Carbohydrates are classified into two types based on how fast or slow it digested; they are simple and complex carbohydrates.
Glycemic Index, Load & Response
Glycemic index (GI), glycemic load (GL), and glycemic response (GR) are the three critical characteristics of the carbohydrate food on your blood glucose level. Once you are well-versed with these terms, then you can smartly choose only good carbs and learn to avoid bad carbs.
Glycemic Index (GI)
What is glycemic index GI?
Glycemic index (GI) is a number, which tells you how fast that carb affects your blood glucose level. All carbohydrates are digested and broken down into glucose in varying rate (slow to fast), which are indicated by the “Glycemic Index or GI.”
Complex carbohydrates are digests slowly, and release glucose is steadily in the bloodstream. On the other hand, digestion of the simple carbohydrates are quick, and glucose is dumped into the bloodstream and makes a blood-glucose level spike.
Food close to nature tends to have a low glycemic index than refined and processed foods having a high glycemic index.
Classification of Glycemic Index
Glycemic index is of three levels, they are:
- Low GI (good) carbs: 55 or less
- Moderate GI (neutral): 56 to 60
- High GI (bad): 70 or more
Digestion of low GI (55 or less) carbs and release of glucose into the bloodstream is slower. Also, the blood glucose rise of low GI carbs are much lower when compare to the moderate GI (56 to 60), and high GI (70 or more).
High GI (70 or more) carbs such as refined sugars and bread are digested easily and release of glucose into the bloodstream more quickly and the blood glucose spikes much faster than low GI foods such as vegetables and whole grains.
How glycemic index affect your blood sugar level?
Eating a lot of bad carbohydrates (high GI) will have a hard time controlling your blood sugar.
Glycemic index food list
- Low GI Foods - whole wheat, oatmeal, oat bran, pasta, converted rice, barley, bulgar, Sweet potato, corn, yam, lima/butter beans, peas, legumes and lentils, Most fruits, non-starchy vegetables, and carrots.
- Medium GI foods - are rye and pita bread, Quick oats, Brown, wild or basmati rice.
- High GI foods - White bread, Cornflakes, puffed rice, bran flakes, instant oatmeal, white rice, rice pasta, macaroni, and cheese from the mix, potato, pumpkin, Pretzels, rice cakes, popcorn, saltine crackers, melons, and pineapple.
How do you modify the glycemic index of a meal?
I like a few high GI foods. Is there any way to change the Glycemic Index?
Yes, it is possible to lower the glycemic index of high GI foods by combining it to fat, fiber, and acids such as lemon juice or vinegar. Also, the glycemic index of the fruits such as bananas is low while about to ripe and goes high after-ripen.
Seven factors can modify the actual glycemic index of a meal!
- Cooking – Heat, water used, and length of cooking food can modify the GI of the food. During cooking starch in the food gelatinized, making it easier to digest and change into high GI. After cooling, the gelatinized starch reorganize its original state and thus back to its low GI number. For example, GI of raw carrots is 20, and the once boiled, its GI raises to 50.
- Protein – Combining protein with carb slow down the digestion of starch, thus lowered the GI.
- Processing – Finally ground or milled starchy food that reduces in the particle size makes it easily digestible and modified into high GI.
- Fiber – Addition of fiber into a food can lower the GI of the food, because fiber thickens (soluble fiber) or indigestible thus slow down the digestion of starch.
- Fat – Addition of fat increase the GI of the food by slowing down the digestion. For example, the GI of potato chips is 57 due to the presence of oil (fat), and GI of a baked potato is 85.
- Acid – Presence of acid in the food slows down stomach emptying and thus the GI. Adding vinegar or lemon juice lower the GI. Also, sourdough bread has a much lower glycemic index value than regular bread. Research shows adding vinegar to a meal can reduce the post-meal blood sugar rise by about 50%.
- Ripeness – Unripen bananas have low GI about 40, but after-ripen it has a high GI of about 65. Also cooked unripe banana raises it’s GI to about 65.
Glycemic Index & Diabetes Control
Persons with diabetes who want to use the GI for the betterment of their blood glucose control should eat a healthy, low GI diet. Some tips include:
- Increase the consumption of low GI food such as whole grains, nuts, legumes, fruit, and non-starchy vegetables.
- Decrease the consumption of starchy high GI foods such as potatoes, white rice, and white bread.
- Eliminate (but rarely you can enjoy within limit) the consumption of sugary foods like cookies, cakes, candy, and soft drinks.
What is the best time to bolus insulin to match the glycemic food you ingest?
If you are eating a meal with mainly high glycemic index (70 or more) foods, then it digests faster, causes massive blood sugar peaks within minutes. So best to bolus your insulin 15 to 20 minutes before eating.
Eating a meal with mainly moderate glycemic index (56 to 60) foods then digests a bit slower, causes modest pronounced blood glucose peak in about 45 to 70 minutes. And the best time to bolus your insulin is 5 to 10 minutes before eating.
Eating a meal with mainly low glycemic index (55 or less) foods then digests much slower, causes less pronounced blood glucose peak in about an hour or two. And the best to bolus is right after eating.
The above said insulin bolus timing might help to coincide closely with the blood glucose peak after eating. However, you need to test and fine-tune the timing for perfect individualization.
Glycemic Load (GL)
What is glycemic load?
The glycemic response to the food depends not only on the glycemic index but also on the total amount of carbohydrates, and this led to the concept of glycemic load. Glycemic load accounts for the amount of carbohydrate in the food and how this each gram of carb raises the blood glucose levels.
GL is the measure of the overall effect of the food on your blood glucose level. The GL is the more accurate indicator because it incorporates both the quality and quantity of the carbs consumed.
GL = GI x carbohydrate (in grams)/100
Calculate the glycemic load by multiplying the number of carbs in grams per serving by the food’s glycemic index divided by 100. Where available carbohydrate = total carbohydrate - dietary fiber. One unit of GL approximates the glycemic effect of 1 g of glucose.
GI, GL & prevalence of diseases!
Traditionally our ancestors consumed nature unprocessed plant-based diets high in fiber such as whole grains, legumes, and nuts as staples. These diets were low GI and low GL. Shifting from traditional natural food to western artificial (highly processed) foods raised the prevalence of diabetes, obesity, and CVD.
Researchers in the American Journal of Clinical Nutrition found that eating foods with high glycemic loads could be linked to chronic diseases. Some such conditions are type 2 diabetes and heart disease; it may be due to the raising of blood sugar and insulin levels.
The intake of a reduced GI/GL diet favors the glycemic control of the studied population. Reference: Nutricion Hospitalaria. 2012; 27(2):510-515.
Low GI & GL is associated with lower glucose and insulin level. Lower glucose and insulin levels are associated with improved risk profile;
- increased high-density lipoprotein cholesterol,
- low levels of glycosylated proteins (hbA1C),
- oxidative status,
- hemostatic variables, and
- endothelial function.
Classification of glycemic load
The glycemic load is of three levels, they are:
- Low GL: less than 10,
- Intermediate GL: 11 to 19
- High GL: more than 20.
Glycemic Response (GR)
Glycemic response of a food’s (carb) is the effect it has on blood sugar levels after consumption. It is natural to have a rise in blood glucose and insulin levels after eating and then back to the normal after a short period.
Glycemic index is conceptually the glycemic response produced by a portion of food that contains 50 g (or 25 g in some case) of the carb. GR is in percentage.
GI, GL & GR are all used to stabilize glycemia
Many dietary ideas to reduce postprandial glycemia that includes:
- Low carb – minimize the amount of carb consumption.
- Include fat, protein, fiber & acid – increase these to slow down gastric emptying.
- Incorporate amino acids (protein) – adding amino acids help increase the secretion or effectiveness of insulin.
- Low GI – replace high GI food with low GI foods.
The fundamental flaw with low GI foods
The general belief is that GI of 55 or lower is good for the health. However, the sweet poison fructose (specifically fructose corn syrup) has the GI of 19. If you add fructose to a high glycemic food, then it becomes low or moderate GI food. Because adding fructose is the recipe to lower GI.
Fructose is super-low GI; then it must be “good" right? Not! It is known for its atherogenic and insulin resistance triggering character. Super low-GI fructose is a major cause of global obesity, diabetes, and other diseases.
A low GI food may comparable to the tortoise, and the high GI food may be equivalent to the hare. Hare (high GI) may be fast blood sugar rise, and tortoise might be slower blood sugar rise, but both will reach the destination (BS raise).
What is your take-home extract about the glycemic index? Eat natural unprocessed foods.
Some studies show that people who eat a low GI diet tend to be healthier; maybe these people tend to eat fewer processed foods.
GI number says nothing about the healthiness of food. But GI advocate, as well as skeptics both accept in common, is fresh, natural, whole products.
A glycemic index is a number indicating how quickly a food raises the blood glucose level. While all carbohydrates except fiber are converted into glucose eventually, just some carbs do much faster than others.
Your focus should be on eating natural, whole, unprocessed foods and not require to worry about what is a glycemic index that it.