Glycemic load

Glycemic load

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The glycemic load is a ranking system for carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 content in food portions based on their glycemic index
Glycemic index
The glycemic index, glycaemic index, or GI is a measure of the effects of carbohydrates on blood sugar levels. Carbohydrates that break down quickly during digestion and release glucose rapidly into the bloodstream have a high GI; carbohydrates that break down more slowly, releasing glucose more...

 (GI) and a standardized portion size of 100g. Glycemic load or GL combines both the quality and quantity of carbohydrate in one number. It is the best way to predict blood glucose values of different types and amounts of food. The formula is: GL = GI x the amount of available carbohydrate in a 100g serving / 100.

The glycemic load assesses the impact of carbohydrate consumption using the glycemic index but takes into account the amount of carbohydrate that is consumed. GL is a weighted GI value. For instance, watermelon
Watermelon
Watermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...

 has a high GI – but watermelon does not actually contain much carbohydrate, so the glycemic effect of eating it (and therefore its GL) is actually relatively low.

A GL greater than 20 is considered high, a GL of 11-19 is considered medium, and a GL of 10 or less is considered low. Foods that have a low GL almost always have a low GI. Foods with an intermediate or high range GL range from a very low to very high GI.

The rationale for establishing glycemic load as an important characteristic of a food is based on the fact that a larger amount of a food with certain glycemic index that contains few available carbohydrates would have the same effect on blood sugar
Blood sugar
The blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. Normally in mammals, the body maintains the blood glucose level at a reference range between about 3.6 and 5.8 mM , or 64.8 and 104.4 mg/dL...

 as a smaller amount of a food that has the same glycemic index but a higher carbohydrate content. Glycemic Load is the product of the Glycemic Index and the grams of available carbohydrate in a 100g serving (GL = GI × available Carb grams). For example, white rice has a somewhat high GI, so eating 50g of white rice at one sitting would give a particular glucose curve in the blood, while 25g would give the same curve but half the height. Since the peak height is probably the most important parameter for diabetes control
Diabetes management
Diabetes is a chronic disease with no proven cures but a lot of research is underway. It is associated with an impaired glucose cycle that alters the patient's metabolism. Management of this disease may include carefully managing diet, exercising, taking oral diabetes medication, using some form...

, multiplying the amount of carbohydrates in a food serving by the glycemic index gives an idea of how much effect an actual portion of food has on blood sugar level.

One recent study has questioned the value of using glycemic load as a basis for weight loss programmes.

Glycemic load appears to be beneficial in dietary programmes targeting metabolic syndrome, insulin resistance, and weight loss; Studies have shown that sustained spikes in blood sugar and insulin levels may lead to increased diabetes risk. The Shanghai Women's Health Study concluded that women whose diets had the highest glycemic index were 21 percent more likely to develop type 2 diabetes than women whose diets had the lowest glycemic index. Similar findings were reported in the Black Women's Health Study. A diet programme that manages the glycemic load aims to avoid sustained blood sugar spikes, and can help avoid onset of type 2 diabetes. For diabetics, glycemic load is a highly recommended tool for managing blood sugar.

Glycemic load for a single serving of a food can be calculated as the quantity (in grams) of its carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 content, multiplied by its GI, and divided by 100. For example, a 100g slice serving of watermelon
Watermelon
Watermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...

 with a GI of 72 and a carbohydrate content of 5g (it contains a lot of water) makes the calculation 5·72/100=3.6, so the GL is 3.6. A food with a GI of 100 and a carbohydrate content of 10g has a GL of 10 (10·100/100=10), while a food with 100g carbohydrate and a GI of just 10 also has a GL of 10 (100·10/100=10).

The data on GI and GL listed in this article is from the University of Sydney
University of Sydney
The University of Sydney is a public university located in Sydney, New South Wales. The main campus spreads across the suburbs of Camperdown and Darlington on the southwestern outskirts of the Sydney CBD. Founded in 1850, it is the oldest university in Australia and Oceania...

(Human Nutrition Unit) GI database.

The GI was invented in 1981 by Dr Thomas Wolever and Dr David Jenkins at the University of Toronto and is a measure of how quickly a food containing 25 or 50 grams of carbohydrate raises blood glucose levels. Because some foods typically have a low carbohydrate content, Harvard researchers created the GL, that takes into account the amount of carbohydrates in a given serving of a food, and so provides a more useful measure.

List of foods and their glycemic load, per 100g serving


All numeric values provided in the table are approximate.
Food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

 
Glycemic index
Glycemic index
The glycemic index, glycaemic index, or GI is a measure of the effects of carbohydrates on blood sugar levels. Carbohydrates that break down quickly during digestion and release glucose rapidly into the bloodstream have a high GI; carbohydrates that break down more slowly, releasing glucose more...

 
Carbohydrate
content
(% by weight)
Glycemic Load Insulin index
Insulin index
The Insulin Index is a measure used to quantify the typical insulin response to various foods. The index is similar to the Glycemic Index and Glycemic Load, but rather than relying on blood glucose levels, the Insulin Index is based upon blood insulin levels...

Baguette
Baguette
A baguette is "a long thin loaf of French bread" that is commonly made from basic lean dough...

, white, plain (France)
95 (high) 50
Banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....

, Mean of 10 studies
52 (low)–± (low) 20 10–± ±
Carrots, Mean of 4 studies 47 (low)
Corn tortilla
Tortilla
In Mexico and Central America, a tortilla is a type of thin, unleavened flat bread, made from finely ground maize...

 (Mexican)
52 (low) 48
Potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

, Mean of 5 studies
50 (low)–± (high) 9.3–± ±
Rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

, boiled white, mean of 12 studies
64±9 (medium)–± (high)–83±13 (high)–93±11 (high) 77.5–79.9–79.6 ±–±–±–± 40±10–±–67±15-67±11
Watermelon
Watermelon
Watermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...

72 (high) 5

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