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Debunking the Glycemic Index — Registered Dietitian Columbia SC


Final week I listened to a current episode of Upkeep Section podcast the place they debunked frequent sugar myths, and it jogged my memory that I’ve been that means to do a weblog publish of my very own debunking the glycemic index. As a diet scholar in a really conventional dietetics program, there was loads 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 once I was at school we realized was completely bunk. Glycemic index is a type of subjects! Though it’s one thing that makes intuitive sense, per standard, diet and our particular person biology is rather more complicated than some chart of what to eat and what to keep away from.

What’s the Glycemic Index?

The Glycemic Index (GI) was a instrument that was initially created within the Eighties by a researcher named David Jenkins to supply 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 value of carbohydrates from particular meals, measuring their blood sugar over the subsequent two hours, and evaluating the typical 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-about low GI, reasonable meals are 56-69 and excessive GI meals are above 70.

Since its growth, the Glycemic Index has grow to be a instruments that’s generally used to supply steering for folks with diabetes. It’s additionally used as a part of weight reduction diets, or as a weight reduction weight loss program in of itself. Whereas the Glycemic Index might sound 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 is predicated on a defective examine design.

The put it bluntly, the examine design behind the Glycemic Index was a sizzling mess. For starters, there was an especially small pattern dimension, with every meals examined on solely 5-10 topics. As a result of there’s 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, individuals ate 50 grams value of carbohydrate for every meals. On the floor, this would possibly sound like robust examine design, however this meant that individuals had been consuming portions of sure meals that had been fairly totally different from how one would possibly 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 among the of the very best glycemic results.

Not solely that, however to develop the glycemic index, meals had been consumed alone versus together with different meals. Most individuals aren’t sitting right 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 include fats, protein, and fiber, which assist decrease the glycemic response. Conversely, different meals that had 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 include 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 an excellent image of the true world influence on blood sugar.

The glycemic influence of a meals relies on many various 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 complete? How lengthy did the potato sit on the shelf on the grocery retailer?

Components like preparation methodology, ripeness, and processing all influence 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 might 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 among the starches to resistant starch, which doesn’t break down into sugar throughout digestion, decreasing the glycemic impact.

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

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

Even within the unique GI examine, there was fairly a little bit of variability amongst individuals in how particular person meals impacted their blood sugar. Since then, further analysis has proven that totally different people could also be roughly delicate to totally different meals. I usually reference an enchanting examine what was accomplished in 2016, trying on the glycemic impact of white bread throughout a bunch of 63 people. They discovered that whereas the typical GI for white bread was 62 (putting it within the medium GI class), it might vary by 15 factors both approach 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 inside the identical particular person, the glycemic impact different by as much as 60 factors between trials! This examine is a improbable reminder of how individualized diet might be, but additionally a reminder that different elements exterior of meals can influence blood sugar ranges, like stress ranges, lack of sleep, or hydration.

What Can I Do to Handle Blood Sugar?

So what to do if you’re involved about your blood sugar? Whereas the Glycemic Index will not be a really useful instrument, there are different issues you may give attention to which might be fortunately a lot much less nerve-racking than memorizing the GI of 1000’s of meals! Right here’s a number of of the issues we work on with shoppers who’ve diabetes, PCOS, or different circumstances that influence 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 massive fluctuations in blood sugar, whereas consuming recurrently helps hold it regular.

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

  • Concentrate on excessive fiber carbohydrate sources. When you can see from this publish that there’s not a ton of consistency in how meals influence blood sugar ranges, we do know that as a basic rule of thumb, carbohydrate meals which might be increased in fiber are usually higher for blood sugar. Examples embrace complete grains, like brown rice, complete grain pasta, and and complete grain bread, starchy greens, like potatoes, sweetpotatoes, and winter squash, and fruit.

Once we work with shoppers 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 need to be sophisticated. In the event you’re concerned about getting help with meals, learn extra about our observe philosophy and attain out should you’d like extra details about providers.


  • Wikipedia

  • Upkeep Section: The Bother 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 change. 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 Vitamin, 2016. doi:10.3945/ajcn.116.137208




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