Could someone explain GI in layman's terms?

Stella777

I was looking up Glycemic Indexes of some foods, and was surprised. Some of them seem counterintuitive to me. For example peanut M&Ms were listed in the low GI category. Millet was on the high GI list? Could someone give me a basic explanation?

EileenG

And that is exactly why I think the whole GI thing is a bit of a con.

Anyway, GI stands for Glycemic Index, which is the speed at which a food turns to sugar in your body. The highest (in theory) is 100, which is glucose. Table sugar and cornflakes are around 70.

It's a bit more complicated than that, because the speed at which insulin starts to take the glucose out of your blood is also a factor, but let's keep it simple.

Anyway, in general, low carb/high fiber foods tend to have a low GI. So things like broccoli are low GI and a general all round good food. But if you take a food like a Snickers bar, that has a nuts in it as well as a load of sugar, the speed of absorption is much lower. But it continues to release sugar for a long time, and it still has a ton of calories.

Also, grains in general tend to have a high GI. Grains, even wholegrains, tend to dump a lot of glucose into your body quickly. Eating grains with a protien or fat source lowers the rate of absorption.

brainyneuron

Sorry that this is a bit rushed as I've got to head to work in a minute!

There were a few problems with GI ratings so the new index that nutritionists are using is GL (Glycemic Load).
From Patrick Holford book:
-GI is a qualitative measure that tells you whether the carbohydrate it contains is 'fast or slow' releasing. it doesn't tell you, however, how much of the food is carbohydrate. Carbohydrate points or grams of carbs are quantitative measures that tell you how much of the food is carbohydrate, but the don't tell you what that carbohydrate does to your blood sugar. GL of a food is the quantity times the quality of its carbohydrate, and that is the best way of telling you how much weight you will gain if you choose that food.
-How a food is cooked can change the GL rating.
-A food's fibre lowers its GL.
-40GL a day is the target (with allowances for higher activity levels (exercise/active job etc)
A bowl of porridge is 2 GL while a bowl of cornflakes is 21GL :eek:

Pembily

brainyneuron wrote: »

Sorry that this is a bit rushed as I've got to head to work in a minute!

There were a few problems with GI ratings so the new index that nutritionists are using is GL (Glycemic Load).
From Patrick Holford book:
-GI is a qualitative measure that tells you whether the carbohydrate it contains is 'fast or slow' releasing. it doesn't tell you, however, how much of the food is carbohydrate. Carbohydrate points or grams of carbs are quantitative measures that tell you how much of the food is carbohydrate, but the don't tell you what that carbohydrate does to your blood sugar. GL of a food is the quantity times the quality of its carbohydrate, and that is the best way of telling you how much weight you will gain if you choose that food.
-How a food is cooked can change the GL rating.
-A food's fibre lowers its GL.
-40GL a day is the target (with allowances for higher activity levels (exercise/active job etc)
A bowl of porridge is 2 GL while a bowl of cornflakes is 21GL :eek:

Yeah I have his book and a baked potato (my fav) is the worst way to cook a potato!!! Think I will give it a read over the weekend and get in the mindset again!! I will report back Stella!

cruizer101

Also just to add you should really work out the GI of a whole meal rather than its single constituents. So if you eat a low GI for with your high GI food it will slow down the overall rate of absorbtion.

eg.. Serving of Cornflakes: 24g of Carb GI 80
Milk : 11.9g of Carb Gi 31

The percentage of carb from Cornflakes is 67% and 33% from milk, so multilpy those by GI to give overall GI of 63

So the bowl of cronflakes isn't as bad as it was orginally (note: I might have my ratio of flakes to milk a bit on the milky side but you get the idea)

In general proteins and fats are low GI it takes the body a long time to process them. Also most processed foods will have high GI as the processing often makes them easier for us to digest.

Finally just on the 100 being highest GI, I recently heard that dates in fact have a GI of 103, how this works I'm not too sure but there you go.

El_Dangeroso

I'd recommend anyone interested in the GI diet to buy themselves a glucose meter. They are really cheap and will give you the exact GI index of a meal that is completely personal to you.

For example, the GI of porridge is measured as low. Not in me it isn't. My blood sugar soars to 170mg/dl after a bowl of porridge which is very high! When I have a potato with nothing on it it barely reaches 120mg/dl despite potato having a much higher GI. Weird eh?

Pembily

Temple_Grandin wrote: »

I'd recommend anyone interested in the GI diet to buy themselves a glucose meter. They are really cheap and will give you the exact GI index of a meal that is completely personal to you.

For example, the GI of porridge is measured as low. Not in me it isn't. My blood sugar soars to 170mg/dl after a bowl of porridge which is very high! When I have a potato with nothing on it it barely reaches 120mg/dl despite potato having a much higher GI. Weird eh?

That is nuts - I find sometimes I eat potato and I can barely move I am so exhausted but I can't find a link - I think if I eat only potato with carbs my energy plummets!! Think I might get one of those to find my trigger foods!

Iristxo

Lidl still has them blood glucose monitors, I saw them yesterday in the one in Rathfarnam. 19 euros a pop.