The Glycemic Index, Explained

Tonnes of diets out there recommend eating low GI foods, but what exactly is the glycemic index? Subscribe to Nourishable at / nourishable
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References
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The glycemic index, or GI, is a method used to rank foods based on how they impact your blood glucose. It was originally created to help people with diabetes select foods to improve their glycemic control by ranking foods as low, medium, or high GI. You can’t just guess the GI of a food by looking at a food label, it has to be tested. To express the impact of a particular food, we need a reference to compare it to. 50g of pure sucrose requires little digestion so the glucose can be rapidly absorbed into the bloodstream. I’ve fasted for over 12 hours and I haven’t had any physical activity this morning, so I can drink my pure sugar drink. I’m using a continuous glucose monitor to measure my blood glucose every 5 minutes. And now I’m going to sit tight for 2 hours so we can see the impact on my blood glucose. So its the next day and now we can do an experiment to determine the glycemic index of a particular test food. I’m going to test this Dave’s Killer Bread the 21 whole grains and seeds version. We want to compare like to like. Today I’m going to eat a serving of bread that also gives me 50 grams of digestible carbohydrate. And that word digestible is actually pretty important, because of fiber, which is also a carbohydrate but we can’t actually digest it. We have to actually subtract the fiber from the total carbohydrates in the product. When I look at the nutrition facts panel, what I see is that one slice of bread has 22 grams of carbohydrates in it, but 5 of those grams are fiber. If I want to get 50 grams total then I need to eat almost three whole slices of bread. Okay, so here I have 50 grams of digestible carbohydrate of Dave’s Killer Seed bread. In this graph we see my blood glucose to the sugar drink in red and to the bread in blue. It’s pretty striking how different they are over these two hours! The bread caused a much more gradual rise in blood glucose, and the peak was substantially lower compared to the sugar drink. Now to actually calculate the glycemic index, we need to calculate the area under the curve for both the sugar drink and the bread separately. Then we divide the bread test food area by the sugar drink reference and multiply by 100 to express it as a percent. Using this method, the glycemic index for Dave’s Killer Seed bread is 34, which puts it in the low GI category. From this n of one experiment, we observed that Dave’s Killer Seed bread raises my blood glucose only 34% as much as the sugar drink over a two hour period. I was actually pretty surprised at how low the GI for this bread was. I definitely expected it to be lower than the sugar drink due to the fiber content, since fiber slows down the absorption of glucose, but I really didn’t think that it would be categorized as a low GI food because it’s still bread! And the reality is, it might not be! We can’t exactly conclude that the GI of Dave’s Killer Seed Bread is for sure 34 just from this experiment - determining the GI of a food needs to be done in a larger sample of study participants than just me, and each participant needs to do the experiment in duplicate or triplicate, meaning drinking the sugar drink on three separate days and eating the test food on three separate days. Usually that sugar drink is made of pure glucose rather that the sucrose table sugar. It also turns out that there’s a few more complications about the glycemic index and its applicability.

[@Efforlesspassiveincome]

Once upon a time, there was a man named John who loved to eat sugary foods. He enjoyed candy, cakes, and ice cream regularly, but he started to notice that he was feeling more tired and sluggish than usual. He went to see a doctor, who told him that his blood sugar levels were high and that he needed to make some changes to his diet. The doctor introduced John to the concept of the glycemic index, which is a measure of how quickly carbohydrates in food are digested and absorbed and how they affect blood sugar levels. John was surprised to learn that the foods he loved to eat were high on the glycemic index and were causing his blood sugar levels to spike, leading to fatigue and other health issues. The doctor advised John to start incorporating more low glycemic index foods into his diet, such as whole grains, vegetables, and fruits. John took the advice to heart and started making changes to his eating habits. He swapped out sugary snacks for healthier options and started cooking meals with more low GI foods. Over time, John noticed that he had more energy and felt better overall. His blood sugar levels were also more stable, and he was able to maintain a healthy weight. John was grateful to have learned about the glycemic index and how it had helped him take control of his health.

[@balakumarseenivasan3502]

Clear explanation. Thanks a lot😊

[@dr_bodling]

Was always curious how the GI was calculated. 🤓 great explanation! thanks!

[@green08green08green]

This was really in depth and fun to watch. Looking forward to see more videos like it!

[@kintquintana6551]

This video is just perfect, you are amazing at explaining nutrition topics! 100% informative, interesting and original 😍

[@shrutiwaghmare5215]

Thank you for the video ❤

[@roundysquares]

Wow! This is absolutely fantastic content. Great job!

[@KanishkMittal-o1d]

Great video, very simple to understand! Thanks!

[@jayparkkc5640]

That was very informative, thanks!

[@omskariyazmaraikayer913]

This is really the first time I understood GI from the correct perspective. I hope there is another video for GL from you.

[@HARSHFF280]

Thank you so much mam🎉

[@Healthiswealthofficial14]

Please explain me in details if possible with examples how to calculate GI

[@SandeepKumar-fw5hy]

Explained so simply … thank you .

[@user-ds7ld4ph8v]

Thank you!!!please, explain the GL formula and how it impacts the GI formula. Thanks again

[@skandhansai9079]

It's like dawn good explanation, I loved it aa lot thanx mam

[@cincodemanny]

Awesome information!

[@saranya.s4635]

Easily understandable explanation

[@shadreckkalenga874]

Perfect explaination ❤

[@alotan2acs]

Do fiber supplements help reduce blood glucose spikes?

[@k.t.1594]

Amazing video!

[@training7574]

Very informative and funny, thanks!

[@tracycabrera1950]

Very informative video

[@Michaelmaggimee]

Thank you

[@coachbbbadbrenda8326]

Thank you so much. 😊

[@deaglefly4338]

Big hack for you guys! Cook rice and then let it cool in the fridge for several hours and heat it back up in microwave and glycemic levels drop and steady significantly!

[@palviika8712]

Right! Because of the presence of retrograded amylose which occurs after the cooling of moist food. As Retrograded amylose is RS3 thus its degradation would occur extremely slow. Slow degradation causes slow inclusion of Glucose into blood and hence Low GI🌸

[@brainsnbrawn]

​@@palviika8712wow! How did you know this? I'm so amazed😮

[@bradardell1507]

As an asian this gets under my skin

[@DRadioactive]

Bravo dear!

[@Puhazhenthi]

Very useful

[@samyswry7497]

you are great thank you

[@artculturemusic]

Thank you:)

[@nahiankhondokar1046]

Wonderful vedio

[@andrew_trucker]

😂😂😂thats my glucemic index finger 😅😅😅

[@dheerajvats4273]

Wow , i hope there were more people who explain things this pin pointed. I now have a metric to compare things for insulin spikes :) . So insulin stops fat burning process . Can you also explain how much time in hours can we expect fat burn to stop if i eat sugar vs jaggery vs carbohydrates (potato vs bread etc). This would really give intuition on frequency to supress sugar cravings and estimate loss in fat burning if you are on a leaning schedule. Like for example i can eat sugar at the time i am consuming carbs as anyway fat burning will stop due to insulin spike due to carbs. If i would have eaten first carbs and then after 2 hours again sugar , i loose 4 hours of fat burning. If i would have taken sugar with carbs i would have saved 2 hours of fat burning in body. Am i right. If possible please explain.

[@tracycabrera1950]

So should we cut out all carbs and sugars if we have postprandial hypoglycemia

[@BigBoss-mf7ff]

So, the GI index of any food is calculated on 50 Grams uptake all the time? Thanks

[@ainamaisarah4414]

Why is must be 50g glucose?

[@yennyjen5742]

I see the spike of almost 200. Are you diabetic? The dr just told me I am pre diabetic and I have a countinous glucose monitor. I been so overwhelmed finding out i have spikes of sometimes 175-200.. I am prediabetic. If you don’t have diabetes.. does that mean even normal people spike?

[@kracknats1]

what really is the formula for GI? Also, the formula in calculating the GL. Thank you.

[@datrucksdavea2080]

did U fast for 12hrs. before the Dave's bread? I think that would make a difference. Anyway that was crazy and abnormal drinking the sugar water on an empty stomach, ty take one for the team..... Cool TY

[@bon7048]

Where did you get the number 50 from?

[@Rony-kb5jv]

I think graph has been misinterpreted. The red and blue, both area under the curves should extend up to x axis.

[@bencyber8595]

low or high G I

[@MaybejustNarbe]

This is interesting... but does a diabetics body respond the exact same way to the sugar and bread as a normal persons? I'm a T1D and 3 slices of bread would send me through the roof, not as high as the pure sugar, but they would both be +200. Its an interesting concept for a healthy person, but a diabetics body doesnt respond the same way to sugars in general as a normal person does :( I wish I could eat fruit, but it still sends me +200 :(

[@MartinUToob]

Can you do a watermelon? 🍉

[@AzherZarach-l9o]

Allen Anthony Thomas Matthew Wilson Patricia

[@NightNurseMike]

Can you compare eating an orange to drinking orange juice equivalent

[@Nourishable]

I have a video in the works about that! Stay tuned :)

[@mohamedsilem2803]

@@Nourishable where I can't find the video??

[@dianasolfest7237]

​@@mohamedsilem2803 man, really!!

[@mohamedsilem2803]

@@dianasolfest7237 ?????????

[@Spoons4Hands]

and now the question is what does that mean? Because there is still sugar in the bread right? Exactly the right amount actually. Where does that go? It seems like the bread would have a different effect on e.g. calorie intake from the two different foods?

[@philthejet]

Interesting video. The voice fry is annoying if I may say so.

[@RobertWalker-ib4ei]

GI means nothing, I love these stupid phd’d misleading public, GL - Glycemic Load matters. I hope this great doctor will be happy to make another video to put it right!

[@gabrielamunozova798]

Great video!!!