What's up dudes and what's up ladies? Bryan here, and in this video we're gonna look at
the glycemic index and glycemic load, I'm going to show you how each of these is derived, benefits and
drawbacks of each of them, and some other factors that affect them. So, what is the glycemic index? It
is a way to analyze carbohydrate foods based on their impact on blood sugar levels. The GI ranks
carbohydrates on a scale of 0 to 100, based on how much they raise blood sugar levels after eating.
Foods with a high GI are rapidly digested and absorbed, and therefore cause large fluctuations
in blood sugar levels, lower GI foods are more slowly digested and produce gradual rises in
blood sugar levels. How is a foods glycemic index value determined? Well, after an overnight fast, a
group of 10 people are given a serving of a food item. This serving contains 50 grams of available
carbohydrates, available carbohydrates does not include the fiber content, after the food has been
consumed, blood sugar levels are measured every fifteen to thirty minutes over a two hour period.
These results are plotted on a graph. Next, the people are given 50 grams of carbohydrates of a
reference food, either white bread or pure glucose. The same process is followed and these results are
plotted. The area under the curve for the reference food is given a value of 100, the area under the
curve of the test food is then calculated as a percentage of the reference food area. Whatever
that percentage is, is its glycemic index value. This is how the glycemic index rates foods. Most
organizations use a high, medium and low rating scale. Carbohydrates with a glycemic index value
of 55 or less are rated as low, a medium value lies between 56 and 69 and a high value is 70 or more.
Now, let's look at glycemic load. Glycemic load is another way to analyze carbohydrate foods, it takes
into account portion sizes, while the glycemic index looks only at 50 gram carbohydrate amounts,
glycemic load looks at the available carbohydrates in a portion size. The glycemic load equation is as
follows, available carbohydrates in a portion size, times the glycemic index of the food, divided by
100. The scale for glycemic load is as follows, high equals 20 or more, medium is 11 to 19, and low is 10
and under. Let's look at a couple of examples, here we have a serving size of 1 cup of diced pineapple,
which contains 19 point five grams of carbohydrate and two grams of fiber, giving it 17.5 grams of
available carbohydrates. And here we have a serving size of one cup of watermelon, which contains about
11.5 grams of carbohydrate, and 0.6 grams of fiber. So, it has roughly 11 total grams
of available carbohydrates. Next, we have a serving size of two slices of white bread, which contains
about 24 total grams of available carbohydrates. The GI value of the pineapple is 66, watermelon
is 72, which puts it in the high GI category and white bread has a GI of 70. I'm going to put the
glycemic load calculations on the screen for you. We see that the glycemic load for the serving of
pineapple is eleven point five five, watermelon is seven point nine two, and white bread is sixteen
point eight. This would put the watermelon in the low glycemic load category and the pineapple and
white bread into the medium glycemic load category. So, as you can see, the glycemic load takes into
account the portion size. However, over eating any food will dramatically increase its glycemic load.
I'll put a couple of links in the description box below where you can see the glycemic index and
glycemic load of many different foods. The glycemic index and glycemic load are not foolproof, let's
take a look at ice cream. It has a glycemic index of 36, really good, a serving size of one cup yields a
glycemic load of about eleven point five two, so, a low glycemic index and a medium glycemic load, not
too bad. But why are these numbers so low? Well, when we look at the total profile of ice-cream, we see
it as 14 grams of fat, eight grams of saturated fat, in one serving, so, as the body digests it
the glucose release will be slower because the body has to break down the fat in addition to
the carbohydrates. This gives it a lower glycemic index. Other things that affect the food's glycemic
index value is how it's cooked, any cooking will raise the food's value however slow cooking will
not raise a glycemic index value nearly as much as fast cooking, such as microwaving. The more of
food has been processed the higher the glycemic index value will be, and what other types of foods
it is being consumed with, will affect its value as well. The glycemic index and glycemic load can be
useful in relation to blood sugar level spikes. However, because the food has a low glycemic
index or glycemic load value, this does not mean the food is healthy or unhealthy. The glycemic
index and glycemic load can be a helpful tool in evaluating food, however, it's only one tool. Look at
the fat content, the fiber content, look at how much processing the food has gone through, and how the
food was cooked. One last thing, many studies have shown that consumption of lower glycemic foods
has delayed the return of hunger and decreased subsequent food intake. Research continues on
that subject, as we always say here try and increase your whole food consumption, try and
minimize the processed foods, but don't be afraid to eat the food you love, just do it in moderation.