Can We Stop Worrying About the Glycemic Index?
For years, we’ve been told to avoid high-glycemic foods. Now, a new study shows that it may not make much difference. Of course, there is a catch. Nutrition Diva explains.
I started my career in nutrition at about the same time as people starting talking about the glycemic index. At the time, it was a fairly radical new idea: that carbohydrate-containing foods could be described according to how fast your blood sugar rises after you eat them.
Low-glycemic carbs (sometimes referred to as “slow” carbs) are foods that cause a relatively low or slow increase in blood sugar. Low glycemic carbs include foods like non-starchy vegetables, beans, legumes, and whole grains. High-glycemic or “fast” carbs, which include things like soda, fruit juice, refined grains, and sweets, do just the opposite. Foods that cause a quick rise in blood sugar, it was theorized, would lead to reduced insulin sensitivity, increased fat storage, and an elevated risk of Type 2 Diabetes and obesity.
See also: What Is High Glucose?
Since then, the idea that we should limit high-glycemic foods has become completely mainstream, endorsed by everyone from the Harvard School of Public Health to the Nutrition Diva herself.
But as the years have rolled on, research on the benefits of low-glycemic diets has been surprisingly mixed. Did we all jump on the glycemic band-wagon too quickly? Does glycemic index not matter as much as we thought? Let’s find out.
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The More Carbs You Eat, the More the Glycemic Index Matters
A new study adds an interesting new twist to the carbohydrate conversation—one that may help explain why low-glycemic diets don’t always produce the kind of results we think they should. In this study, researchers demonstrated that if you’re limiting the amount of carbs you eat, it doesn’t matter that much whether you choose high or low glycemic carbs. But the more carbohydrates you eat, the more important it is to choose low glycemic foods.
If you’re only having 1 or 2 servings of grains a day and you want to have white pasta or French bread, you have my blessing.
I’ve made a similar argument before about grains: While whole grains are a more nutritious choice, portion size is more important than whether you’re eating whole grains or refined grains.
If you’re only having 1 or 2 servings of grains a day and you want to have white pasta or French bread, you have my blessing. If you’re eating 6-9 servings of grains a day, as recommended by the USDA (a recommendation that I find utterly absurd, by the way), you’d better make sure that they are low-glycemic.
See also: The Truth about Whole Grains
The subjects in this most recent study were all eating lots of fruits and vegetables and hardly any processed food. You could argue, therefore, that these results wouldn’t apply to the general population, because most people aren’t eating their fruits and vegetables and are eating lots of processed foods.
I’d argue, however, that this makes the study extra applicable to those of you listening to this podcast!
Why I Still Recommend Low-Glycemic Foods
Even if the glycemic index isn’t quite as important as we thought, low-glycemic carbs are usually more nutrient dense .
You’ve heard me say before that slow-burning carbs like beans, vegetables, whole fruit, whole grains, and so on, are preferable to high-glycemic carbs, such as sugar sweetened beverages, fruit juice, white bread and other refined grains. And I still think they are. Even if the glycemic index isn’t quite as important as we thought, low-glycemic carbs are usually more nutrient dense than high-glycemic carbs. They also tend to be higher in fiber, which has a variety of benefits, including appetite control.
But let’s face it: Sometimes a meal calls for fluffy white rice or satiny white bread instead of nubby whole grains. For that matter, I’ve never found whole wheat pita or tortillas to be quite as good as ones made with white flour. The good news is that these foods—in limited quantities—won’t torpedo an otherwise healthy diet.
As long as you’re eating lots of veggies and other nutritious foods, and you’re not going overboard with sweets or grain-based foods, you have my permission to relax about the glycemic index.
For more tips on how to make healthy and delicious choices at the grocery store and in your kitchen, check out my book Nutrition Diva’s Secrets for a Healthy Diet.
References
Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation. Nutr Rev. 2001 May;59(5):129-39.
Kristo AS, Matthan NR, Lichtenstein AH. Effect of diets differing in glycemic index and glycemic load on cardiovascular risk factors: review of randomized controlled-feeding trials. Nutrients. 2013 Mar 28;5(4):1071-80.
Roberts SB. Glycemic index and satiety. Nutr Clin Care. 2003 Jan-Apr;6(1):20-6.
Sacks FM, Carey VJ, et al. Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial. JAMA. 2014 Dec 17;312(23):2531-41.
Venn BJ, Green TJ. Glycemic index and glycemic load: measurement issues and their effect on diet-disease relationships. Eur J Clin Nutr. 2007 Dec;61 Suppl 1:S122-31.
About the Author
Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes’ most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation’s leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.
