The Carbohydrate Conundrum
Julian Whitaker, MD
The diet and weight loss industry is booming. Everywhere you turn, there’s one gimmick or another guaranteed to melt the pounds away. From billboards and magazines to TV and radio ads, you can’t escape the promises of the latest and greatest. Trying to figure out what works and what doesn’t is enough to drive you crazy.
Folks, forget about low-fat this, carb-free that, and diets that require rocket science-level math to compute portion sizes and caloric intake. There’s an easy way to eat your way to health and fitness.
Carbohydrates are your body’s primary source of energy. As they are digested and released into the bloodstream as glucose, they signal cells in the pancreas to produce insulin, which escorts glucose into the cells, where it is metabolized into energy.
According to conventional wisdom, carbohydrates are lumped into two main categories: simple and complex. Simple carbohydrates are so named because they contain only one or two simple sugars, such as sucrose or fructose. Starchy carbohydrates, comprised of long chains of sugars, are considered complex. The old school of thought figures simple carbs are bad and should only be eaten in limited quantities, while complex carbs are given carte blanche since, in theory, they have less of an impact on blood sugar levels.
Turns out, it’s much more complicated than this. We now know that the effect carbohydrate foods have on blood sugar goes far beyond the old simple-complex model. Starchy complex carbohydrates such as potatoes and rice rapidly drive up blood sugar levels like “simple” carbs, while the blood sugar effects of the “complex” carbs in grains are dependent on factors such as particle size. For example, whole oats behave quite differently than instant oatmeal. This is why a preferred method of evaluating carbohydrate foods based on the glycemic index (GI) has evolved.
Glycemic Index vs. Glycemic Load
The GI measures the degree to which carbohydrate-containing foods trigger a rise in blood sugar levels. (Proteins and fat have little effect on blood sugar.) Foods with a low GI provoke smaller, more sustained elevations and provide a nice, steady supply of glucose and energy. Foods with a high GI, however, prompt rapid blood sugar spikes, followed by equally dramatic plummets. If you’ve ever experienced a “food coma” a few hours after a carb-heavy meal, you now know why.
Building on this knowledge, Walter Willett, MD, professor at the Harvard School of Public Health, and colleagues took the concept of the GI and expanded it into something more practical: the glycemic load (GL). Simply put, GL takes into account quality and quantity. It is determined by both the GI of any given food, plus the amount of available, or net, carbohydrates (fiber excluded) in a standard serving.
The GL has revealed a few surprises: Some foods with a high GI actually have minimal effects on blood sugar levels when eaten in normal quantities, while others with a low GI are potentially problematic. For example, a large carrot and a cup of spaghetti have similar GIs. Yet that carrot contains only 5 grams of available carbs (it’s mostly water), while the spaghetti contains 38 grams, giving them GLs of 2 and 16, respectively. Therefore, they have dramatically different effects on blood sugar. Carrots, watermelon, pineapple, and other fruits with a high GI once thought to be inappropriate for those minding their glucose levels turn out to be acceptable, while the GL confirms the need to go easy on pasta, bagels, and other starchy, carbohydrate-dense foods.
|Food||Glycemic Index(GI)||Serving Size||Glycemic Load(GL)|
|Rye Pumpernickel Bread||41||1 large slice||5|
|Kidney Beans||28||1 cup||7|
|Flour Tortilla||30||1 medium||8|
|All-Bran Cereal||38||1 cup||9|
|White Bread||70||1 slice||10|
|Ice Cream||61||1 cup||10|
|Low-Fat Yogurt||33||1 cup||16|
|Raisins||62||1 small box||20|
|Vanilla Cake With Frosting||42||1 small slice||24|
|Plain Bagel||72||1 small||25|
|Baked Potato||85||1 medium||28|
|Potato Chips||54||4 oz.||30|
|Macaroni and Cheese||64||1 serving||30|
|Snickers Bar||55||1 bar||35|
|This chart has been modified with permission from www.mendosa.com, with additional information from www.nutritiondata.com/glycemic-index.html.|
|Glycemic Index||Glycemic Load|
|Low||55 or under||10 or under|
|High||70 or above||20 or above|
The Benefits of a Low GI/GL Diet
Hundreds of studies on the effects of a low GI or GL diet have been conducted, most of them focused on diabetes. One typical study, a meta-analysis of clinical trials involving more than 350 diabetic patients, revealed that a low GL diet improved both long- and short-term management of blood sugar levels. But eating low GL carbs has other benefits as well.
A large, multi-year study by Harvard researchers found that overweight women who ate a high GL diet were twice as likely to develop coronary heart disease as their thinner counterparts who consumed low GI foods. High GL diets are also linked to increased risk of diabetes, gallbladder disease, and elevations in triglycerides, cholesterol, and C-reactive protein (a marker of inflammation implicated in a number of diseases). The GI/GL may also play a key role in weight loss. To date, 15 published studies demonstrate that when people eat foods with a low GI, they feel full longer and end up eating less.
Lighten Your Load
At my clinic, we strive to lighten our patient’s glycemic load. Our chef, who prepares three meals a day for patients attending our Back to Health Program, serves only low GL carbohydrates. That includes lots of salads, green vegetables, beans, and legumes. We go easy on breads, and for sweet treats we opt for fruit and occasional desserts made with low GL natural sweeteners, such as stevia and xylitol.
Of course, the glycemic load is not the only consideration in a healthful diet. White sugar has a low GL, but that doesn’t mean it’s good for anything. And don’t let the GL lull you into overeating: You still need to be mindful of calories and portion control. In addition to healthy carbs, the Whitaker Wellness dietary program also includes modest amounts of healthy fats and moderate portions of protein with each meal. This aids in blood sugar control for our diabetic patients and also helps with weight loss. A recent study conducted at the University of Illinois confirmed that a protein-rich diet, in conjunction with exercise, is more effective at reducing body fat than a diet low in calories alone.
I’ve personally taken this research to heart: One of my favorite meals is a hearty salad with a nice piece of salmon on top. It’s an easy way to get a tasty serving of healthy fats, plenty of protein, and lots of low GL carbs.
- To learn more, read my book The Whitaker Wellness Weight Loss Program,available in bookstores, online, or by calling (800) 810-6655.
- To learn more about the Whitaker Wellness Institute Therapeutic Lifestyle Changes (TLC) Program, contact a Patient Services Representative at (866) 944-8253 or click here.
- Oh K, et al. Carbohydrate intake, glycemic index, glycemic load, and dietary fiber in relation to risk of stroke in women. Am J Epidemiol. 2005 Jan 15;161(2):161-9.
Modified from Health & Healing with permission from Healthy Directions, LLC. Photocopying, reproduction, or quotation strictly prohibited without written permission from the publisher. To subscribe to Health & Healing, click here.