The Great Carbohydrate Debate – How to Lose Weight VIII

In the ongoing effort to lose weight, the uncontroversial first step is to reduce added sugars.  The next step is to reduce refined carbohydrates.  There are many diets that advocate increasing carbohydrate intake instead.  And some of them do indeed work.

Controversy surrounds the humble carbohydrate. Is it good or bad?  From the mid 1950’s to the 2000’s, they were the good guys, the heroes. Low in fat, they were supposed to be our salvation from the phony epidemic of heart disease. The Atkins onslaught of the late 1990s recast them in the role of dietary villain.  Many advocates avoid all carbohydrates.  What, even vegetables and fruits?  Yes, even vegetables and fruits.  So, are carbohydrates good or bad?

Insulin and insulin resistance drive obesity.  Refined carbohydrates such as white sugar and white flour cause the greatest increase in insulin.  These foods are quite fattening. This does not mean that all carbohydrates are similarly bad. There is a substantial difference between ‘good’ carbohydrates (whole fruits and vegetables) and ‘bad’ (sugar and flour).  Kale and broccoli will not make you fat no matter how much you eat.  But eating even modest amounts of sugar can certainly cause weight gain.  Yet both are carbohydrates – so what is the difference?  How do we distinguish the two?

Dr. David Jenkins of the University of Toronto began to tackle this problem in 1981 with the Glycemic Index (GI).  Foods were ranked according to their tendency to raise glucose.  Since dietary protein and fat did not raise the blood glucose appreciably, they were essentially excluded from the GI. It was used exclusively to measure carbohydrate-containing foods. In these foods, there is a close correlation between the GI and insulin stimulating effect.

The GI uses identical 50-gram portions of carbohydrate.  For example, you might take foods such as carrots, watermelon, apples, bread, pancakes, a candy bar, and oatmeal. You measure each portion to contain 50 grams of carbohydrate and then measure the effect on blood glucose. Foods are compared against the reference standard, glucose, which was assigned a value of 100.

However, a standard serving of food may not contain 50 grams of carbohydrate. For example, watermelon has a very high glycemic index of 72, but contains only 5% carbohydrate by weight. Most of the weight is water.   So you would need to eat 1 kilogram (2.2 pounds!) of watermelon to get 50 g of carbohydrate.  This is far in excess of a single serving. A corn tortilla, on the other hand, has a GI of 52. The tortilla is 48% carbohydrate by weight, so you would only have to eat 104g of the tortilla to get 50g of carbohydrate. This is close to a standard serving. The Glycemic Load (GL) index attempts to correct this distortion by adjusting for serving size.  Watermelon turns out to have a very low GL of 4, but the corn tortilla still has a high GL of 25.

Whether we classify carbohydrates by GI or GL, it becomes obvious that there is a clear distinction between refined carbohydrates and unrefined traditional foods.  Western refined foods have a very high GI and GL. Traditional whole foods have low GL scores, despite containing similar amounts of carbohydrate. This is an essential distinguishing feature. Carbohydrates are not inherently fattening. The toxicity lies in the processing.

Refining significantly increases the glycemic index by purifying and concentrating the carbohydrate. Removal of fat, fibre and protein increases the speed of digestion.  The other macronutrients slow down absorption of the carbohydrates. Furthermore, the refined carbohydrates are much easier to absorb. In the example of wheat, modern machine milling has almost completely replaced the traditional stone milling. This allows wheat to be pulverized into the very fine white powder we know as flour. Cocaine users will know that very fine powders are absorbed into the bloodstream much faster than coarse grains. This allows for higher ‘highs’ – both for cocaine and for glucose. The refined wheat causes glucose to spike up. Insulin levels follow.

Secondly, refining encourages overconsumption.  For example, a glass of orange juice may require 4 or 5 oranges.  It is very easy to drink a glass of juice, but eating 5 oranges is not so easy.  By removing everything other than the carbohydrate, we tend to over consume what is left.  If we had to eat all the fibre and bulk associated with 5 oranges, we may think twice about it. The same applies to grains and vegetables.  If we remove all the bran and fibre and fat from wheat and turn it into white flour, it is very easy to eat.  Dr. Andreas Eenfeldt of www.dietdoctor.com compared identical 30g portions of carbohydrates in vegetables to bread. The bun contains almost pure carbohydrate in an easily digestible form. The pile of vegetables contains significant amounts of fibre and fat. One is highly refined, the other is not. One will cause obesity, the other will not.

The problem is one of balance. Our bodies have adapted to the balance of nutrients in natural food. By refining foods and only consuming a certain portion, the balance is entirely destroyed. People have been eating unrefined carbohydrates for thousands of years without obesity or diabetes.  What has changed recently, is that we now predominantly eat refined grains as our carbohydrate of choice. In Western societies, wheat is often the grain of choice.

Next article:  Fibre – How To Lose Weight IX

Start here with Calories I – How Do We Gain Weight?

2019-01-10T09:49:46-04:000 Comments

About the Author:

Dr. Fung is a Toronto based kidney specialist, having graduated from the University of Toronto and finishing his medical specialty at the University of California, Los Angeles in 2001. He is the author of the bestsellers ‘The Obesity Code’ and ‘The Complete Guide to Fasting’. He has pioneered the use of therapeutic fasting for weight loss and type 2 diabetes reversal in his IDM clinic.

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Apicius
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Apicius

The photo contest above between the veg mix and bread explains why the flour used to make bread is often “fortified”. Fortified flour provides some vitamins and minerals (like iron and vitamin B) which the bread would otherwise be severely deficient in. Even with the use of fortified flour, the bread bun still can’t come anywhere near the level of nutrients the veg mix provides anyway….so why the heck eat the bread?! Clearly, the veg mix is the best choice!!!

John C
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John C

But bread can be so delicious! I manage to control my craving by only eating small amounts very infrequently. Because I eat so little I can afford the luxury of indulging in the highest quality, baking it myself from stone-ground wholemeal flour produced by a restored local watermill from grain grown less than a mile from the mill – so hardly any food miles either! Even our four year old grandchildren know the difference between healthy food and occasional treats. We do our best to encourage their consumption of the former without denying them the pleasure of sensible amounts of… Read more »

jampa
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jampa

Whole wheat flour three roti. How many calories and carbohydrate. How much sugar will go up.

Subra
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Subra

It is difficult to quantify without knowing the size of the Roti. Each Roti can have anywhere from 15g to 40g of Carb depending the on size and thickness. The amount of blood sugar going up is also depends on each person’s ability to consume the glucose. For a prediabetic, it may be 1-2 points of increase in blood sugar for every gram of Carb. For diabetics, it can be as high as 3-5 points of increase for every gram. It is best to measure it yourself 2 hours after meal or 1-1/2 hours after meal. I am prediabetic. Just… Read more »

Faith
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Faith

Also atta, although promoted as “whole wheat” is processed until its very fine not coarse. Thats why it can raise blood sugar almost as much as maida.(in my blood)

Murray
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Murray

I hesitate to classify kale or other leafy greens as carbohydrates. Much if not most of the fibre is transformed by gut bacteria into butyrate and other short chain saturated fats. So it would be more appropriate to classify them as a good source of saturated fat. Misclassifying greens as carbohydrates can lead to problems, as at the Cleveland zoo. Gorillas were fed a vitamin-rich, anti-oxidant rich whole-food fruit and vegetable diet, and got fat and heart disease. Then it was realized that gorillas in the wild eat loads of leafy greens, which spend a lot of time in the… Read more »

kfacwpup
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Approx 2/3 of calories of kale are carbohydrates. In 1 serving, 6.7 g carbs, 1.3g fiber. Still leaves majority as carbs. But carbs in kale may not be same as bread (amylopectin and amylose), so grouping all carbs together may still be wrong.

erdoke
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erdoke

There is significant difference even between amylose and amylopectin. These two are metabolized quite differently, human amylases having much higher affinity to the branched amylopectin. This way a lot of amylose makes it to the large intestines where bacteria ferment it to butyrate, as mentioned by Murray.
Starch refineries often pay more for a mutant corn variety called waxy corn, because it is amylopectin only, hence much easier to process. If a high amylose raw material is usually undesirable for refiners it is usually very desirable for humans. :o)

Alec
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Alec

Veg contains significant amounts of fat?

Webgrrrl
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Webgrrrl

Yes, leafy greens become fat because the gut microbiome eats thrm & delivers fatty acids to your colon cells. We aren’t what we eat; we are what our gut microbiome makes from what we eat & then gives to us. Since we barely understand the complexity of this, we should ditch talking about green veggie carbs at all. Cuz we don’t really understand the synergy we have with our bacteria. The focus should be ditching flour, added sugars, grains & low-fiber white tubers.

Alec
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Alec

But Dr Fung seems to be saying veg contains fat…

“The pile of vegetables contains significant amounts of fibre and fat.”

yy
Guest
yy

The fat is from the nuts, I think.

Michael
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Michael

And olives

Valerie
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Valerie

The table showing the glycemic loads seems fishy. It looks like the portions used for the traditional foods are about half of the portions used for western foods. For instance: The portion of white bread must contain about 25 grams of carbs to give a glycemic load of 34.7 given that its glycemic index is 70. That would be about a slice and a half, or around 120 calories of bread. Following the same type of calculations, the portion of baked potatoes must contain about 11 grams of carbs. That’s a much smaller portion! It would be about one half… Read more »

kfacwpup
Member

This table was from Loren Cordain’s peer reviewed published paper. I did not review each calc myself.

paula isenberg
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paula isenberg

what is your perspective on artificial sweeteners ie splenda

kfacwpup
Member

Avoid. See previous post The Diet Soda Delusion.

Zoltan
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Zoltan

Jason, you wrote: “Removal of fat, fibre and protein increases the speed of digestion. The other macronutrients slow down absorption of the carbohydrates.” This is of greater significance than most people – perhaps most professionals – realise. Adding fat to a high-carbohydrate food item reduces its glycemic index dramatically. As evidenced in the included table, white bread and (at least some kinds of) whole-wheat bread have almost identical GIs… when consumed on their own, which is seldom the case. Spread some butter, goose fat, duck fat – or even lard – on that bread and the GI plummets. This means… Read more »

erdoke
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erdoke

Zoltan, If you read further into the linked paper there is a table with insulin indices. I believe that is the most important learning from the study and also the topic where Jason is heading. Glucose alone pushed fasting insulin to 3.4 while the potato with all “mitigating agents” added on top ends up at 3.2. I still prefer just to consume the mitigating agents… Of course, healthy, insulin sensitive individuals might not have any issues with the potato containing stuff, but whenever turning back a severe insulin resistance is at stake, I just would not take the risk. Thanks… Read more »

Jill
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Jill

I tested my blood glucose one hour after a fat and protein meal. 4.9. A few days later I tested after a high carb meal. 11.2.

Jeff Consiglio
Guest

One thing to also consider is that both the glycemic index and glycemic load concepts utterly fail to take into account the amount of fructose in a given portion of food. Since fructose has to be metabolized by the liver first, it doesn’t cause an “immediate rise” in BG levels, but it sure can contribute to long-term insulin resistance nonetheless. And as much as I hate to vilify fruit, it’s worth considering the fact that modern hybridized fruits have been bred, in recent times, to be unusually big and sugar-loaded. Mankind’s modification of natural fruits arguably puts some fruits into… Read more »

kfacwpup
Member