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There was a little girl, Who had a little curl, Right in the middle of her forehead When she was good She was very good indeed But when she was bad she was horrid.
So goes the familiar poem by Henry Wadsworth Longfellow, and so goes most of our low-carb diets I suspect. When we are in diet mode and are deeply committed, we are very good indeed, but when we break and hit the carbs (and this includes yours truly) we are horrid. A paper in this week’s JAMA presents data confirming what I’ve long suspected: carb bingeing now and then could actually cause worse free radical damage than regularly eating more carbs on an ongoing basis.
The paper entitled shows that patients with diabetes who have fluctuations in their blood sugars incur more free radical damage than those with high but not fluctuating blood sugar levels. Before we get into the nitty gritty of the paper, I will step back a little and go over some of the biochemistry involved so that the data will be more understandable to those who might not have a technical background.
First, let’s look at how blood sugar is measured. The standard way is to draw blood (usually after the patient has fasted for 12-14 hours) and test it for a blood sugar level. Although this is the way that diabetics were monitored for years, it’s not a particularly accurate means of managing patients with diabetes. The fasting blood sugar test itself is reliable, but it only tells what the blood sugar is at the precise moment the blood was drawn–not what it was the week before or the day before or even the hour before. The typical drill was that diabetic patients would come to the office, have their blood sugar levles checked, and based on the results, leave with their medications or insulin adjusted as necessary. Many diabetic patients who didn’t like getting lectured by their doctors on following the proper diet, exercising, etc., learned that if they were very good indeed for the few days before their office visit, their blood sugar levels would be close to normal. They would leave
Following a low-carb diet makes one a little glucose intolerant, which is the reason that the instructions for a glucose tolerance test always include the admonition to eat plenty of carbs in the week before the test. Why? Because all the macronutrients–glucose, fat and protein–are broken down by enzymes during the metabolic process. And all the enzymes necessary for the metabolism of the various macronutrients are made on demand but not immediately. If you are on a high carbohydrate diet, then you will have plenty of enzymes on hand to deal with the carbohydrates you consume. If you switch to a low-carbohydrate diet, it takes a while to manufacture the enzymes in the quantities needed to deal with the extra fat and protein that your metabolic system hadn’t been exposed to. This deficiency of protein/fat metabolizing enzymes is the reason people starting a low-carb diet become so easily fatigued–they’ve got plenty of enzymes on hand to break down carbs, they just don’t have the carbsto metabolize. Once they produce the enzymes necessary to deal with the load of protein and fat, which takes a few days, they become low-carb adapted and no longer feel fatigued.
Once people become low-carb adapted–as I hope we all are–then the same thing happens if they go face down in the donuts. They don’t have the enzymes on board to deal with the sudden influx of glucose, and, as a consequence, their blood sugar spikes higher than it would on a person eating the same amount of carbohydrate who is already carb adapted.
This paper shows that these carb spikes are not benign. As the paper points out
Risk factors of atherosclerosis such as hypertension, regular smoking, hyperlipidemia, and obesity have been described as being associated with elevated urinary excretion rates of isoprostanes.
Since the best thing we can do for ourselves is limit free radical damage as much as possible, the obvious way to do so is to maintain a constant low level of blood sugar, for which the low-card diet is just the ticket. In view of these recent findings when we’re good, we should be very good indeed, but when we’re bad maybe we shouldn’t be quite so horrid.
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