Debunking the Glycemic Index — Registered Dietitian Columbia SC

Final week I listened to a current episode of Upkeep Part podcast the place they debunked frequent sugar myths, and it jogged my memory that I’ve been which means to do a weblog submit of my very own debunking the glycemic index. As a diet pupil in a really conventional dietetics program, there was lots that I realized that I’ve since needed to unlearn (ahem, just about all the pieces about ob*sity). However often there’s one thing that’s a part of mainstream diet discourse that even 15 years in the past after I was at school we realized was completely bunk. Glycemic index is a kind of matters! Though it’s one thing that makes intuitive sense, per standard, diet and our particular person biology is rather more advanced than some chart of what to eat and what to keep away from.

What’s the Glycemic Index?

The Glycemic Index (GI) was a software that was initially created within the Eighties by a researcher named David Jenkins to offer steering for selecting meals which have much less of an impact on blood sugar ranges. Jenkins developed the glycemic index by having analysis topics eat 50 grams price of carbohydrates from particular meals, measuring their blood sugar over the subsequent two hours, and evaluating the common outcomes to the impact of pure glucose, which was used to rank the glycemic impact on a scale of 0-100. Meals lower than 55 are thought of low GI, reasonable meals are 56-69 and excessive GI meals are above 70.

Since its growth, the Glycemic Index has turn out to be a instruments that’s generally used to offer steering for folks with diabetes. It’s additionally used as a part of weight reduction diets, or as a weight reduction eating regimen in of itself. Whereas the Glycemic Index may appear to make sense at first look – we do know that totally different meals can have roughly of an impact on blood sugar – there’s a TON of issues each with how the Glycemic Index was developed, and the way it’s utilized. So let’s debunk the Glycemic Index!

Debunking the Glycemic Index

The Glycemic Index relies on a defective examine design.

The put it bluntly, the examine design behind the Glycemic Index was a scorching mess. For starters, there was a particularly small pattern dimension, with every meals examined on solely 5-10 topics. As a result of there may be fairly a little bit of variability in glycemic impact amongst people, it’s straightforward for the GI of a meals to be thrown off by somebody who’s both extraordinarily reactive or non-reactive to a meals.

One other drawback with the examine was that with the intention to separate the impact of the particular meals versus the amount of carbohydrate consumed, members ate 50 grams price of carbohydrate for every meals. On the floor, this may sound like robust examine design, however this meant that members have been consuming portions of sure meals that have been fairly totally different from how one may eat it in actual life, particularly for greens. For instance, 50 grams of carbohydrate from greens means 10 uncooked carrots, over 25 cups of cucumber slices, and 10 cups of steamed cauliflower. This can be why greens surprisingly had a number of the of the best glycemic results.

Not solely that, however to develop the glycemic index, meals have been consumed alone versus together with different meals. Most individuals aren’t sitting all the way down to a meal of plain boiled potatoes, a cup of canned black beans or dry cereal. We eat meals as a part of meals and snacks, together with different meals that comprise fats, protein, and fiber, which assist decrease the glycemic response. Conversely, different meals that have been examined, like ice cream, yogurt, or potato chips, are sometimes consumed on their very own as a snack or dessert. These are meals that already comprise some quantity of fats and/or protein, which helps decrease the glycemic response. It’s to not say these meals are “unhealthy” or “good,” solely that evaluating them on their very own doesn’t essentially give us a superb image of the actual world affect on blood sugar.

The glycemic affect of a meals depends on many alternative elements.

A potato is a potato, proper? Not relating to glycemic index. Is the potato waxy or starchy? Has it been boiled, steamed, roasted, microwaved or fried? Are you consuming the potato freshly cooked, or was it cooked and cooled (like in a potato salad), or was it cooked, cooled and reheated? Was the potato mashed, sliced or left entire? How lengthy did the potato sit on the shelf on the grocery retailer?

Elements like preparation technique, ripeness, and processing all affect the glycemic impact of a meals. That’s as a result of these processes can break down or rework the starches, fibers, and sugars current in a meals. For instance, a green-ish, much less ripe banana has a glycemic impact that’s about half as a lot as a completely ripened yellow banana. As a banana ripens, the starches break down into sugars, therefore the sweeter taste of a ripe banana. One other instance of how the glycemic index could be altered occurs when starchy meals are cooked and cooled, for instance boiled noodles which have been refrigerated to make pasta salad. Cooling the noodles transforms a number of the starches to resistant starch, which doesn’t break down into sugar throughout digestion, reducing the glycemic impact.

Whereas understanding how these processes affect blood sugar might actually be useful for somebody with tough to handle diabetes, it’s not useful for the common human attempting to feed themselves, particularly when their physique is already doing a fairly arise job of metabolizing sugars. It’s additionally useful in understanding why the Glycemic Index is a particularly imperfect software. After I consider all of the various factors that may affect the GI of a meals, I can’t assist however suppose how overwhelming it could be to maintain all this data in thoughts and make a easy resolution about what to eat for dinner!

The Glycemic Index ignores particular person variability in how meals affect blood sugar ranges.

Even within the unique GI examine, there was fairly a little bit of variability amongst members in how particular person meals impacted their blood sugar. Since then, extra analysis has proven that totally different people could also be roughly delicate to totally different meals. I typically reference an enchanting examine what was achieved in 2016, trying on the glycemic impact of white bread throughout a bunch of 63 people. They discovered that whereas the common GI for white bread was 62 (inserting it within the medium GI class), it might vary by 15 factors both means throughout people. That meant that for some people, white bread was a low GI meals and in others it was a excessive GI meals. Even throughout the similar particular person, the glycemic impact diverse by as much as 60 factors between trials! This examine is a implausible reminder of how individualized diet could be, but in addition a reminder that different elements outdoors of meals can affect blood sugar ranges, like stress ranges, lack of sleep, or hydration.

What Can I Do to Handle Blood Sugar?

So what to do in case you are involved about your blood sugar? Whereas the Glycemic Index is probably not a really useful software, there are different issues you may give attention to which might be fortunately a lot much less traumatic than memorizing the GI of 1000’s of meals! Right here’s a couple of of the issues we work on with purchasers who’ve diabetes, PCOS, or different situations that affect blood sugar ranges:

  • Eat common meals and snacks all through the day. Going lengthy intervals of time with out consuming then consuming a bigger meal can result in huge fluctuations in blood sugar, whereas consuming frequently helps hold it regular.

  • Pair carbohydrate meals with different meals that comprise fats and protein. Purpose to incorporate the gang at your meals!

  • Deal with excessive fiber carbohydrate sources. Whilst you can see from this submit that there’s not a ton of consistency in how meals affect blood sugar ranges, we do know that as a common rule of thumb, carbohydrate meals which might be greater in fiber are typically higher for blood sugar. Examples embrace entire grains, like brown rice, entire grain pasta, and and entire grain bread, starchy greens, like potatoes, sweetpotatoes, and winter squash, and fruit.

Once we work with purchasers on managing blood sugar ranges, we take an individualized method. Nobody-size-fits-all recommendation right here! We additionally attempt to take the stress out of consuming by simplifying diet steering, as a result of consuming doesn’t must be difficult. If you happen to’re fascinated by getting assist with meals, learn extra about our observe philosophy and attain out should you’d like extra details about providers.


  • Wikipedia

  • Upkeep Part: The Hassle with Sugar

  • Jenkins, D. J., Wolever, T. M., Taylor, R. H., Barker, H., Fielden, H., Baldwin, J. M., Bowling, A. C., Newman, H. C., Jenkins, A. L., & Goff, D. V. (1981). Glycemic index of meals: a physiological foundation for carbohydrate alternate. The American journal of scientific diet, 34(3), 362–366.

  • Matthan, N.R., Ausman, L.M, Meng, H., Tighiouart, H., and Lichtenstein, A.H., “Estimating the reliability of glycemic index values and potential sources of methodological and organic variability.” American Journal of Scientific Diet, 2016. doi:10.3945/ajcn.116.137208

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