Carbohydrate is actually so vital to your health that your body will begin to make carbohydrate (glucose) out of muscle or organ protein if you don't eat enough.
But this often means you are losing muscle or organ tissue, which dieters do not want to do, because these are the main "fat-burning" tissues of the body. So the less of them you have the harder it is to lose weight.
Most people know that the brain and nervous system strongly "prefer" to use glucose for fuel whenever it is sufficiently available. But these organs can, in an emergency, use the "ketone bodies" from fat metabolism as fuel instead.
But this is not true for certain blood and other cells in your body. They must have glucose or die.
For this reason, when it doesn't get enough dietary carbohydrate, your body will make a minimum amount of glucose out of your muscle or organ tissue to keep these blood cells alive.
You lose muscle when muscle tissue is used to make glucose.
You do not want this to happen!
Muscles and organs "prefer" to use fat for fuel. The more muscle you have, the more fat is used -- 24/7. Losing weight becomes more difficult as you lose more muscle.
For this reason, dieters want to eat enough carbohydrate to prevent muscle loss. The current "best estimate" of the minimum needed to do this is between 50 and 100 grams per day (which is 200-400 Calories).
However, too much carbohydrate also prevents weight loss, because when your body is busy burning the Calories in the excess carbohydrate you just ate, it's not burning the excess Calories in your fat cells. And that's no way to lose weight.
There are several other carbohydrate- related issues you may want to know about. We discuss them in the next several parts of this section.
Only fat makes you fat…
but carbohydrate can prevent you
from ever losing that fat.
As with other nutrients on the diet, managing carbohydrate means consciously controlling both the type and the amount that you eat. The body uses carbohydrate almost solely as a source of energy (Calories). Therefore, on the diet we want to restrict carbohydrate so that the body will have to use mainly stored fat for energy instead.
However, “restrict” does not mean “eliminate”—which is not really possible and would be undesirable anyway. The diet is not an ultra-low-carbohydrate diet. Once you have gotten your required amount of protein and fatty acids (and the Calories that inevitably go with them), all other Calories up to your daily Calorie limit can and should come from carbohydrate. But it should be the right type of carbohydrate. This means “low-glycemic-index” carbohydrate.
When dieters work with carbohydrate, we are primarily trying to manage two things: energy (Calories) and insulin (metabolism). Research has recently given us simple ways to do each. We discuss them in the next two sections.
For dieters, carbohydrate is the least “essential” of the vital nutrients. But it is not totally superfluous. Although you can survive indefinitely without carbohydrates if your diet contains sufficient protein and fat, hunger will be awakened and very unhappy about it. This is due to the requirements for carbohydrate in the metabolic functions discussed earlier in Part Two in more on… energy metabolism & storage. Therefore, on the diet we do not eliminate carbohydrate. We do, however, restrict it—both as to amount and as to type. Carbohydrate quality is usually less critical than carbohydrate quantity as long as you observe the basic diet principle: Neither too much nor too little nor the wrong type.
To keep carbohydrate intake restricted to a reasonable amount of energy, we use our own diet variant of the “carbohydrate-by-difference” approach to energy measurement.
First make sure you get enough protein.
Then make sure you get enough EFAs.
Then make up your daily Calorie limit with carbohydrate.
Below is another calculation table to help you “work your own numbers” on carbohydrate.
Note that eating less than the amount of carbohydrate you calculate in Table 20 is probably ok—as long as you get at least 200–400 Calories (50–100 grams) of it per day.
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Table 20: Your Carbohydrate Calories Your Carbohydrate Calories |
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Your Daily Calorie Limit |
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Minus Calories from Protein |
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Minus Calories from Essential Oil |
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Equals Calories from Carbohydrate (max) |
____ kcal |
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(Note: You can divide carbohydrate calories by 4 to get carbohydrate grams—but for diet purposes you don’t need to know this.) |
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You need a minimum amount of daily dietary carbohydrate because certain tissues in your body (e.g. certain blood cells) must have glucose for energy—they cannot use anything else and will die if they don’t have it. In fact, if there is insufficient glucose available from dietary carbohydrate, your body will make the glucose they must have out of muscle protein—and we don’t want that. The amount of dietary carbohydrate required to prevent this is believed to be fifty to one hundred grams per day (200-400 Calories). This amount of dietary carbohydrate is therefore usually said to have a “protein-sparing” effect. (See more on… energy metabolism & storage.)
As we discussed in more on… energy metabolism & storage, your digestive system converts carbohydrate to glucose—which enters the bloodstream almost immediately. However, when a large amount of glucose suddenly shows up in the blood, your body must release a large amount of insulin to deal with it. From the dieter’s point of view large amounts of insulin cause several negative things to happen, i.e. none of them are much good for losing fat.
A sudden large amount of insulin entering the blood may overcompensate for the amount of glucose it is supposed to deal with. This causes an unpleasant state called “reactive hypoglycemia” . If it happens, blood glucose levels are forced below normal for a period of time. During this time various organs (mainly the brain and nervous system) will get less glucose than they want. They then tend to “wake hunger” to stimulate you to go eat to get them some more glucose. (This is not good, since hunger will probably want you to eat a few slices of some “low-calorie” food like pizza or chocolate cheesecake.)
Insulin tells fat cells to stop releasing fat into the bloodstream to be burned for fuel by other cells (not good).
It also tells the fat cells to pick up and store any fat that may enter the blood along with the carbohydrate you eat, rather than releasing it for other cells to use for fuel (not good).
It tells muscles and other tissues that are already burning fat to switch over to burning glucose instead (not good).
It tells the liver and muscle cells to start converting glucose to glycogen for storage (not so bad).
But when glycogen stores are full (and possibly before), it tells the liver and fat cells to start converting the glucose into FAT (very bad).
Since all of these insulin effects make it harder to lose fat, we would obviously like to prevent those “large amounts of glucose” from stimulating release of those “large amounts of insulin”. How can this be done?
Obviously, eating almost no carbohydrate would be one way to avoid these problems—but under normal circumstances it’s not very practical. Fortunately, it’s also not necessary. Eating the right type of carbohydrate in more or less normal amounts has a much more balanced effect on your blood chemistry and a much less disruptive effect on your life. Specifically, the right types of carbohydrate are digested and absorbed very slo-o-o-w-ly into the bloodstream. They therefore do not cause that large rise in blood sugar followed by that correspondingly large insulin response. This “speed of absorption” is measured by…
The glycemic index (G.I.) is a numerical measurement of how fast the digestive system converts the carbohydrate in a particular food into glucose and gets it into the bloodstream. Higher G.I.s mean faster absorption and may cause reactive hypoglycemia. Lower G.I.s mean slower absorption and probably won’t.
The glycemic index measures the magnitude and duration of the increase in blood glucose level (bG) after a given type of food is eaten. To determine this, volunteers eat a specific food in an amount that is known to contain 50 grams of available carbohydrate. Their blood glucose levels are measured for the next three hours. From these measurements, the effect of that particular food on blood glucose is calculated and expressed as a single number—the glycemic index.
The glycemic index compares the effect on blood glucose of eating that particular food to the effect of eating the same amount of pure glucose (the reference standard). For example, the G.I. of navy beans is about 40. This means that it raises blood glucose (bG) only about 40% as much as the same amount of pure glucose would (this is a relatively low glycemic index). (Note: White bread is also often used as a reference standard because it’s easier to test. It gives different absolute G.I. numbers but the same relative rankings among foods—which is what’s important.)
There are some foods whose glycemic index will probably never be measured. For example, in order to get 50g of carbohydrate from Celery some poor volunteer would have to eat about 35 eight-inch stalks of it. And when you consider the testing protocol says that the same person has to do this three times…Yuck! (Maybe if you pay me 500, no, make that 1000 bucks each time…)
The glycemic index technique is used in diabetes medicine where it was developed as a tool to help diabetics control blood sugar. However, even in diabetes medicine, the glycemic index is a relatively new measurement only just now gaining mainstream acceptance. Canadian professor of nutrition David Jenkins first proposed it in 1981 (“only” about 20 years agoJ). Since then the concept has proven to give predictable and reproducible results. Previously, scientists had simply assumed that “complex carbohydrates” were absorbed slowly and caused only moderate blood glucose rises (this is often wrong) and that “simple sugars” were absorbed rapidly and caused sudden rises (also often wrong). The glycemic index technique replaces these assumptions with actual measurements—almost always a more accurate way to discover the truth.J
About 600 different foods (or varieties of foods) have been tested to determine their glycemic indices. The results of these tests have been summarized into tables. Most such tables are based on a reference standard of either glucose or white bread. The diet Glycemic Index Chart uses glucose as the standard.
Glycemic index tables must be used with some caution. Many things can cause the G.I. value of a particular food you are eating to be different from the G.I. value of the same food when it was tested. The difference is usually minor, but in a few cases it can be significant. Rice is an example. Rice contains two types of carbohydrate (as starch)—amylose (which has a low G.I.) and amylopectin (which has a high G.I.). Rice varieties that have more amylose have lower G.I.s, and varieties that have more amylopectin have higher G.I.s. Rice, depending on the variety, can be high or low in either type and consequently the rice you may be eating may have a high or low G.I. regardless of what a particular G.I. table says.
The rate of glucose absorption of a particular serving of food can be influenced by lots of other things also, including: the method of food-processing used, the method of cooking, ripeness, amounts of protein and fat in the meal, type and length of storage, and your individual biochemistry. But these other things being equal, you will always have a greater glucose/insulin response to a high-GI food than to a low-GI food by approximately the amount suggested by the glycemic index of the food.
Note: Diabetics and others who wish to understand the current state of the art in glycemic index research by one of its leading proponents should read The G. I. Factor: The Glycaemic Index Solution by Prof. Janette C. Brand Miller.
The diet Glycemic Index Chart shows the foods with known G.I.s that are most useful to dieters.
It also shows the range of variability in the G.I. of each food. For example, carrots have a G.I. of 71±22. This means the carrots you get at the store might have a G.I. of 49 (fairly low), or a G.I. of 93 (almost the same as glucose itself!), or a G.I. anywhere in between.
A “high” G.I. is usually considered to be any G.I. over one-half (½) the value of glucose. This is about 50 on the glucose standard (about 70 on the white bread standard).
We dieters can still eat high-G.I. foods of course, but the rule-of-thumb for them is: The higher the G.I., the less of it you should eat at any one time!
It’s for this reason that I tend to recommend popcorn as a good food for “munchie” type situations. Popcorn does have a high G.I. But since it’s mostly air and has very little actual carbohydrate for a given volume, it seems like a lot and can keep you occupied for a while longer than other foods.(Try a very short “spritz” of one of those cooking sprays on it to hold the salt—the extra Calories are completely insignificant.
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