Yet every once in a while, a concept within the nutrition field emerges that truly demands attention. Over a decade ago, the USDA’s “Food Pyramid” was one such concept because it helped eaters discover how many gaps existed in their typical daily diet. Now, as the Food Pyramid begins to take a new shape, and as the nutrition field works to establishes itself as the most important branch of health care in the 21st century, an invention called the Glycemic Index is taking center stage.
The Glycemic Index (GI) is not new; it has been around for more than 2 decades. Yet until recently, its exposure beyond the world of diabetes has been limited [i].
The Glycemic Index indicates how “high” or “low” blood sugar levels change in response to carbohydrate intake. A “high” Glycemic Index indicates carbohydrates with a swift breakdown, whereas a “low” Glycemic Index indicates carbohydrates with slow, gradual breakdown. Both terms are of equal importance to diabetics, because there are times with high Glycemic Index foods are required, and times where low Glycemic Index foods are required.
Indeed, the Glycemic Index itself is not new, but its application far beyond the borders of a diabetic dialogue is notable; especially for dieters.
People striving to lose weight often face a nemesis much tougher than establishing an exercise regimen or introducing healthier foods into their diet. The problem is one of energy. Many dieters are surprised – and disturbed – to learn that their diet program is causing them to lose more than inches and pounds: they are losing energy.
This is often expressed as a complaint, as in “I’m feeling weak”, or even “I can’t stay awake”. Many dieters and those advising them have erroneously chalked this up to a matter of attitude, or will power, or some non-biological cause.
The plain truth is that many dieters have been oblivious to the Glycemic Index, and hence, to the fact that many of the diet foods they have eaten – or are eating right now – score very high Glycemic Index levels. As such, these foods are providing a quick boost to blood sugar levels, and then setting up the dieter for the inevitable fall. This is because high GI foods typically increase blood sugar values, which in turn trigger the hormone insulin to clear sugar from the blood. Since blood sugar (a.k.a. glucose) largely dictates the body’s energy levels, it stands to reason that this process manifests as an initial boost in energy, and then as a depletion of energy. This rise and fall of blood sugar – and energy – is often described by dieters using a “roller-coaster” analogy: one minute they feel confident and strong, and the next, they are about to pass out and require some kind of stimulant in order to make it through the day.
Regrettably for many dieters, that stimulant is usually more high Glycemic Index foods, such as sugary snacks or soft drinks. It is easy to see how this experience can lead an individual to stop dieting. After all, before the diet, the individual was merely gaining weight. On the diet, the individual is gaining weight and is exhausted for most of the day. It is better to quit the diet.
The above scenario only takes place, however, when a dieter unwittingly eats high Glycemic Index foods. Research has shown that low Glycemic Index foods, which raise blood sugar levels much more gradually than high Glycemic Index foods, are very helpful for dieters [ii]. This is because a dieter will experience less of a “roller-coaster” ride while on the diet, and furthermore, will be less inclined to snack because energy in the form of blood glucose is being released slowly and gradually. Low Glycemic Index foods are much more efficient sources of energy than high Glycemic Index foods, because the body needs less insulin to convert food into energy [iii].