The glycemic index is a scale that relates to how quickly or slowly a given food will cause your blood glucose level to rise. Foods low on the glycemic index (GI) scale tend to cause a slow, steady rise in blood sugar. Meanwhile, foods high on the glycemic index cause more significant spikes in blood glucose levels.
Low GI foods tend to foster weight loss, while foods high on the GI scale may contribute to weight gain. That said, high GI foods can help with energy recovery after exercise or offset hypoglycemia. Long-distance runners and other endurance athletes favor foods that are high on the glycemic index for this reason. Conversely, diabetics and pre-diabetics should concentrate on low GI foods to help them control blood sugar.
Sugars are the simplest form of carbohydrates, known as monosaccharides and disaccharides. Monosaccharides include glucose, fructose, and galactose (milk sugar). Disaccharides, such as sucrose, maltose, and lactose, are made up of two monosaccharides put together. The term ‘sugar’ typically refers to the disaccharide sucrose, a combination of glucose and fructose made naturally in all green plants via photosynthesis.¹
Sugars provide energy to the body and can keep your metabolism stable. We all need regular healthy sugar intake to function. However, too much or too little sugar can be harmful, causing hypoglycemia, acne, dental problems such as cavities, and even metabolic conditions such as obesity and diabetes. Knowing the difference between natural and added sugars is critical in learning how to manage your sugar intake.
Natural sugar vs. added sugars
Fruits, vegetables, and dairy products all contain natural sugars. A banana or glass of milk will provide fructose or lactose, but you’re also getting fiber and nutrients such as vitamins and protein.² These natural forms of sugar are processed more slowly, keeping your blood sugar (glucose levels) stable over longer periods. This keeps your energy levels steady and staves off a sugar rush or crash. Consuming natural sugar is more sustainable and healthier for your body than added sugars.
Added sugars are found in processed and prepared foods, such as sweetened beverages, cereals, snack foods, candy, jams, curds, desserts, pastries, and other baked goods.³ Added sugars are processed much more quickly and, if not being used, are stored in the body as fat.² Foods with added sugars are often high in calories and low in fiber and nutrients, so you won’t feel very full after eating them, even if they have a meal’s worth of calories. Added sugars are more likely to cause big spikes and drops in your blood sugar; the crash after eating or drinking something high in added sugars can make you feel hungrier and cause you to overeat. Due to their high caloric density and high sugar content, they can cause a lot of damage to your body’s metabolic systems.
Sugary drinks such as juice, soda, and even certain coffee drinks are responsible for a lot of the added sugar in the American diet. These beverages can contain up to 65 grams of added sugar. Often, this added sugar is high-fructose corn syrup, which is a popular and cheap sweetener.³
Along with knowing the difference between natural and added sugars, learning about the caloric density of sugar, how to read food labels, the glycemic index of foods, and daily percentage values is also important in managing sugar intake.
The American Heart Association recommends limiting added sugar intake for all ages. One teaspoon of sugar weighs about four grams and equals about 16 calories. Here are the daily recommendations for men, women, and children:
- Women: 100 calories, six teaspoons, or 24g
- Men: 150 calories, nine teaspoons, or 36g
- Children ages 2-18: less than six teaspoons
Children should also be limited to less than eight ounces of sugary drinks per week. For individuals with existing health conditions such as diabetes, these limits might be even more strict.³
Nutrition labels
Knowing how much added sugar you can safely consume is one thing, but navigating the nutrition labels on foods is another. In 2016, the FDA mandated changes to the nutrition labels of packaged foods and drinks. This went into effect in 2021, and the label now features added sugar content under the total sugars section.⁴
The label also features the percent Daily Value (% DV), which calculates how much of a nutrient contributes to the daily recommended allotment. The daily value of added sugar is 50g per day in a standard 2,000 calorie diet. For example, if one serving of a brand of cookies contains 25g of added sugars, the daily value would show as 50%. If you consume a serving of these cookies, you’ve eaten half the recommended daily amount of added sugar. Knowing this can make it easier to adjust your sugar consumption that day to ensure it doesn’t go over 50g.⁴
If you have a stricter limitation on added sugar, you’ll need to make more adjustments. To keep things simple, 5% DV or less of added sugar is considered low, and 20% DV and above is considered high, making it even easier to choose the right snack or drink based on your health needs.⁵
Sugar by any other name would taste as sweet
Sugar goes by even more names than the scientific classifications we’ve already mentioned. Here are some ingredients that sound different (or maybe even healthy) but in reality are just added sugars:³
- Brown rice syrup
- Agave nectar
- Honey
- Corn syrup
- High-fructose corn syrup
- Molasses
- Raw sugar
- Evaporated cane juice
- Invert sugar
- Cane sugar
- Maple syrup
- Brown sugar
The following chart provides GI levels for more than 60 foods as derived from a comprehensive analysis of more than 200 scholarly articles devoted to studying glucose and GI impact on human subjects. The studies used different baselines for their scale, with some using basic glucose and others using common foods like white bread or rice. For this chart, all values reflect glucose as a basis for scaled comparison.
| Food | Glycemic index score (scale of 0-100) |
|---|---|
| High-carbohydrate foods | |
| White wheat bread* | 75 ± 2 |
| Whole wheat/whole meal bread | 74 ± 2 |
| White rice, boiled* | 73 ± 4 |
| Unleavened wheat bread | 70 ± 5 |
| Brown rice, boiled | 68 ± 4 |
| Couscous† | 65 ± 4 |
| Wheat roti | 62 ± 3 |
| Udon noodles | 55 ± 7 |
| Rice noodles† | 53 ± 7 |
| Specialty grain bread | 53 ± 2 |
| Sweet corn | 52 ± 5 |
| Chapatti | 52 ± 4 |
| Spaghetti, white | 49 ± 2 |
| Spaghetti, whole meal | 48 ± 5 |
| Corn tortilla | 46 ± 4 |
| Barley | 28 ± 2 |
| Breakfast cereals | |
| Cornflakes | 81 ± 6 |
| Instant oat porridge | 79 ± 3 |
| Rice porridge/congee | 78 ± 9 |
| Wheat flake biscuits | 69 ± 2 |
| Millet porridge | 67 ± 5 |
| Muesli | 57 ± 2 |
| Porridge, rolled oats | 55 ± 2 |
| Fruit and fruit products | |
| Watermelon, raw | 76 ± 4 |
| Pineapple, raw | 59 ± 8 |
| Mango, raw† | 51 ± 5 |
| Banana, raw† | 51 ± 3 |
| Orange juice | 50 ± 2 |
| Strawberry jam/jelly | 49 ± 3 |
| Peaches, canned† | 43 ± 5 |
| Orange, raw† | 43 ± 3 |
| Dates, raw | 42 ± 4 |
| Apple juice | 41 ± 2 |
| Apple, raw† | 36 ± 2 |
| Vegetables | |
| Potato, instant mash | 87 ± 3 |
| Potato, boiled | 78 ± 4 |
| Pumpkin, boiled | 64 ± 7 |
| Sweet potato, boiled | 63 ± 6 |
| Potato, french fries | 63 ± 5 |
| Plantain/green banana | 55 ± 6 |
| Taro, boiled | 53 ± 2 |
| Vegetable soup | 48 ± 5 |
| Carrots, boiled | 39 ± 4 |
| Dairy products and alternatives | |
| Rice milk | 86 ± 7 |
| Ice cream | 51 ± 3 |
| Yogurt, fruit | 41 ± 2 |
| Milk, full fat | 39 ± 3 |
| Milk, skim | 37 ± 4 |
| Soy milk | 34 ± 4 |
| Legumes | |
| Lentils | 32 ± 5 |
| Chickpeas | 28 ± 9 |
| Kidney beans | 24 ± 4 |
| Soya beans | 16 ± 1 |
| Snack products | |
| Rice crackers/crisps | 87 ± 2 |
| Popcorn | 65 ± 5 |
| Soft drink/soda | 59 ± 3 |
| Potato crisps | 56 ± 3 |
| Chocolate | 40 ± 3 |
| Sugars | |
| Glucose | 103 ± 3 |
| Sucrose | 65 ± 4 |
| Honey | 61 ± 3 |
| Fructose | 15 ± 4 |
Data are means ± SEM.
* Low-GI varieties were also identified.
† Average of all available data.
Remember that glycemic index values are based on aggregated research, as individuals may respond with slight differences when exposed to the same foods. It’s also true that a wide range of variables influences the glucose content of natural foods; even two apples grown on the same tree and harvested simultaneously can have unequal distribution of sugar between them.
GI values are still helpful for anyone looking to maintain healthy blood sugar levels or provide targeted benefits in conjunction with exercise or the treatment of specific diseases. But both glycemic index and glycemic load information have their limits, and you should speak with your doctor about any drastic changes to your diet before you begin to experiment.
[1] Sugar vs. Sugars- Clearing up Confusion. (n.d.). The Sugar Association. https://www.sugar.org/sugar/sugars/
[2] Understanding Natural Versus Added Sugars – Center for Healthy Eating and Activity Research. (2021, February 26). Chear. https://chear.ucsd.edu/blog/understanding-natural-versus-added-sugars
[3] Added Sugar. (2013, August 5). The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/carbohydrates/added-sugar-in-the-diet/#:~:text=The%20AHA%20suggests%20a%20stricter
[4] Nutrition, C. for F. S. and A. (2020). Added Sugars on the New Nutrition Facts Label. FDA. https://www.fda.gov/food/new-nutrition-facts-label/added-sugars-new-nutrition-facts-label
[5] Boston, 677 H. A., & Ma 02115 +1495‑1000. (2021, June 29). Understanding Food Labels. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/food-label-guide/
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