Opinion
(2007-10-08)
BRUSH, CO
(KUNC) -
You have my wife to thank for this commentary. I've been promising to review a study of weight loss diets for her. I figured I'd get some extra mileage for my efforts by reporting my findings to the KUNC audience too.
This year a pair of authors, writing for the Cochrane Collaboration, the premier American review of best medical practices, compared low-carbohydrate, low glycemic-index diets to the usual low calorie diets. Before I tell you what they found, let me explain about carbohydrates and glycemic index.
Sugar is the basic fuel for the cells of most plants and animals, including humans. Carbohydrates are molecules composed of sugars, including: single sugars, like glucose; pairs of sugars, like lactose; as well as longer sugar chains, (called starches) like amylose, which is simply a string of glucose molecules.
Digestive enzymes break carbohydrates down into their constituent sugar molecules. If you chew a saltine for a while amylase, an enzyme in your saliva, will immediately start working on the amylose starch in the cracker and you'll notice, if you can hold off a little while before you swallow, the sweet taste of glucose.
The digestive system takes more time to turn longer strings of carbohydrates into rapidly-absorbed sugars than it does to break down shorter strings. Also, the rate of absorption of the constituent sugars depends on the effectiveness of gut enzymes in uncoupling the specific chemical bonds that go into constructing each type of starch. Complex carbohydrates tend to be longer chains of sugars held together by links that are more resistant to digestion.
The harder a carbohydrate is to digest, the more slowly it is turned into simple sugar. Glycemic index is a measure of how much and how fast a body turns a carbohydrate in a food into sugar. Whole grains, nuts, most vegetables, and many fruits have a low glycemic index. Simple sugars, refined flour, potatoes and white rice are high glycemic index foods.
The higher the glycemic index of a carb, the bigger the resulting bump in blood sugar. The bigger the bump, the faster the rise of insulin to drive sugar from the bloodstream into cells. The faster the rise of insulin concentration in the blood and the more sugar that reaches the cells, the greater the tendency to gain weight.
Based on this physiology, the low glycemic index diet, designed to avoid fat-producing insulin spikes, has gained popularity. The Atkins and South Beach Diets are two of the best know incarnations of this strategy.
Proteins, fats and low-glycemic index carbs are the basis of such diets, which sometimes don't even try to restrict overall calories. Think of those news stories we saw a few years ago featuring people who ate bacon and eggs every day for breakfast and steaks for lunch and dinner and claimed to have dropped fifty or a hundred pounds. Losing weight on such a diet may sound impossible, but apparently it does work.
That's what the authors of the Cochrane report found. The six reputable studies reviewed had monitored two-hundred-and-two patients through five weeks to six months of dieting and for up to six months of post-dieting follow-up. The low-glycemic index dieters lost more weight and achieved lower LDL ( bad ) cholesterol levels than those who followed the usual low calorie diets. Calorie restriction tends to focus on reducing fat intake, because fat has the highest concentration of calories, and on reducing overall portion size of everything but vegetables.
So, the choice appears to be between being hungry most of the time versus eating about all you want, just so long as you stay away from simple carbohydrates. I consider it a privilege to deliver this good news to my wife, as well as to you.
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