The Diabetes Diet
Richard K. Bernstein, MD, FACE, FACN, FACCWS
Part 1 of Chapter 3
Essential Guidelines for the Diabetes Diet
WHY YOU OUGHT TO IGNORE THE GLYCEMIC INDEX
In the days before low-carb diets began their tremendous upswing in popularity, it was difficult for people to over-come resistance to the idea of restricting carbohydrate in their diet. That job has become easier in the last few years, but at the same time there is still a tremendous amount of confusion about what carbohydrate foods ought to be emphasized and what ought to be restricted.
You’ll hear people talk incessantly about complex and simple carbohydrates, but those are very loose categories and change depending on who is doing the talking. For our purposes, “good” carbohydrate is slow-acting and not concentrated.
In keeping with the Laws of Small Numbers, good carbohydrate has a small impact on your blood sugar. Examples are whole-plant vegetables, leafy greens, mushrooms, and many others. These are foods that are either very difficult or impossible for the body to break down into glucose.
Cellulose is a major component of vegetable foods in addition, it’s also a major component of wood — and while it is technically a carbohydrate, humans lack the enzymes to break it down. Cellulose is beneficial in a number of different ways, but most significant for our purposes is that cellulose “dilutes” the digestible carbohydrate and thereby slows its absorption. (Interestingly, eating fat with carbohydrate can further slow the digestion of carbohydrate, so if you have butter on your string beans or oil and vinegar on your green salad, this addition of fat will slow the absorption of the digestible carbohydrate.)
“Bad” carbohydrate is fast-acting or concentrated carbohydrate. This includes everything from straight table sugar to so-called complex carbohydrates like potatoes, carrots, whole grain bread, and peas (and many others).
SOME WORDS ABOUT CALORIES, AND WHY YOU OUGHT TO IGNORE THE GLYCEMIC INDEX
One of the most popular concepts with respect to low-carb diets is the glycemic index. The idea that underlies the glycemic index is that foods can be evaluated for their effect on blood sugars, in much the same way that they can be evaluated for their caloric content. The glycemic index (or GI) is the cornerstone of some of the bestselling lowcarb diets. Even if you have no idea what it is, it’s still likely that you’ve heard of it.
In Australia there is even a nonprofit organization that offers its imprimatur (a bit like the Underwriters Laboratory seal or the Good Housekeeping seal) to foods that “meet specific nutritional criteria and have had their GI measured using the approved method. High, medium, and low GI foods are eligible.” It sounds like an elegant idea. Pure glucose equals 100. Mashed potatoes rate a 90 (depending on the group doing the testing). Table sugar rates a 70. As with a lot of seemingly elegant ideas, however, the reality is far more complex, just as the measure of calories is more complex than it appears.
What a Calorie Really Is
You probably can’t even remember the first time you heard of a calorie. But you know what it is, right? Or do you?
Well, let’s look at calories for a moment. A calorie is an objective measure of energy — specifically, it’s the energy given off as oxygen rapidly oxidizes foodstuffs (that is, when they are burned). One calorie is the amount of energy it takes to raise the temperature of 1 milliliter of water 1 degree Celsius. Our bodies burn energy, but in a much slower and different way than does fire. So when you read a food label and it says 100 calories, this is not a direct measure of anything the food actually does in your body, or of how much it will affect your waistline, but a measure of how much the burning food in a testing laboratory raised the temperature of a specific amount of water. There is a margin for error allowed in food labeling, of course, so the stated measure is not absolutely exact.
By this measure, 1 gram of dietary fat contains 9 calories, 1 gram of dietary protein contains 4 calories, and 1 gram of dietary carbohydrate also contains 4 calories. A gram of alcohol contains 7 calories.
This all sounds very simple and straightforward, but in fact it is not. Consider that if you, like the calorimeter used to measure the calories in food, burned all of the calories in the food you ate, you would rarely need to move your bowels. Consider also that a two-by-four would burn and heat up the water in a calorimeter very nicely, but the calories it contains would be almost entirely from cellulose, the same indigestible fiber making up much of the carbohydrate content of, for example, most vegetables.
Fat, while it will keep your lamp burning, is less straightforward than carbohydrate. Fat plays various and significant roles all over the body — in the brain and in the makeup of hormones and cell membranes throughout — and the body expends more energy extracting the energy from dietary fat than it does extracting the energy from carbohydrate.
Recent evidence has shown that while fat may gross 9 calories per gram, the net available for metabolism is closer to something like 5 calories a gram.
Protein is similarly complicated. Meats, for instance, contain not just protein but also indigestible gristle, water, and fat; beans or other vegetable sources of protein may “trap” some of the protein in indigestible fiber; and of course protein can be used by the body in the form of amino acids or may be slowly converted to glucose. In fact, generally speaking, there are only about 6 grams of real protein in an ounce of a protein food, even though by weight there are 28.47 grams in a U.S. ounce. The Diabetes Diet uses this 6 grams per ounce figure in converting grams of protein (as you might find them listed in food value tables or on nutrition labels) to ounces of a protein food. Chapter 5, Customizing the Diet,” shows you how this works. So the bottom line is that despite our ability to measure the caloric content of foods objectively, what we’re getting is a rough estimate at best.
We would like to thank the publisher Little Brown and Company and Dr. Richard K. Bernstein, for allowing us to provide excerpts from The Diabetes Diet.
Copyright © 2005 by Richard K. Bernstein, M.D. All rights reserved. No part of this book may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review.
This book is not intended as a substitute for professional medical care. The reader should regularly consult a physician for all health-related problems and routine care.
For more information on Dr. Bernstein’s and to purchase his books, CD’s or get access to his free monthly webinars, visit his website at DiabetesBook.com.