Carbohydrate-restriction diets remain controversial. In the classic Atkins diet, anything goes as long as it's not a carbohydrate - eating lard with a tablespoon would be quite an acceptable bedtime snack under the old-fashioned Atkins program. More moderate diets, like the South Beach diet(and more recent versions of Atkins) permit many carbohydrates that are absorbed slowly, and instead these diets restrict mainly the "fast" carbohydrates (i.e., the high-glycemic carbohydrates.) The high-glycemic carbs are absorbed rapidly into the blood stream, leading to wide fluctuations in blood glucose - and subsequently insulin - levels. It is the swings in insulin levels, the low-carb gurus insist, that lead to obesity. Restricting carbohydrates (or at least the high-glycemic carbs) keeps insulin levels low and aids in losing excess fat.
While recent clinical trials have added ammunition to the low-carb argument, the "nutrition establishment," having spent decades convincing us that restricting fats is the thing to do and that carbohydrates are benign, continues to insist that carb restriction is at least unnecessary, and possibly dangerous.
Now, investigators from Harvard Medical School have produced dramatic evidence in an animal model that high-glycemic carbs can lead to obesity and high cardiovascular risk. In their study, published in a recent issue of Lancet, they fed rats and mice two different diets. Each diet contained identical nutrients, but some received high-glycemic carbs and some received low-glycemic carbs. The animals fed a high-glycemic diet developed twice the body fat compared to low-glycemic animals over an 18-week period. They also developed elevated blood glucose levels, high triglycerides and reduced insulin sensitivity. (For those of you who are paying attention, this complex of metabolic abnormalities is the same that we have seen is responsible for metabolic syndrome.)
DrRich Comments:
While admittedly rats and mice are not humans, this study demonstrates that, at the least, the physiology claimed by low-carb proponents appears correct.
So what will happen now? Data accumulating from this study and others ultimately will force reluctant researchers to conduct similar studies in humans. In a decade or so, it is likely that enough evidence will be available that various professional bodies will ultimately endorse a low-glycemic lifestyle. So, we can wait for the evidence to push the nutrition establishment to change. Or, we can cut out the high-glycemic foods from our diet right now.
DrRich is normally strongly in favor of waiting for definitive proof before endorsing change. But here, he finds little to lose by beginning today to restrict things like simple sugars, potatoes, white rice, or white flour from our diet in favor of whole wheat, fruits and vegetables.
