The Glycemic Index (GI) and the Glycemic Load (GL) of carbohydrates can often be heard about in the context of diet & nutrition. Diets use the GI and GL values too to determine meal plans for healthy diets and for weight loss purposes. Let’s see what is the difference between GI and GL and how to use these values to define which foods are healthier for us to consume.

Starting Point: Simple and Complex Carbs

Carbohydrates can be classified as either simple or complex. Carbohydrates are simple if they are composed of one or two simple sugars in the molecule and they are complex if they are composed of long chains of the simple sugar, glucose. Based on a simplistic categorization, sugars are simple carbs while starches are complex carbs.

In the past, medical practitioners assumed that eating more complex and less simple carbohydrates was beneficial for humans. It was assumed that the consumption of starchy food (complex carbs) would lead to smaller increases in blood glucose levels than foods containing simple carbs.

The Glycemic Index

The Glycemic Index is the cornerstone of a concept developed by Dr Thomas Wolever and Dr David Jenkins at the University of Toronto in 1981. The concept was developed within a research project that aimed to find out which carbohydrate is best to consume by diabetics.

According to the outcome of the Toronto research, carbohydrates that break down quickly during the digestion process and release glucose into the bloodstream with a fast pace have a high GI. Those foods that break down slowly and release glucose with a slower, more gradual pace into the bloodstream have a lower GI.

Rapid increases in blood glucose levels by the consumption of high GI foods are potent signals to the pancreas to increase insulin secretion. A few hours after eating such carbohydrates, the high insulin levels induced by consumption of high-glycemic index foods may cause a sharp decrease in blood glucose levels. In contrast, the consumption of low GI foods results in lower but more sustained increases in blood glucose levels and lower insulin demands on the pancreas.

The definition of the GI of food happens according to an elaborate and refined methodology used by Dr Wolever and Dr Jenkins. It measures how quickly a food containing 25 or 50 grams of carbohydrate raises blood-glucose levels.

Based on the concept of the GI, a research team at the Harvard University developed the concept of the Glycemic Load.

The Glycemic Load

Glycemic Load is a similar concept to the GI. The idea behind GL is to simultaneously describe the quality and quantity of carbohydrate in a meal, or in an entire diet.

The GL takes into account the amount of carbohydrates in a typical serving of the food. In practice, the GL of a food is more specific as it tells us how much the given food portion raises blood glucose. It multiplies the GI of the food with the actual amount of carbohydrate that is consumed in the serving, in grams, and then divides this by 100.

According to this concept, if a food has a GL of one point, it raises the blood sugar by one gram of glucose. If a specific food serving has low GL, it implies that its GI is low too. However, if a food has a low GI, it may have higher GL, depending the amount consumed.

A full diet can be evaluated from the viewpoint of its GL, which is called “dietary GL”. The dietary GL is the sum of the GL-s for all foods consumed in the analysed diet. A low GL diet typically has less than 80 points per day. A medium GL diet is between 80 to 120 points per day while a diet is high in terms of GL if it is over 120 points per day.

Harvard University has an excellent table that contains GI and GL data for more than 100 commonly consumed food items. If you wish to analyse your diet, take a look at this useful resource: http://bit.ly/19fUWtk

The gluten-free diet seems to be the new health & nutrition trend. Celebrities claim to have achieved perfect figures thanks to following a gluten-free diet and weight loss programmes that are designed around the elimination of gluten. A number of sources suggest that the gluten-free diet boosts energy levels, improves digestion and enhances attention span. It is applied to manage conditions like irritable bowel syndrome, attention deficit hyperactivity disorder and autism.

As demand grows for gluten-free food, more and more packaged food is labelled as such. Restaurants also offer gluten-free items on their menus to satisfy growing demand.  Gluten-free cookbooks are published in an ever-growing number and thousands of gluten-free recipes can be found online.

The gluten-free diet is advertised as the new magic in the world of health and nutrition. Nonetheless, it is worth looking at gluten a bit more closely before jumping on the bandwagon.

What is gluten exactly?

Gluten is a type of nutritional composite which is composed of two different proteins, i.e. gliadin and glutenin. Gluten is found in the wheat endosperm, which is a type of tissue in seeds. It nourishes plant embryos in the course of germination. When food is prepared, gluten affects the elasticity of dough, thereby having an impact on the consistency of baked wheat products. It often gives a chewy texture to baked goods.

Gluten can be found in wheat, rye, barley, triticale (a cross between wheat and rye) and in other grains. Wheat products that contain gluten include bulgur, durum flour, farina, graham flour, kamut, semolina and spelt. Gluten-like proteins can also be found in maize and rice, which are also sometimes referred to as gluten.

Gluten can be found primarily in breads, cakes, pies, cookies, cereals and pastas. Beer, candies, ice-cream, French fries, packaged gravies, sauces, salad dressings, snack foods, packaged soups may also contain gluten. Sometimes gluten is used as a stabilising, thickening and binding agent and as an additive in packaged foods.

When is it justified to go gluten-free?

There is no scientific research that would support the widespread claims about the benefits of a gluten-free diet for those who do not have medical conditions that demand the elimination of gluten from their diet.

With regards to weight loss, a gluten-free diet can be misleading. If weight loss is achieved due to following a strict, gluten-free diet, it is probably due to the elimination of carbohydrates like bread and pasta. The weight loss in these cases tends not to be down to the elimination of gluten itself but to the lowering of carb intake related to the foodstuff that contains the gluten.

It is worth noting that sometimes a gluten-free diet may be even more calorific than a normal diet, as many gluten-free food items, primarily bakery products, are loaded with fat and sugar to impersonate the original qualities that gluten creates in baked goods.

Strict elimination of gluten is nonetheless crucial for those who suffer from gluten intolerance, aka coeliac disease. It is a condition that affects 0.5 to 1% of the population of the United States and the United Kingdom. Prevalence of this disease is assumed to be similar in other wheat-consuming countries globally. Gluten sensitivity is another condition that requires one to follow a gluten-free diet.

Gluten-related conditions

Coeliac disease is a chronic digestive disorder. The condition creates an immune response to gluten. This reaction is such that it damages the small intestine of sufferers, creating gastrointestinal distress (stomach cramps, diarrhoea, and bloating) and nutritional deficiencies, weight loss and fatigue. In untreated cases it can lead to intestinal cancer, infertility and osteoporosis.

Non-coeliac gluten sensitivity is even more common. It creates similar symptoms to those of coeliac disease, without damage to the intestine.

It is difficult to recognise both gluten intolerance and gluten sensitivity as symptoms can be different from one individual to the next. Gastrointestinal pain, fatigue, anemia, abdominal discomfort, bloating, excess gas or joint pain are amongst the many symptoms that can suggest gluten intolerance or sensitivity.

If you suspect that you may suffer from gluten intolerance or gluten sensitivity, consult your GP. Specialised blood tests examining antigliadin antibodies, endomysial antibodies, and anti-tissue transglutaminase antibodies are available to screen for these conditions. Sometimes a small intestinal biopsy is required for accurate testing for coeliac disease.

At the present time, the only available treatment to coeliac disease and gluten sensitivity is a gluten-free diet. Following a gluten-free diet requires careful meal planning and thorough nutritional understanding, as gluten-free foods are often nutrient-deficient.

Unless you are gluten intolerant or gluten sensitive, you’d be wise to not buy into hype surrounding the gluten-free diet. You may be far better off following a balanced diet consisting of fruit, vegetables, lean protein (preferably from vegan and vegetarian sources) and pulses, nuts and grains.