I just posted this very long comment over at Big Fat Deal in response to a thread about the recent study purporting to show that lower the GI of a diet isn’t helpful.

Needless to say, this is stressing folks out. And in my quick review, I’m not so sure the press has gotten this right. And I hope someone like Regina Wilshire will provide a take on this.

The full response after the break.

The glycemic index is the food equivalent of the BMI; it’s a measure, but not particularly a good one, as it doesn’t take into account the volume of food, what happens when you eat other foods, how the food is prepared, and so on.

I think the glycemic load is an improvement, since it does account for volume (see http://www.mendosa.com/gilists.htm for a nice description of GL and http://www.glycemicindex.com for a great GL database).

Also, I wouldn’t categorize South Beach as a GI diet. Yes, South Beach recommends that the carbs you eat are on the lower end of the GI/GL scale, which, like spaceling said, is a good thing, since it points you in the direction of healthier foods.

But IMO, South Beach is much more than a GI diet. It’s really a low/managed carb approach, and I think that is what makes it successful. The CSPI calls South Beach a “healthy version of Atkins diet that’s backed by solid evidence on fats and heart disease.”

Me? I like the South Beach concepts, but don’t have the patience for following it too closely, so I do my own variant (which I call SuperFoods Rx meets Volumetrics meets Rachael Ray).

Note too that the study you point to is a five-year study that measured folks’ blood sugar “tested their blood sugar levels twice during the study period.”

Huh?!?

If I’m reading this right (and I’m looking at the actual study abstract now), they measured the blood sugar of 1000 adults at the beginning of the study, had them do food diaries for five years and then measured the blood sugar of the 813 adults who returned at the end of the study.

The way they determined whether or not the diet was effective was to test their blood sugar after fasting (prior to exam presumably) and two hours after ingesting 75g of glucose.

Now, I’m not a scientist (nor do I play one on TV :), but IMO, this completely misses the point of the GI/GL concept, which is blood sugar levels shortly after ingestion. Not five years later.

Or am I missing something here?