Why Diabetics Should Avoid High Carbohydrate Diets.

American Diabetes Association's Bizarre Message to Diabetics: "A High Carbohydrate Diet Will Raise Your Blood Sugar - But You Should Eat it Anyway!"

By Anthony Colpo.

March 28, 2004.

Among the influential mainstream proponents of low-fat nutrition is the American Diabetes Association who, for years, has recommended that diabetics consume a high-carbohydrate diet.

Never mind that diabetes is an illness characterized by glucose intolerance; that is, an inability to efficiently metabolize dietary carbohydrates which, regardless of their source (complex, simple, high-glycemic, low-glycemic, high-fiber, low-fiber) are ultimately broken down into glucose inside the body. In healthy individuals with optimal glycemic control, much of this glucose will be channeled into the muscles (and to a lesser extent, the liver), where it will be stored as glycogen. This stored glycogen can later be used as fuel for muscular effort.

In healthy individuals, the transport of glucose from the blood into the muscles is largely mediated by insulin, a hormone secreted by the pancreas. By removing glucose from the bloodstream into muscles, insulin helps keep blood sugar levels in a tightly-controlled range. This is important, because both low and high blood sugar levels have a number of adverse physiological consequences, and epidemiological studies have uncovered a higher risk of cardiovascular and all-cause mortality for individuals with hypoglycemia (low blood glucose) and hyperglycemia (high blood glucose).(Bjornholt JV)(Wei M)

In full-blown diabetics, a lack of sufficient insulin output by the pancreas leads to chronically elevated high blood sugar levels. The resultant hyperglycemia dramatically increases glycation, a process in which protein and sugar molecules in the body "cross-link", forming what are known as advanced glycation end-products (AGEs). Glycation is a process to which none of us are immune, but it can be reduced by avoiding high-glycemic load diets and by minimizing our intake of overcooked, highly-browned foods.

Glycation damages our organs and tissues and, along with free radical damage, is considered a major contributor to the aging process. It is no coincidence that diabetics typically have significantly-shortened lifespans compared to non-diabetics, along with a far higher prevalence of heart disease, cancer, kidney disease, amputation, and blindness.

Listen to the ADA - and watch your blood sugar go up!

Recently, I received a copy of a highly-informative and soon-to-be-published review on popular low-carbohydrate diet books, which had kindly been forwarded to me by its author. As I scanned through the review, my eyes nearly popped out after reading the following quote, attributed to the American Diabetes Association:

"The message today: Eat more starches! It is healthiest for everyone to eat more whole grains, beans, and starchy vegetables such as peas, corn, potatoes and winter squash. Starches are good for you because they have very little fat, saturated fat, or cholesterol. They are packed with vitamins, minerals, and fiber. Yes, foods with carbohydrate -- starches, vegetables, fruits, and dairy products -- will raise your blood glucose more quickly than meats and fats, but they are the healthiest foods for you. Your doctor may need to adjust your medications when you eat more carbohydrates. You may need to increase your activity level or try spacing carbohydrates throughout the day."

Reeling in disbelief at the stupidity of such advice, I visited the ADA website (March 28, 2004), and sure enough, in an article titled The Diabetes Food Pyramid: Starches, were the very words you see printed above.

The complete lack of logic in the ADA's statement is absolutely mind-boggling. We are simultaneously told that "Yes, foods with carbohydrate -- starches, vegetables, fruits, and dairy products -- will raise your blood glucose more quickly than meats and fats" - a situation to be avoided at all costs by diabetics - but that these high-carbohydrate foods "are the healthiest" for diabetics. How can that be?

The consequences of the ADA's enthusiastic call to "Eat more starches!" are alluded to in the sentence that states: "Your doctor may need to adjust your medications when you eat more carbohydrates." Yes, if your blood sugar rises from eating more carbohydrates, your doctor will indeed need to adjust your diabetic medication dosage - upwards!

The ADA article also states that: "You may need to increase your activity level or try spacing carbohydrates throughout the day", further acknowledging the deleterious glycemic effects of increased carbohydrate intake.

Why in blazes is America's premier diabetes organization recommending a diet that will raise blood sugar levels and necessitate increases in blood-sugar lowering drugs? And, even worse, why are they actively discouraging diabetics from trying the very diets that have been shown repeatedly to improve glycemic control? I'm talking about carbohydrate-reduced diets. Take the following quote:

"Currently some controversy about carbohydrates is raging due to a few new diet books. These books encourage a low carbohydrate, high protein and moderate fat intake. These diets are not in synch with the American Diabetes Association nutrition recommendations, which are based on years of research and clinical experience."

The ADA is 100% correct that low-carb diets are not in synch with their own recommendations; given the highly erroneous and counterproductive nature of the ADA recommendations, this cannot be considered anything but a virtue!

The ADA claims that their nutrition recommendations "...are based on years of research and clinical experience". If they are implying that science supports their guidelines as being beneficial to diabetics, nothing could be further from the truth. As we shall now discuss, numerous studies show that high-carbohydrate diets can markedly worsen glycemic control in both diabetic and even non-diabetic individuals. Reduced-carbohydrate diets, on the other hand, can bring about dramatic improvements in glycemic control.

What the Research Shows

When Type 2 diabetics were placed on a low carbohydrate diet (25% carbohydrate) for 8 weeks, they experienced significant improvements in glycemic control, as reflected by decreases in both fasting blood glucose and hemoglobin A1c, a measurement that reflects the average blood sugar level over the previous 3 months or so. Nineteen of the patients had been taking oral diabetic drugs prior to the onset of the study; all were able to discontinue the use of these drugs during the study. However, when the patients were switched to a 55% carbohydrate diet - similar to that recommended by the ADA - their blood glucose control and hemoglobin A1c measurements significantly deteriorated. (Gutierrez et al. 1998)

Similar results were noted in a 1987 study which also compared higher and lower carbohydrate intakes in Type 2 diabetics. In this study, one of the diets contained 20 percent protein, 20 percent fat, and 60 percent carbohydrate, again similar to that recommended by the ADA. The other contained 20 percent protein, 40 percent fat, and 40 percent carbohydrate. Unfavorable glucose and insulin responses, and significantly greater 24-hour urinary glucose excretion, were observed when subjects followed the high carbohydrate diet. (Coulston et al. 1987)

A 1994 edition of the Journal of the American Medical Association reported how Type 2 diabetics consumed a 40% carbohydrate, 45% fat diet for 6-14 weeks, and a 55% carbohydrate, 30% fat diet for another 6-14 weeks in a randomized crossover fashion. The high carbohydrate diet increased daylong blood glucose and insulin values by 10%. (Garg et al. 1994)

Yet another study with Type 2 diabetics showed that raising the dietary carbohydrate content by a mere 10%, from 40% to 50%, resulted in a significant increase in both post-meal blood glucose and insulin concentrations. (Sestoft et al. 1985)

Finally, researchers from the University of Minnesota recently found that Type 2 diabetics consuming a 30 percent protein, 30 percent fat, and 40 percent carbohydrate diet (a macronutrient ratio similar to that prescribed in Dr. Barry Sear's Zone Diet), showed significantly lower blood glucose levels after meals and greater reductions in glycated hemoglobin levels than those following a 15 percent protein, 30 percent fat, and 55 percent carbohydrate diet. (Gannon et al.)

Type 2 diabetics are not the only folks who experience improvements in blood sugar metabolism when carbohydrate intake is restricted. A recent study compared the effects of three different diets in healthy volunteers; 1) zero fat, high carbohydrate, 2) moderate fat, moderate carbohydrate, and 3) high fat, low carbohydrate. Researchers observed significantly lower insulin concentrations on the high fat, low carbohydrate diet. In addition, those on the high fat, low carbohydrate diet burnt more fat and less glucose for fuel. (Bisschop et al. 2001)

To be fair, high carbohydrate diets can lead to improvements in blood sugar and insulin function if caloric intake is restricted to the point where fat loss occurs, but the ADA does not include this important pre-requisite in their dietary guidelines.

Furthermore, when calorie-reduced low-fat, high-carbohydrate regimens are directly compared with similarly-restricted low carbohydrate diets, the latter are still shown to be more effective in terms of glycemic control. (Baba et al. 199)Brehm et al. 2003)(Lewis et al. 1977)(Volek et al. 2002)(Layman et al. 2003)(Farnsworth et al. 2003)(Heilbronn et al. 1999)(Jeppesen et al. 1997)(Gumbiner et al. 1996)(Golay et al. 1996)(Piatti et al. 1994)(Rabast et al. 1979)(Fujita et al. 1975)

Finally, while calorie-restriction may help mitigate the harmful glycemic effects of high carbohydrate diets, what happens when diabetic individuals eventually return to maintenance-calorie intakes? If the studies comparing maintenance-calorie high- and low-carb diets that we discussed above are any indication, the result will be steadily deteriorating glucose tolerance.


The research leaves little doubt as to what diabetics can expect from the American Diabetes Association's bizarre "a-high-carbohydrate-diet-will-raise-your-blood sugar-but-you-should-eat it-anyway" message: worsening glycemic control! Because it is poor glycemic control that causes the health problems that befall diabetics - not imaginary villains like saturated fat or cholesterol - diabetics would be very wise to disregard the contradictory, incoherent, and scientifically baseless recommendations of the ADA.


Bjornholt JV, et al. Fasting blood glucose: an underestimated risk factor for cardiovascular death. Results from a 22-year follow-up of healthy nondiabetic men. Diabetes Care, 1999; 22: 45-49.

Wei M, et al. Low Fasting Plasma Glucose Level as a Predictor of Cardiovascular Disease and All-Cause Mortality. Circulation, May, 2000; 101: 2047-2052.

Gutierrez M, et al. Utility of a Short-Term 25% Carbohydrate Diet on Improving Glycemic Control in Type 2 Diabetes Mellitus. Journal of the American College of Nutrition, 1998; 17 (6): 595-600.

Coulston AM, et al. Deleterious metabolic effects of high-carbohydrate, sucrose-containing diets in patients with non-insulin-dependent diabetes mellitus. American Journal of Medicine, 1987 Feb; 82 (2): 213-20.

Garg A, et al. Effects of varying carbohydrate content of diet in patients with non-insulin-dependent diabetes mellitus. Journal of the American Medical Association, 1994; 271: 1421-1428.

Sestoft L, et al. High-carbohydrate, low-fat diet: effect on lipid and carbohydrate metabolism, GIP and insulin secretion in diabetics. Danish Medical Bulletin. 1985 Mar; 32 (1): 64-69.

Gannon MC, et al. An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes. American Journal of Clinical Nutrition, 2003; 78: 734-741.

Bisschop PH, et al. Dietary fat content alters insulin-mediated glucose metabolism in healthy men. American Journal of Clinical Nutrition, 2001; 73: 554-559.

Baba NH, et al. High Protein vs High Carbohydrate Hypoenergetic Diet for the Treatment of Obese Hyperinsulinemic Subjects. International Journal of Obesity, 1999; 11: 1202-1206.

Brehm BJ, et al., A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women. The Journal of Clinical Endocrinology and Metabolism, 2003; 88 (4): 1617-1623.

Lewis SB, et al. Effect of Diet Composition on Metabolic Adaptations to Hypocaloric Nutrition: Comparison of High Carbohydrate and High Fat Isocaloric Diets. The American Journal of Clinical Nutrition, 1977; 30 (2): 160-170.

Volek JS, et al. Body Composition and Hormonal responses to a Carbohydrate Restricted Diet. Metabolism, 51(7), 2002, pages 864-870.

Layman DK, et al. Increased Dietary Protein Modifies Glucose and Insulin Homeostasis in Adult Women during Weight Loss. The Journal of Nutrition, 2003; 133 (2): 405-410.

Farnsworth E, et al. Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women. American Journal of Clinical Nutrition, July 2003; 78: 31-39.

Heilbronn LK, et al. Effect of Energy Restriction, Weight Loss, and Diet Composition on Plasma Lipids and Glucose in Patients With Type 2 Diabetes. Diabetes Care, 1999; 22 (6): 889-895.

Jeppesen J, et al. Effects of low-fat, high-carbohydrate diets on risk factors for ischemic heart disease in postmenopausal women. The American Journal of Clinical Nutrition, 1997; 65 : 1027-1033.

B Gumbiner, et al. Effects of diet composition and ketosis on glycemia during very-low- energy-diet therapy in obese patients with non-insulin-dependent diabetes mellitus. The American Journal of Clinical Nutrition, 1996; 63: 110-115.

Golay A, et al. Similar weight loss with low- or high-carbohydrate diets. The American Journal of Clinical Nutrition, 1996; 63: 174-178.

Piatti PM, et al. Hypocaloric high protein diet improves glucose oxidation and spares lean body mass. Comparison to hypocaloric high-CHO diet. Metabolism, Dec. 1994; 43 (12): 1481-1487.

Rabast U, et al. Dietetic treatment of obesity with low and high carbohydrate diets: Comparitive studies and clinical results. International Journal of Obesity, 3 (3), 1979, pages 201-211.

Fujita Y, et al. Basal and postprotein insulin and glucagon levels during a high and low carbohydrate intake and their relationships to plasma triglycerides. Diabetes, 1975; 24 (6): 552-558.

Anthony Colpo is an independent researcher and certified fitness consultant with 20 years' experience in the physical conditioning arena. To contact: contact@theomnivore.com

Disclaimer: This article is presented for information purposes only and is not intended as medical advice. Persons with medical conditions should institute dietary changes whilst being monitored by a competent medical practitioner.

Anthony Colpo 2004.  http://www.theomnivore.com


see: Dr Bernstein's Diabetes Revolution


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