GI diet: Know the GI level of the food you eat

Are you tired of hearing about low-carb this and low-carb that? No problem. Today Im going to tell you about slow-carbs.

According to a study that appears in the May 2005 issue of the American Journal of Clinical Nutrition, most of us can eat all the carbs we want - just so long as theyre slow. And the slower the better.

Slow vs. low
Ive actually covered slow-carbs in a previous e-alert, but without the catchy name. A slow-carb diet is essentially a diet that restricts carbohydrates that rate a high glycaemic index (GI).

A quick review: Low GI foods (such as meat and most fruits and vegetables) prompt a slow increase in blood sugar levels, while high GI foods (such as foods with added sugar, processed baked goods and starchy foods) produce a quick spike in blood sugar levels. A steady intake of high GI foods promotes a gradual insensitivity to insulin - the precursor of type 2 diabetes.

Researchers at Childrens Hospital in Boston (US) designed a study to test the effectiveness of a slow-carb, low-GI diet using two key measures: weight loss and cardiovascular disease risk.

Twenty-three obese subjects were divided into two groups. One group of 12 subjects followed a conventional low-fat, reduced calorie diet. The other group of 11 subjects followed a low-GI diet, avoiding starchy foods and consuming protein along with any carbohydrates they ate. In addition, subjects in the low-GI group were unrestricted in their calorie intake. They were allowed to eat their fill and snack between meals. Subjects in both groups were urged to exercise regularly, and they all received counselling to help them stick to their diet and exercise regimens.

After one year the results were dramatic: Low-fat diet subjects lost just over six percent of their body weight on average, while low-GI diet subjects lost an average of nearly eight percent of their body weight.

In addition, one of the key markers for heart disease was much improved by the low-GI diet. Low-fat dieters reduced their triglyceride levels by less than 20 percent on average. Subjects on the low-GI diet, however, reduced triglycerides by nearly 40 percent. Another heart health marker provided an impressive result. Concentrations of plasminogen activator inhibitor 1 (a coagulation factor that increases blood clot risk) increased by more than 33 percent among the low-fat dieters, but DECREASED nearly 40 percent in the GI-diet group.

Keep it complex 
Last year I predicted that the buzz about low-carb diets would eventually evolve into popular recognition of the glycaemic index as a logical dietary guide. I really wasnt going too far out on a limb with that prediction. The glycaemic index has been around for a while, and it provides a convenient way to sort out simple carbs from complex carbs.

In a nutshell, simple carbs are fast (high GI), and complex carbs are slow (low GI). If your diet includes mostly complex carbs, you wont put undue stress on your pancreas (the organ that uses insulin to remove sugar from the bloodstream). A high intake of simple carbs, on the other hand, prompts an over-secretion of insulin and, in time, a cycle of extreme blood sugar swings as the body desperately attempts to auto-regulate.

The problem is further complicated when the simple carbs come from refined sources (and they mostly do). Refining strips away natural fibre that slows the release of sugar into the system.

As for the glycaemic index, there are several sources on the Internet that estimate the GI value of different foods. One in particular - glycemicindex.com - provides a complete GI database. The slight drawback is that the database is sometimes specific about brand names, which are mostly Australian (the site is maintained by the University of Sydney). Nevertheless, the database offers an excellent guide for making low GI dietary choices.