Rerun: To let low-carb right, you must check POSTPRANDIAL blood sugars

2. April 2010 William Davis (12)
Checking postprandial (after-eating) blood sugars yields extraordinary advantage in creating better diets for many people.

This idea has proven so powerful that I am running a previous Heart Scan Blog post on this practice to bring any newcomers up-to-date on this powerful way to improve diet, lose weight, reduce small LDL, reduce triglycerides, and reduce blood pressure.



To get low-carb right, you need to check blood sugars

Reducing your carbohydrate exposure, particularly to wheat, cornstarch, and sucrose (table sugar), helps with weight loss; reduction of triglycerides, small LDL, and c-reactive protein; increases HDL; reduces blood pressure. There should be no remaining doubt on these effects.

However, I am going to propose that you cannot truly get your low-carb diet right without checking blood sugars. Let me explain.

Carbohydrates are the dominant driver of blood sugar (glucose) after eating. But it's clear that we also obtain some wonderfully healthy nutrients from carbohydrate sources: Think anthocyanins from blueberries and pomegranates, vitamin C from citrus, and soluble fiber from beans. There are many good things in carbohydrate foods.

How do we weigh the need to reduce carbohydrates with their benefits?

Blood sugar after eating ("postprandial") is the best index of carbohydrate metabolism we have (not fasting blood sugar). It also provides an indirect gauge of small LDL. Checking your blood sugar (glucose) has become an easy and relatively inexpensive tool that just about anybody can incorporate into health habits. More often than not, it can also provide you with some unexpected insights about your response to diet.

If you’re not a diabetic, why bother checking blood sugar? New studies have documented the increased likelihood of cardiovascular events with increased postprandial blood sugars well below the ranges regarded as diabetic. A blood sugar level of 140 mg/dl after a meal carries 30-60% increased (relative) risk for heart attack and other events. The increase in risk begins at even lower levels, perhaps 110 mg/dl or lower after-eating.

We use a one-hour after eating blood sugar to gauge the effects of a meal. If, for instance, your dinner of baked chicken, asparagus brushed with olive oil, sauteed mushrooms, mashed potatoes, and a piece of Italian bread yields a one-hour blood sugar of 155 mg/dl, you know that something is wrong. (This is far more common than most people think.)

Doing this myself, I have been shocked at the times I've had an unexpectedly high blood sugar from seemingly "safe' foods, or when a store- or restaurant-bought meal had some concealed source of sugar or carbohydrate. (I recently had a restaurant meal of a turkey burger with cheese, mixed salad with balsamic vinegar dressing, along with a few bites of my wife's veggie omelet. Blood sugar one hour later: 127 mg/dl. I believe sugar added to the salad dressing was the culprit.)

You can now purchase your own blood glucose monitor at stores like Walmart and Walgreens for $10-20. You will also need to purchase the fingerstick lancets and test strips; the test strips are the most costly part of the picture, usually running $0.50 to $1.00 per test strip. But since people without diabetes check their blood sugar only occasionally, the cost of the test strips is, over time, modest. I've had several devices over the years, but my current favorite for ease-of-use is the LifeScan OneTouch UltraMini that cost me $18.99 at Walgreens.

Checking after-meal blood sugars is, in my view, a powerful means of managing diet when reducing carbohydrate exposure is your goal. It provides immediate feedback on the carbohydrate aspect of your diet, allowing you to adjust and tweak carbohydrate intake to your individual metabolism.

LDL glycation

1. April 2010 William Davis (11)
The proteins of the body are subject to the process of glycation, modification of protein structures by glucose (blood sugar). In the last Heart Scan Blog post, I discussed how glycated hemoglobin, available as a common test called HbA1c, can serve as a reflection of protein glycation (though it does not indicate actual Advanced Glycation End-products, or AGEs, just a surrogate indicator).

There is one very important protein that is subject to glycation: Apoprotein B.

Apoprotein B, or Apo B, is the principal protein of VLDL and LDL particles. Because there is one Apo B molecule per VLDL or LDL particle, Apo B can serve as a virtual VLDL/LDL particle count. The higher the Apo B, the greater the number of VLDL and LDL particles.

Because Apo B is a protein, it too is subject to the process of glycation. The interesting thing about the glycation of Apo B is that its "glycatability" depends on LDL particle size: The smaller the LDL particle, the more glycation-prone the Apo B contained within.

Younis et al have documented an extraordinary variation in glycatability between large and small LDL, with small LDL showing an 8-fold increased potential.

Think about it: Carbohydrates in the diet, such as wheat products and sugars, trigger formation of small LDL particles. Small LDL particles are then more glycation-prone by up to a factor of 8. Interestingly, HbA1c is tightly correlated with glycation of Apo B. Diabetics with high HbA1c, in particular, have the greatest quantity of glycated Apo B. They are also the group most likely to develop coronary atherosclerosis, as well as other consequences of excessive AGEs.

No matter how you spin it, the story of carbohydrates is getting uglier and uglier. Carbohydrates, such as those in your whole grain bagel, drive small LDL up, while making them prone to a glycating process that makes them more likely to contribute to formation of coronary atherosclerotic plaque.

High HbA1c: You're getting older . . . faster

28. March 2010 William Davis (16)
Over the years, we all accumulate Advanced Glycation End-products, or AGEs.

AGEs are part of aging; they are part of human disease. AGEs are the result of modification of proteins by glucose. AGEs form the basis for many disease conditions.

Accumulated AGEs have been associated with aging, dementia, cataracts, osteoporosis, deafness, cancer, and atherosclerosis. Most of the complications of diabetes have been attributable to AGEs.

There's one readily available method to assess your recent AGE status: HbA1c.

Hemoglobin is the oxygen-carrying protein of red blood cells. Like other proteins, hemoglobin becomes glycated in the presence of glucose. Hemoglobin glycation increases linearly with glucose: The higher the serum or tissue glucose level, the more glycation of hemoglobin develops. Glycated hemoglobin is available as the common test, HbA1c.

Ideal HbA1c is 4.5% or less, i.e., 4.5% of hemoglobin molecules are glycated. Diabetics typically have HbA1c 7.0% or greater, not uncommonly greater than 10%.

In other words, repetitive and sustained high blood glucose leads to greater hemoglobin glycation, higher HbA1c, and indicates greater glycation of proteins in nerve cells, the lens of your eye, proteins lining arteries, and apoprotein B in LDL cholesterol particles.

If AGEs accumulate as a sign of aging, and high blood sugars lead to greater degrees of glycation, it only follows that higher HbA1c marks a tendency for accelerated aging and disease.

Indeed, that is what plays out in real life. People with diabetes, for instance, have kidney failure, heart disease, stroke, cataracts, etc. at a much higher rate than people without diabetes. People with pre-diabetes likewise.

The higher your HbA1c, the greater the degree of glycation of other proteins beyond hemoglobin, the faster you are aging and subject to all the phenomena that accompany aging. So that blood glucose of 175 mg/dl you experience after oatmeal is not a good idea. 

The lesson: Keep HbA1c really low. First, slash carbohydrates, the only foods that substantially increase blood glucose. Second, maintain ideal weight, since normal insulin responsiveness requires normal body weight. Third, stay physically active, since exercise and physical activity exerts a powerful glucose-reducing effect. Fourth, consider use of glucose-reducing supplements, an issue for another day.

While HbA1c cannot indicate cumulative AGE status, it can reflect your recent (preceding 60 to 90 days) exposure to this age-accelerating thing called glucose.

If your doctor refuses to accommodate your request for a HbA1c test, you can perform your own fingerstick test.

Slash carbs . . . What happens?

26. March 2010 William Davis (20)
Cut the carbohydrates in your diet and what sorts of results can you expect?

Carbohydrate reduction results in:

Reduced small LDL--This effect is profound. Carbohydrates increase small LDL; reduction of carbohydrates reduce small LDL. People are often confused by this because the effect will not be evident in the crude, calculated (Friedewald) LDL that your doctor provides.

Increased HDL--The HDL-increasing effect of carbohydrate reduction may require 1-2 years. In fact, in the first 2 months, HDL will drop, only to be followed by a slow, gradual increase. This is the reason why, in a number of low-carb diet studies, HDL was shown to be reduced.--Had the timeline been longer, HDL would show a significant increase.

Decreased triglycerides--Like reduction of small LDL, the effect is substantial. Triglyceride reductions of several hundred milligrams are not at all uncommon. In people with familial hypertriglyceridemia with triglyceride levels in the thousands of milligrams per deciliter, triglyceride levels will plummet with carbohydrate restriction. (Ironically, conventional treatment for familial hypertriglyceridemia is fat restriction, a practice that can reduce triglycerides modestly in these people, but not anywhere near as effectively as carbohydrate restriction.) Triglyceride reduction is crucial, because triglycerides are required by the process to make small LDL--less triglycerides, less small LDL.

Decreased inflammation--This will be reflected in the crude surface marker, c-reactive protein--Yes, the test that the drug industry has tried to convince you to take statins drugs to reduce. In my view, it is an absurd notion that you need to take a drug like Crestor to reduce risk associated with increased CRP. If you want to reduce CRP to the floor, eliminate wheat and other junk carbohydrates. (You should also add vitamin D, another potent CRP-reducing strategy.)

Reduced blood pressure--Like HDL, blood pressure will respond over an extended period of months to years, not days or weeks. The blood pressure reduction will be proportion to the amount of reduction in your "wheat belly."

Reduced blood sugar--Whether you watch fasting blood sugar, postprandial (after-meal) blood sugars, or HbA1c, you will witness dramatic reductions by eliminating or reducing the foods that generate the high blood sugar responses in the first place. Diabetics, in particular, will see the biggest reductions, despite the fact that the American Diabetes Association persists in advising diabetics to eat all the carbohydrates they want. Reductions in postprandial (after-eating) blood sugars, in particular, will reduce the process of LDL glycation, the modification of LDL particles by glucose that makes them more plaque-causing.


You may notice that the above list corresponds to the list of common plagues targeted by the pharmaceutical industry: blood pressure, diabetes (diabetes being the growth industry of the 21st century), high cholesterol. In other words, high-carbohydrate, low-fat foods from the food industry create the list of problems; the pharmaceutical industry steps in to treat the consequences.

In the Track Your Plaque approach, we focus specifically on elimination of wheat, cornstarch, and sugars, the most offensive among the carbohydrates. The need to avoid other carbohydrates, e.g., barley, oats, quinoa, spelt, etc., depends on individual carbohydrate sensitivty, though I tend to suggest minimal exposure.

Normal fasting glucose with high HbA1c

23. March 2010 William Davis (24)
Jonathan's fasting glucose: 85 mg/dl
His HbA1c: 6.7%

Jonathan's high HbA1c reflects blood glucose fluctuations over the preceding 60-90 days and can be used to calculate an estimated average glucose (eAG) with the following equation:

eAG = 28.7 X A1c – 46.7

(For glucose in mmol/L, the equation is eAG = 1.59 × A1C - 2.59)

What's that in your mouth?

7. January 2010 William Davis (17)



Fat = triglycerides

In other words, eat fat, whether it's saturated, hydrogenated, polyunsaturated, or monounsaturated, and blood levels of triglycerides will go up over the next 6 hours. This remains true if there are carbohydrates in the meal, or if there are NO carbohydrates in the meal. It also remains true if you chronically consume fats.

While fats are the primary determinant of postprandial (after-eating) triglycerides, carbohydrates are the primary determinant of fasting triglycerides.

So, if your triglycerides are high on a fasting cholesterol (lipid) panel, it's most likely because you overconsume carbohydrates.


Thanks to cartoonist Eli Stein, who has generously allowed me to reprint his artwork on these pages. Mr. Stein has published his work in dozens of magazines and newspapers, including the Wall Street Journal, Barron's, and Good Housekeeping. More of his work can be found at Eli Stein Cartoons.

De Novo Lipo-what?

5. January 2010 William Davis (16)
Humans have limited capacity to store carbohydrates. Beyond the glucose and glycogen in our blood and tissues, we have relatively little carbohydrate to draw from in time of energy need. That's why long-distance runners and triathletes have to carry sugar sources to keep blood sugar from plummeting.

Fat, of course, is different. We have virtually unlimited capacity to store energy as fat.

Because we have limited carbohydrate storage capacity, what can the body do with the excessive quantities of carbohydrates that Americans ingest? What becomes of a bagel for breakfast, wheat crackers for snacks, a whole wheat sandwich for lunch, pretzels, and whole wheat pasta that many people eat every day, not to mention the chips, soft drinks, and juices?

Excess carbohydrates are diverted to an interesting metabolic pathway called de novo lipogenesis (DNL). This refers to the liver's ability to make triglycerides from excessive carbohydrates in the diet. Triglycerides are packaged for release into the blood as VLDL. VLDL, in turn, interacts with other lipoproteins, creating small LDL particles, reduced HDL and smaller, less protective HDL. High VLDL will be measured on a standard cholesterol panel as higher triglycerides.

A University of California (Berkeley, San Francisco) group has done much of the work describing DNL.

A diet weighed towards carbohydrates, especially if 50% or greater calories are carbohydrate, is sufficient to provoke plenty of DNL, even in slender people. DNL is a big part of the reason why low-fat (and, thereby, high-carbohydrate) diets result in higher triglycerides. DNL really gets turned on many-fold if the carbohydrates are "simple," rather than "complex."

Overweight people, however, can demonstrate five-fold greater DNL even with lesser quantities of carbohydrate intake (e.g., 40% fat, 46% carbohydrate, 14% protein):





From Schwarz et al 2003. Mean (± SEM) fractional de novo lipogenesis in lean normoinsulinemic (NI), obese NI, and obese hyperinsulinemic (HI) subjects after 5 d of consuming a high-fat, low-carbohydrate diet and in different lean NI and obese HI subjects after 5 d of consuming a low-fat, high-carbohydrate diet. Values with different superscript letters are significantly different.


Excessive carbohydrates, a la standard low-fat diets, are good for nobody. The concept of de novo lipogenesis fills in a theoretical hole that now explains why people who eat carbohydrates have higher triglycerides, VLDL, and, eventually, insulin resistance and diabetes.

Gretchen's postprandial diet experiment II

3. January 2010 William Davis (37)
I previously posted Gretchen's postprandial diet experiment, in which she consumed a low-fat diet for a day, followed by a low-carbohydrate diet for a day. Grethen monitored blood glucose and triglycerides with fingerstick checks. (Blood glucose can be checked on any widely available glucose monitor; triglycerides can be monitored with the Cardiochek device.)

Let's now discuss what happened.

On the low-carb, high-fat day, there was an initial surge in triglycerides to 250 mg/dl late morning, followed by a secondary peak several hours following dinner. Because fat is mostly triglycerides, Gretchen's high-fat (sausage, bacon, butter, whole-fat yogurt) breakfast provided a large quantity of triglycerides that needed to be absorbed. This generally occurs over approximately 6 hours, varying depending on body weight, how accustomed you are to fat, activity level during the day, the kind of fat in the meal. The high content of saturated fat in Gretchen's high-fat breakfast likely caused the somewhat slower drop in triglycerides over approximately 7 1/2 hours.

As Gretchen herself had noted, triglycerides the following day were lower, a typical low-carb response. Blood sugar throughout showed only minor variation, with only small postprandial increases.

Thus, Gretchen experienced what we'd expect with a low-carb, high-fat diet: an initial high surge in triglycerides, followed by a decline in fasting levels, while blood sugar shows a normal contour.







Now, the more confusing low-fat experience:



Blood glucose makes a striking peak at 200 mg/dl after the low-fat breakfast of pasta and rice, in contrast to the low-carb breakfast. Triglycerides behaved very differently from the low-carb experiment: While there was no initial postprandial surge, there was a late surge developing 6-24 hours later. The late surge continued into the next day, with fasting levels the following morning (210 mg/dl) exceeding the starting triglyceride level (60 mg/dl).

The one potentially confusing aspect of all this is Gretchen's late rise in triglycerides on the low-fat diet. This phenomenon is due to something called de novo lipogenesis, or the liver's conversion of carbohydrates to triglycerides that occurs when an excessive carbohydrate load comes through diet. Because the human body cannot store anything beyond a minor quantity of carbohydrates (as glucose and glycogen), carbohydrates are converted to fats.

Another factor causing the late triglyceride increase is insulin resistance, given the high blood sugar response. When insulin resistance is present, the activity of the enzyme, lipoprotein lipase, is reduced. Less lipoprotein lipase activity allows slower VLDL degradation, allowing VLDL (and thereby triglycerides contained in VLDL) to "stack up" in the blood. Thus, the higher triglycerides late after eating and into the next morning.

One issue to be aware of: Acute responses can differ from chronic responses. In other words, had Gretchen had the luxury (and time and money) to conduct the experiment over, say, 4 weeks, rather than a single day, there would be somewhat different responses. The best data on this come from Dr. Jeff Volek of the University of Connecticut, in which 4 weeks of low-carbohydrate eating modify fasting and postprandial responses over time.

Several conclusions can be made from Gretchen's experience:

1) Low-carb, high-fat acutely generates extravagant postprandial triglyceride responses.
2) Low-fat causes a late triglyceride surge and higher fasting triglycerides.
3) Low-fat leads to high blood sugars and, by implication, diabetes.


Both the low-carb and the low-fat responses are undesirable, both leading to increased risk for heart disease. Which is worse? I believe that low-fat is more destructive, since it leads over time to both high triglycerides and diabetes, while low-carb/high-fat only leads to postprandial triglyceride surges, at least acutely.

How to best balance the responses to reduce risk for heart disease? That's a discussion for future.


Again, my thanks to Gretchen and the substantial amount of effort that went into generating these numbers. More of Gretchens' own writing can be found on her blogs:
http://wildlyfluctuating.blogspot.com
http://www.healthcentral.com/diabetes/c/5068

A wheat-free 2010

2. January 2010 William Davis (22)
A Heart Scan Blog reader sent this fascinating description of his wheat-free adventure.

Whenever I discuss this notion of going wheat-free and the incredible health effects that develop, I invariably receive comments or emails saying something like "I eat wheat and feel fine. That can't be true." The problem is that not everybody needs to go wheat-free. 20-30% of people can include wheat in their diet and suffer little more than weight gain, some not at all.

But stories like Michael's (below) are commonplace in my experience. I've had many patients who, at first, refused to believe that wheat exposure might be the underlying cause for health struggles. But they finally give it a try and find that rashes, arthritis, acid reflux, irritable bowel symptoms, mood swings, anger, etc. are miraculously improved or gone.

Anyway, hear what Michael has to tell us:


Dr. Davis,

I want to thank you. I was browsing the web a while back and happened to stumble upon your blog post about wheat belly. The first thing that caught my attention was that I thought you had somehow gotten a photograph of me. The young man you posted an image of looked exactly like me. So I read what you had to say. After reading, I thought "Four weeks isn’t so bad. I think I can handle this."

It has now been nine weeks and all I can say is that I am completely amazed. Let me say first that twice in the past twenty years I have been tested for allergies. The first time I was tested I showed a slight reaction to Timothy Grass, but not enough to cause me any problems. The second testing I did not show a reaction to anything. So, I have always assumed that my chronic sinus problem were due to sensitivities to environmental pollutions. Now I am not so sure. I would like to list for you everything that has happened to me since I eliminated wheat from my diet.

1. I have lost a total of 12 pounds in the last 9 weeks.
2. I have lost 1 ¼ inches of belly fat
3. I have lost a tremendous amount of fat from my neck.
4. My entire life I have had problems with oily hair. I could wash my hair and three hours later I looked as if I hadn’t washed in a week. Now my hair stays clean and soft for two to three days without shampoo.
5. My hair was always flat and stringy. Now it has lots of body.
6. I used to have thick layers of dry skin on my scalp. It would come loose in chunks as large as a fingernail. That dry scalp is gone.
7. I used to have dry flaky skin that seemed to secrete oil. That no longer happens. My skin is now soft and smooth.
8. I have lived with bad acne for at least 35 years. Now it is hard to find a pimple on my body.
9. I have always had to fight dehydration. That is no longer a problem.
10. I used to drink two large cups of coffee every morning just to be able to function. I now have enough energy that I have eliminated caffeine from my diet.
11. I sleep more soundly than ever before and my dreams are clear and vivid.
12. My thought processes are more active and clear than they have ever been.
13. My chronic sinus issue is now a thing of the past.
14. I used to have problems with getting the “shakes” if I had gone more than a couple of hours without eating. It was as if I was suffering from low blood sugar. I would even be afraid that I would pass out. Now all I feel is hunger. I can go all day without eating and never feel in danger of losing consciousness.


Today is Thursday. This past Monday my wife and I were eating out and I ordered a burger without a bun. What I didn’t realize was that the burger would arrive covered in onion rings. I knocked the mountain of onion rings onto the plate but there were still a couple that were embedded in the cheese. I decided, what the hell, a couple of onion rings shouldn’t make that much of a difference. I will not make that mistake again anytime soon. Within 30 m