Dr. Dennis Van Hoof, PhD, CLC
“Not all carbs are made equal.”
Glycemic Index and Glycemic Load
Glycemic Index (GI) — Sugars and other carbs (which is short for “carbohydrates”) come in simple forms and complex forms (see Blog post “The bitter-sweet truth“). Glucose is a simple form that quickly enters your blood after a meal; starch is a complex form that takes longer to digest (which means breaking it down into simple sugars for absorption into the blood). The speed with which the type of sugar enters your blood stream is indicated with a Glycemic Index (GI) number or value, and differs for each type of food; the higher the number, the faster the sugar is absorbed. The value of glucose is set to 100 as a reference.
Combining sugary/carb-rich foods with protein and fat will slow down the sugar absorption speed. Many whole foods and well-balanced meals (see Blog post “The balancing act of diabetes“) consist of a mixture of carbs, protein and fat in different ratios. So even when there are some high GI nutrients in there, the food as a whole does not spike your blood glucose.
There are tons of data sheets and tables on the internet with GI values for different kinds of foods and drinks. Search for your favorites!
Time your high and low GI foods wisely.
Glycemic Load (GL) — Knowing how fast the different types of carbs enter your blood stream is only part of managing your blood glucose (see Blog post “Timing for excellent diabetes management“). The other part is how much the carbs will increase your blood glucose level. This is indicated with the Glycemic Load (GL). While a small sugar candy will raise your blood glucose very quickly (high GI), the total amount of sugar is probably not be enough to increase your blood glucose all that much (low GL).
Assuming you have 5 liters of blood in your whole body, 1 gram of sugar equals 20 mg/dL. A blood glucose value of 80 mg/dL then means that there is about 4 grams of total glucose circulating in your blood stream (see Blog post “Blood glucose“). So in theory, a candy containing just 1 gram sugar should raise that no higher than 80+20=100 mg/dL. But of course biology is not like mathematics, and how much your blood glucose will actually rise depends on many factors; for instance how big you are, if you are physically active, and how much insulin is in your blood.
To find out what typical foods in certain quantities do to your blood glucose level, you can measure the weight of every portion before you eat it, and then monitor what happens to your blood glucose. After a while, you will get the hang of it and be able to estimate how much your blood glucose will go up just by looking at the food on your plate. This will be very helpful in making the right choices; especially when you are eating out.
Make smart choices with high and low GL foods throughout the day.
You may wonder if all high GI/GL foods are bad for diabetics. The answer is no. But you have to be selective about what type of foods you eat at certain moments of the day. As explained in the Blog post “Timing for excellent diabetes management,” it all depends on what you need and how much. For instance, if you are going to do a high-intensity workout, it is totally fine to eat some high GI food right before you start. When you start exercising, your muscles will first use their glycogen stores and circulating blood glucose to fuel the flexing. The high GI food that you just ate will maintain your blood glucose at high enough levels, so that you can keep up the activity. However, when you do endurance sports (like a long hike or bike ride) you will need to consume higher GL and preferably low(er) GI foods to keep you fueled for several hours.
Another situation where high GI foods are recommended is when your blood glucose is dangerously low (see Blog post “Blood glucose“). High GI foods (or drinks) will quickly get you back in the safe zone. But be careful to not over-consume, or you will end up with a too high blood glucose level.
For the rest of the day, and especially for your dinner, it is best to choose low GI/GL foods for your meals to prevent spiking your blood glucose. Use the 50%/25%/25% rule to balance your meal: half your plate filled with veggies, a quarter with low GI/GL carbs, and a quarter with lean protein (see Blog post “The balancing act of diabetes” for examples).
Keep an eye out for my next blog, and I hope to see you soon to get you started on the journey to your new life!
Dr. Dennis Van Hoof is a Certified Life Coach (CLC) with an academic PhD degree in Biochemical Physiology. By combining 20 years of first-hand personal diabetes experience with his in-depth scientific background, he developed a method to efficiently manage his own diabetes in a sustainable way. To learn how you can do this too, reach out for personal Diabetic Lifestyle Coaching or follow a group workshop that is specifically tailored to people with Type 1 or 2 Diabetes as well as pre-Diabetics and those at risk due to being overweight or obese. His clients thrive with their challenges and become an inspiration™ to others — with or without diabetes.