucose, i.e., your ‘cell sugar’ in the body, and stimulates adipose (fat) cells, muscle cells, and other cells to increase glucose uptake. By triggering both glucose storage in the liver and glucose movement from the bloodstream into various types of cells, insulin keeps glucose from rising too high in the blood. If you have diabetes you understand how critical and important this is.
Bear with me as I attempt to explain the insulin level and glucagon secretion in lay terms. The insulin level is a representative norm for a diabetic or healthy individual who doesn’t eat too much sugar or large portions of carbohydrates at one time. Insulin levels typically fluctuate a little; this is often referred to as your blood-sugar level. By keeping these levels steady, it is almost impossible to gain weight or put fat on the body! And, you can do this if you don’t over eat carbohydrates and indulge in too many sweets.
Tip: Limit yourself to no more than 35 grams of carbohydrates per serving then, you can keep from spiking your insulin level.
Glucagon secretion, what is commonly referred to as the Glucagon Cycle and is the cycle in your body that is responsible for burning or metabolizing fat already stored on your body. Glucagon is a hormone made by the pancreas that stimulates the breakdown of glycogen in the liver into glucose, which increases blood glucose. When the correct types of food are eaten in combination, it works with insulin levels and both are in normal parameters to help you maintain a strong, healthy body that has less fat on it.
What happens when you eat a large portion of complex carbohydrates such as bread or pasta, or simple carbohydrates such as a coke, candy bar, or ice cream? The result is a spiked insulin level. For example, drinking a regular coke creates a spiked insulin level for about 2-4 hours or more, depending on the amount of carbohydrate or sugar intake. The effect can become more pronounced for persons 35 years old and older. Also, increased amounts of sugar usage will increase cholesterol in the blood. When the insulin level begins to fall, you will notice the ‘crash’ that is typically exhibited as drowsiness or sluggishness. You know, you’ve experienced it, that early morning crash you got from eating that cinnamon roll, donut, or sugar frosted corn flakes!
Eating large amounts of sugar or carbohydrates causes a double whammy. It will spike the insulin level and also cause an immediate depression of your fat burning metabolism, which makes it impossible, during the period of the spiked cycle, for your body to burn or metabolize stored fat. Thus, you’ll end up gaining unwanted pounds. Also, the intake of alcohol, since it is high in sugar, is even more exacerbated because the alcohol serves as the body’s immediate energy source leaving the sugar to be stored as fat as well.
Again, I am not implying that you cannot eat sugar. It’s okay to celebrate the birthday or have a nice dessert once or twice a week. But, if you’re drinking 3 to 5 cans of soda per day, reduce it to one can or so every 2 to 3 days [or further apart]. Besides, these kinds of foods have minimal nutritional value and do little for your overall health when eaten in larger portions, which is in addition to the effects discussed here. Use sugar as a reward for hard work. It is very appropriate to drink something such as grape juice (4 to 8 ounces), about 20 to 30 minutes prior to your workout. For those who wish a more detailed, technical description of this process, it is included, along with graphs for a visual effect in Appendix 2.
Tip: Eat complex carbohydrates in smaller meals throughout the day. This will lessen the chance of a spiked insulin level and allow more of your food and stored fat to be burned as energy, giving you the healthy body you desire and keep your insulin level down.
Now, you have a better understanding about why carbohydrates are an essential part of your diet. Go workout, have fun, and enjoy your new knowledge.