Nutrition Counseling

Rethinking the Glycemic Index

I get questions all the time from my patients about the glycemic index (GI), especially from those working with me to achieve weight loss and manage their diabetes. This tool has been around for more than 40 years and remains controversial. I don’t believe it’s useful for helping my patients plan meals that meet their individual needs, and I think it actually can cause confusion about carbohydrates.

If you’re reading this and nodding your head, we’re not alone. According to a new survey of more than 750 Today’s Dietitian readers, sponsored by Potatoes USA, 73% of nutrition professionals who responded don’t use the GI when counseling clients and patients, and among those who did report using it, 70% don’t use it often.

Here are three things to keep in mind when addressing questions you may receive about the GI from your clients and patients.

1. There’s conflicting research on the GI of foods and its relationship to health.
The GI tells us nothing about the healthfulness or nutritional qualities of a food, beverage, or meal, and even when looking at the strongest intervention studies, it can’t accurately predict effects on overall health outcomes or disease risk. In fact, the 2010–2015 Dietary Guidelines Advisory Committee concluded that the GI isn’t associated with body weight and that limited evidence exists in support of a link between GI and CVD. Due to the lack of evidence supporting the GI for health outcomes, it’s unsurprising that an overwhelming majority (83%) of nutrition professionals reported that the GI isn’t part of the nutritional guidelines or standards for food and/or meal selection of patients in their professional place of practice.

2. The GI may cause your patients to eliminate perfectly healthful foods from their diet.
There’s a chance your patients may miss out on healthful, nutrient-dense foods if they choose them based solely on the GI. In fact, 3 out of 5 nutrition professionals surveyed strongly agree that eliminating high-GI foods from the diet and consuming only low-GI foods can cause people to exclude perfectly healthful foods from their diet. They also agree that the GI leads to misinformation about the healthfulness of fruits and vegetables. For example, potatoes, carrots, watermelon, and ripe bananas have GI scores categorized as “high,” and this score might lead to people excluding them from their diets. With only 1 in 10 Americans meeting recommendations for fruit and vegetable intake, confusion around their healthfulness in the context of the GI may be another barrier to adequate fruit and vegetable consumption.

3. The glycemic load (GL) isn’t a reliable alternative to the GI.
Because the GI doesn’t consider the amount of carbohydrates in a food when determining a score, the GL is sometimes considered to be a better indicator of how a carbohydrate food will affect blood sugar. This is because it combines both the quantity and quality of a carbohydrate-containing food, beverage, or meal. Considering the current evidence, the GI and GL may be less useful as overall measures of carbohydrate quality than dietary fiber and whole grain content. And 86% of nutrition professionals surveyed by Today’s Dietitian report they don’t use the GL with clients and patients.

When I’m working with clients who have diabetes, I believe it’s more practical to discuss the glycemic effect of a meal on blood sugar rather than focus on individual foods. I look at everything in terms of their individual carbohydrate needs and content at meals. It’s a breakthrough for my patients when they understand how the fiber, protein, or fat content of a meal impacts their blood sugar and then can prioritize those combinations on their own. I’m relieved when they understand they don’t need to be concerned about the GI of a single food.

I advise my patients to focus on the overall nutritional qualities of the food as they build their meals and snacks. Potatoes, for example, are a nutrient-dense vegetable and high-quality complex carbohydrate that provides 26 g carbs, 3 g plant-based protein, 27 mg vitamin C, and underconsumed nutrients including potassium (620 mg) and fiber (2 g) per 5.3-oz serving with skin. Potatoes make a great addition to a healthful, balanced plate.

It’s understandable that our patients, including those managing chronic health conditions, may be puzzled about the quality of their carbohydrates and the role of the GI in guiding their food selection to optimize health. Let’s work with them on other aspects of care and treatment that are less confusing and of higher priority than the GI to help them meet their health goals. Every one of our patients can and should enjoy all foods within a healthful diet without concern of their GI score.

— Constance Brown-Riggs, MSEd, RD, CDE, CDN, is past chair of the Diabetes Dietetic Practice Group of the Academy of Nutrition and Dietetics and author of the award-winning Diabetes Guide to Enjoying Foods of the World, a convenient guide to help people with diabetes enjoy all the flavors of the world while still following a healthful meal plan. Brown-Riggs is also a paid partner of Potatoes USA.

4 Comment

  1. Great insight Constance. This is exactly how I integrate GI into my practice. Even with so many controversies I have found it useful for my clients. I have even developed a toolkit that teaches RDs how to teach the GI concept to their patients because I find them focusing too much on the single food GI numbers rather than the cumulative effect.

    1. Thank you Alka. Yes, it’s so important to help our patients take the focus away from a single number of a single food and instead focus on nutrient-density of meals and snacks, helping them build a dietary pattern that works for them and meets their individual needs.

    2. Hello Alka, my name is Barbara Saulter; and I’m a RDN in private practice, as well as teaching nutrition at the community college level. Would you share with me the toolkit you developed teaching how to use the GI with patients? I would love to receive it.

      Thanking you in advance for responding to my request.

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