When you hear the letters “GI,” you might think of gastroenterology. But the GI has another meaning in the world of health and wellness: the glycemic index.
So what is the glycemic index, and should you consider it when deciding what foods to eat? Read on for an explanation of GI scores and the factors that can affect them, as well as lists of high and low glycemic index foods.
What is the glycemic index?
THE glycemic index measures how quickly after consumption a food causes insulin and blood sugar levels to rise (glycemic response). Glucose is the main sugar found in the blood – hence its synonym blood sugar – and is our main source of energy. The glycemic index ranks foods on a scale of 0 to 100, with pure glucose being its benchmark at 100.
For people with diabetes (a condition in which blood sugar levels are already too high), GI rankings are an essential tool to help control blood sugar. But those without diabetes may also choose to pay attention to GI scores. For what? Sticking to a mostly low-GI diet can help you feel fuller, faster, and eat fewer calories overall, because low-GI foods generally take longer to digest and don’t cause stomach upset. sugar spikes.
This is important because sugar spikes are most often followed by steep drops, which eventually trigger hunger. So, foods that score high on the glycemic index can start you on a spin cycle of increased cravings and, ultimately, increased calorie intake.
While focusing on GI scores alone isn’t an all-encompassing approach to a healthy, balanced lifestyle (more on that in a moment), the glycemic index can help you weed out processed junk food, which leads to promising health outcomes.
What do glycemic index scores mean?
Our body digests and absorbs high GI foods quickly, while low GI foods are digested and absorbed at a slower rate. High GI foods often contain processed carbs and sugars, and low-GI foods are usually high in fiber, protein, and/or fat. Foods that contain no carbs at all (like plain chicken) don’t get a GI value.
Here’s another way to look at GI scores: A food with a GI of 47 raises blood sugar by 47% as much as pure glucose.
Foods belong to one of the following categories three ranges:
- Weak – GI of 55 or less. This includes most fruits and vegetables, beans, minimally processed grains, pastas, nuts, and low-fat dairy products.
- Medium/Moderate – 56 to 69. Pineapples, grapes, potatoes, couscous and honey fall within this range.
- High – 70 or more. White bread, watermelon, white rice, baked goods, most crackers and packaged breakfast cereals.
To note: It’s not certain that low-GI foods will always be healthier or more nutrient-dense than high-GI ones. “A chocolate bar and a cup of brown rice both have a GI of 55, but rice will provide better nutrition,” says the spokesperson for the Academy of Nutrition and Dietetics. Sonya AngeloneMS, RDN, CLT.
Glycemic Index Vs. Glycemic Load
Glycemic index scores represent the effect on blood sugar of 50 grams of carbs from a given food minus fiber (i.e. net carbs). But they don’t take into account how much of that given food it takes for a total of 50 grams of carbs.
Like the Academy of Nutrition and Dietetics Remarks, the GI score of beetroot (64) is 11 points higher than that of rice (53). But to consume 50 grams of beet carbs, you would need to eat nearly four cups of it versus just one cup of rice.
This is why the measurement of the glycemic load was introduced. It’s kind of like the difference between weight and BMI, and offers a more realistic idea of a food’s effect on blood sugar based on likely serving sizes.
Factors that can modify the glycemic index of a food
GI scores can fluctuate depending on a number of variables.
1. Preparation
How you cook (or don’t cook) a food can have a significant impact on its effect on blood sugar. High fiber foods, for example, tend to have a lower GI. But cooking can break down fiber, which means the GI score could increase, Angelone says.
“Cooking helps soften cell walls, hydrate starches, and make things more digestible,” says scared georgia RD, CSSD and author of Lean habits for lifelong weight loss. “Well-cooked pasta, for example, has a higher GI than pasta cooked al dente.” But rather than removing the pasta from the burner before it’s fully cooked, Fear says it’s more helpful to stick to proper portions.
In another example of the effect of food preparation on the glycemic index, a peeled and boiled sava potato for up to half an hour scores 118. On the other hand, this same potato a day later, after refrigeration and cold consumption, records just 88.
2. Combine Foods
Often we don’t eat just one food at a time. And consuming a meal containing a small amount of a high-GI food with protein, fat, and lots of fiber won’t have the same effect on blood sugar as eating any of these foods alone.
One of the most effective ways to regulate GI scores is to combining high GI foods with low GI foods. Acids, fats, proteins and fibers can all reduce the overall GI meal score. For example, an apple with cheese, nuts, or yogurt will have a lower overall GI score than eating that apple alone.
And that impact can extend beyond a single meal. Soluble fiber, for example, has the effect of lowering blood sugar. Consuming fiber-rich, low-GI foods for breakfast can therefore help moderate glycemic response to everything you eat for lunch. In contrast, researchers report that breakfasts lacking in fiber and high in GI foods can negatively impact how you digest food for the next few hours, leading to a potential drop in blood sugar control after lunch.
3. Maturity
The length of time your fruit matures can also affect the GI. “Ripening tends to increase the score since the carbohydrates in a fruit start out as starch and turn into sugar as they ripen,” Angelone explains. A green bananafor example, has a GI of less than one ripe banana.
List of foods with a low glycemic index
Fruits and fruit juices
- Plums: 24
- Blackberries: 25
- Grapefruit: 25
- Prunes: 29
- Raspberries: 32
- Tomato juice: 33
- Apricots: 34
- Apples: 40
- Strawberries: 40
- Pears: 42
- Tangerines: 42
- Apple juice (unsweetened/clear): 44
- Grapefruit juice: 48
- Blueberries: 53
- Peaches: 56
- Appointment: 62
- Cherries (black/raw): 63
- Cranberries (dried): 64
Beans and legumes
- Green beans: 15
- Snowball: 22
- Red beans : 29
- Lenses: 29
- Lima beans: 32
- Black-eyed peas (boiled): 33
- Butter beans: 36
- Chickpeas (boiled): 36
- White beans : 39
- Pinto beans (boiled): 39
Non-starchy vegetables
- Cabbage: ten
- Onions: ten
- Artichokes: <15
- Lawyers: <15
- Cauliflower: <15
- Eggplant: <15
- Mushrooms: <15
- Asparagus: 15
- Broccoli: 15
- Celery: 15
- Cucumber: 15
- Lettuce: 15
- Peppers: 15
- Tomatoes: 15
- Zucchini: 15
- Turnips: 62
- Greens (wild): 68
Cereals
- Barley: 22
- Rye: 29
- Wheat tortilla: 30
- Wheat pasta: 37
- Bulgur: 46
- Wild rice: 57
- Oats (not instant): 59
Nuts, olives and oils
- Almonds: <15
- Peanuts: 13-23 (depending on the region)
- Cashew nut: 25
- Chestnuts: 54
Dairy products, fish, meat, soy and eggs
- Greek yogurt: 11
- Lean red meat: 21
- Almond milk: 25
- Fish: 28
- Skimmed milk: 32
- Egg: 42
- Soy milk: 43
- Low fat cheese: 55
List of high glycemic index foods
Fruit
- Overripe bananas: 48
- Pineapple: 66
- Watermelon: 72
Beverages
- Apple juice: 44
- Orange juice: 41-46 (depending on the region)
- Pineapple juice: 46
- Coca Cola: 63
- Gatorade: 65-89 (depending on flavor)
Vegetables
- Parsnip: 52
- Corn (canned or frozen): 55
- Baked Potato): 85
Cereals
- CEREALS with bran: 42
- White rice: 64
- Whole wheat bread : 71
Snacks
- Jam: 49
- Goo: 52
- Pound cake: 54
- Cookies (oats): 55
- Corn chips: 72
- Donut: 76
- Crackers: 77
- Candies (jelly beans): 80
- Pretzels: 83
Source: Glycemic Index Foundation GI food database.
Tips for Navigating the Glycemic Index
Keep these principles in mind when prioritizing glycemic values for foods.
Eat fewer processed foods
“Look for foods that are less refined and contain intact fiber, such as whole grains, legumes, vegetables. They will have less of an impact on blood sugar,” says Angelone.
In other words, choose foods in their natural state as often as possible. “Whole fruits and vegetables, beans, and whole grains tend to score lower than their juices, or refined grains, sugars, and foods with added sugars,” says Fear.
Combine foods
“Eat carbohydrate-rich foods with fat, fiber, and/or protein, and eat them raw or lightly cooked,” says Angelone. “This will slow down the rate at which carbs are absorbed and metabolized.”
Eat certain low-GI foods in moderation
Not all low GI foods are healthy. The glycemic index is just one indicator of many — including saturated fat, sodium, and fiber content — of a food’s impact on your body.
“High-fat cheese and ice cream, for example, rank quite low because the fat in these foods slows glucose absorption,” says Fear. “That’s not to say that filling a plate with cheese and ice cream is a balanced or healthy meal.”
To move
“There is also evidence that the glycemic impact of a given food is lower after physical activity. A walk before or after meals is always a good idea,” says Fear.
