Glycemic index and obesity

As I’ve discussed in the past, glycemic index (GI) is a measure of how fast food is absorbed into the blood stream. Foods that are absorbed slowly have a low GI and foods that are absorbed fast have a high GI.

But, here’s the kicker — GI measurement is based on foods being eaten by themselves, which almost never happens. Once you mix foods and end up eating a combination of protein, carbohydrate and fat, the individual GIs of each food no longer applies to how fast the entire meal is absorbed.

But, that doesn’t stop researchers from doing studies on GI.

Here is the conclusion from a GI study published in the October issue of the American Journal of Clinical Nutrition:

*** A high glycemic index diet correlates with greater waist circumference, body weight, and percentage of body fat in women — but these correlations are not seen in men. ***

So what the heck are we supposed to learn from this???

Isn’t it obvious? If you’re a man, you can live primarily on donuts and juice (foods classified as having a high GI) and never have any problems with your weight. But, if you’re a woman, you better not get near these foods.

I’m clearly being sarcastic. You can’t come to this conclusion from this study. In fact, you can’t come to any conclusion.

Why? Here are just some of the reasons:

1. The study implies that the GI of the women’s diet CAUSED the higher weight and fat levels. That’s just not true. Correlations (which is what they found in this study) don’t say anything about cause and effect.

2. Glycemic index of individual foods is an interesting concept but is almost impossible to apply in daily life. GI has only been measured on a few foods; GI is not listed on a product’s food label so memorization or carrying a reference text with you is the only way to know the GI of each food; the measured GI of a food changes with how it is cooked, prepared and chewed; the GI of individual foods does not apply when foods are combined.

3. Even thought the different results between men and women has no explanation, the study implies that women need to be concerned about GI and men don’t.

Bottom line — this study is just another example of the information presented by the media about weight-loss and nutrition that creates more confusion than help — and that actually contributes to the world’s “obesity crisis.”

Allen Oelschlaeger
Author of Finally, the Straight Scoop About Weight, Nutrition, and Fitness