My publisher desires a glycemic index (GI) chart for our upcoming book on smart glucose monitoring. I’m checking out GI and its sister, glycemic load (GL), but numerous things can alter GI and GL. How do you use these tools?
As Jacquie Craig, MS, RD, LD, CDE explained in a post on this site,
GI ranks carbohydrates from 0 — 100, based on how much and how fast they affect blood glucose levels. A greater number indicates the food has a bigger impact on blood glucose levels. Glucose itself has a ranking of 100.
GI is necessary for people with Type 2 diabetes, because they typically have actually a delayed insulin reaction. If glucose increases quickly, the body does not react quickly enough, and glucose levels can get way too expensive after meals. So we want low-GI foods.
GI doesn’t inform you how much glucose will eventually get into your system, just how much of a blood sugar increase the food produces. To enhance the GI, Dr. Walter Willett at Harvard helped establish the idea of glycemic load (GL). GL combines the GI with a procedure of how much carbohydrate there remains in a food.
So in theory, GL can inform you a provided food’s total influence on your blood glucose levels, which ought to assist in meal planning, insulin dosing, and food options. But the reality of GI and GL is a lot more complicated.
Also read: How Many Carbohydrates Should I Have?
How Are GI and GL Determined?
You can’t tell the GI or GL of a food by examining it in a lab. That’s because various individuals’s gastrointestinal systems handle various carbs in a different way. We also take in and break down the exact same carbohydrates into glucose in a different way at different times, depending on what other nutrients are being taken in.
For example, a plain pizza with tomato sauce and Parmesan cheese has extremely high GI, around 80. However a super-deluxe pizza with all the fixings has a low GI of 36. The GI is lower due to the fact that the protein and fats in the toppings decrease the absorption of carbs and slows their developing into glucose.
Since you can’t tell GI or GL in a test tube, glycemic index values are figured out by feeding 8 to 10 people a set portion of the food (after an over night fast). Then samples of their blood are taken every 15 — 30 minutes and their glucose levels are determined. The GI values that the foods register in the participants are balanced to offer a GI number.
The GL is determined from the GI using the formula GL = (GI × Net Carbs) ÷ 100. (Net carbohydrates amount to the overall carbohydrates minus dietary fiber.)
So if a plain pizza has a GI of 80, and 27 grams (about one ounce) of net carbs in 100 grams, its GL would be 80 increased by 27, divided by 100, for a total of 22. For GL, 20 and over is considered high, and 10 or below is thought about low. Levels in the variety of 11 — 19 are considered medium.
For GI, anything below 55 is low, and anything over 70 is considered high. Numbers from 55 — 69 are medium.
The same foods can have an extremely different GI and GL depending on how they are prepared. A boiled sweet potato has a low GI of 44 and a medium GL of 11. But if baked for 45 minutes, the same sweet potato has a GI of 94 and a GL of 42, both extremely high. Baking has actually essentially turned the sweet potato into candy.
White potatoes likewise have a greater GI and GL when baked. Microwaving frequently raises GI and GL. Have you ever discovered how sweet beets taste after baking or microwaving? That’s because much of their carbohydrate material has actually been transformed into glucose.
Even the exact same cooking approach can give various results. Spaghetti cooked al dente (boiled for 8 minutes) has a much lower GI and GL than soft (boiled for 20 minutes) spaghetti.
Different brands or varieties of the exact same food can have extremely different GI and GLs. Teacher Jennie Brand-Miller of the University of Sydney, Australia, has actually developed a list of thousands of foods based upon her tests and the released results of others. Her list includes two types of rice milk, one with a GI of 92, another of 79. Sweet corn from New Zealand has a GI of approximately 37, while South African sweet corn gets about a 62.
This is truly a wonderful, if complicated, list, and it can be seen at Mendosa.com and an updated list is readily available at GlycemicIndex.com.
Also read: Carb Counting for People with Diabetes
Different People, Different GI/GL
Even if you could find the published GI or GL of a particular food, you could not ensure that food’s effect on your individual glucose numbers. People vary substantially in their reaction to foods. And in real life, foods are seldom consumed one at a time. We have beverages and other foods with them, which can affect their glucose reaction in the body.
It seems the only way to be sure about a specific food’s impact on you is to inspect your glucose after consuming it. Ideally check in the past, too, so you can tape-record how much change there has actually been.
Do you take a look at GI and GL numbers or consider them in meal planning or insulin dosing? What info sources do you use, and how do you use that info? Thanks in advance for any assistance you can provide.