Four reasons to ditch the fixation with glycemic index

Although there were mutterings earlier too, half the reason carbs became a pariah nutrient for those looking for "health" and "thin waists" (and not necessarily in that order) was the brouhaha about glycemic index (GI) that caught us all by the scruffs of our necks when it was discovered by David Jenkins of the University of Toronto in 1981 - delineating our "what's healthy" mindset into before GI and after GI timelines. (GI measures how quickly carbohydrates in a food raise blood sugar levels; a higher rating on a scale of 0-100 means the blood sugar rises more quickly.) 

Suddenly after the publishing of these ratings, foods became good or bad depending on where they stood on the GI scale. Statements like "How can you eat the banana, it's high GI", or "Have brown rice not white (it has higher GI)" became commonplace. But now it is increasingly becoming clear that GI as a tool is overrated (we have whipped this one horse way too much) and it's time to ditch our obsession with it, or at least understand it in perspective. 

With "food" and "eating" and "health", things aren't and cannot be unidi-mensional. It's a complicated relationship, and a rather complex chemistry is at work, where multiple factors/nutrients work in tandem always - and GI is just one of them. So determining food quality just by GI number will be foolhardy, to say the least. For example, won't you miss out on the fibre and potassium loaded in the banana if you avoid it just because of its GI? And does eating more biscuits (compared to watermelon, which apparently has a high GI of 72) makes sense just because it rates lower on the GI scale?

Secondly it's a new science, still a work in progression. It is not cast in iron (yet), and is definitely not foolproof. Recently, food scientists discovered that potatoes (another pariah due to GI) has been rated wrongly on the scale (I'd pointed this out in last week's post, too). Carrots were berated for being high GI for long before this too was proved wrong, and they were found to be low GI (all thanks to the fibre in them). And now another new study by researchers at Harvard School of Medicine and John Hopkins University of Medicine published last year has found little evidence that foods high on the glycemic index are "bad" for heart health and/or increase our risk of diabetes, or even that they lead to weight gain. Suddenly all the carb haters crying hoarse propagating these theories are quiet.

Another important factor that everyone forgets to take into account is the portion size. Eventually what matters the most is how much of a particular food you eat. Japanese eat white rice all day, but eat a small bowl each time (and not a big plate full). Which is why, instead of GI, the concept of glycemic load (GL) seems more practical, as it takes into account both the GI of the food and the amount of carbohydrates in a portion (calculated by multiplying the GI by the amount of carbohydrates in grams in a serving of food). GL propagates the idea that a high GI food eaten in small amount would have the same effect on blood glucose levels as larger quantities of a low GI food. This surely makes more sense!

Finally, the most important flaw in the GI theory is the fact that foods are rarely eaten in isolation. And it is actually the combined GI of the meal that matters, and not of one food. For example a high GI food paired with a protein food brings the GI of the meal down: rice with dal, an egg or a cheese sandwich, or a few nuts along with your toast, and cornflakes with milk. Similarly overcooking pasta, rice and vegetables raises the glycemic load, so cook them al dente (firm) to keep the GL moderate. And the GI of the fruit too goes up as it ripens.

The bottom line here really is that while GI is an important tool, it is just one and not the "only" criteria to decide what food is fit to eat, and which to junk. So consider it, but don't dwell on it. And certainly don't beat yourself with the GI stick too much and ban all carbs. You need them!