Glycemic Index: Useful, or not so much?


Glycemic Index: Useful, or not so much?

Glycemic Index: Useful, or not so much? – Jason Yule

So I was reading an article on the Glycemic Index the other day, and it brought up some really good points about the system and why it may not be as useful as the mass media likes to portray. I’ll get into that shortly. If you aren’t familiar with the Glycemic Index, it’s basically this concept that there are different qualities of carbohydrates based on how quickly they break into sugar and enter our blood stream. The faster foods break down, the bigger impact they have on our hormones and insulin production, and are perceived to be less body friendly. But today isn’t about learning the GI, if you aren’t familiar with it, there are tons of resources to learn about it pretty quick, so go study up. Today is going to be about issues with the system intended for people who are already familiar with the Glycemic Index.

Let’s begin with how the index is actually created – scientists have a participant fast just like you would for any normal blood test. They have the participant eat 50g of whatever carbohydrate they want to test, let’s say an apple for now. They measure the blood sugar levels before consumption and then after consumption every 15 minutes until the blood sugar levels return to normal. The total blood sugar deviation from normal is the glycemic index number for the apple. So the scientists do this with every carbohydrate source, and voilà, the glycemic index is created.

Awesome, now we have a list of all carbohydrates and which ones are going to be better for us to eat. As they say, the low GI carbs good and high GI carbs are bad. But here’s what they decided didn’t need to be shared – the results of the Glycemic Index are totally stand-alone and independent of one another, and VERY VERY VERY limited in scope. What I mean is, they don’t test carbs together. Or with other food sources. Or in more than 50g increments. Think about it, when is the last time you’ve only had 50g of carbs, totally fasted, without any other food with it? Probably the ONLY time I can think of is eating some fruit right when you wake up. Other than that? We have no idea if the glycemic index still works, if the results are different, etc.

I’m no biologist, but it stands to reason that if I eat a higher GI carb with some protein and some healthy fat, its probably not going to impact my blood sugar levels quite as significantly as the GI system makes it seem. When we eat protein, Glycogon is released into the blood stream, which is a counter to insulin. Fats also release some other hormones. So we can reasonably assume that most of the time we are going to have some buffer room, assuming we aren’t eating only carbohydrates, because that wouldn’t be smart of course.

And then of course, what happens if we eat more than 50g of carbs at a time? I’m eating about 225g of carbs at each meal, so do I just multiply linearly? Or is it exponential? Or maybe it isn’t even perfectly correlated. Maybe as we eat more of a carb source, it impacts our blood sugar levels less and less. We can’t answer these questions because we don’t really know.

So what am I trying to say? Don’t use the Glycemic Index? Ignore it? I mean, not totally. It’s still a great resource to see which carb sources are super simple versus which ones are super complex, but at the end of the day don’t stress out about the GI level of your foods. Mix it up, have some simple sugars (fruits), a bit of less simple starches, and then a whole bunch of complex carbs (veggies). Just don’t complicate it too much. Like CrossFit says, “Eat whole foods, meats & veggies, nuts & seeds, some fruit, little starch, and no sugar.” If you follow that, don’t stress out, and don’t complicate it! Just eat a well rounded and varied diet J