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WHAT IS THE DIFFERENCE BETWEEN THE INSULIN INDEX AND THE GLYCAEMIC
INDEX
What is the difference then between the insulin index and the glycaemic index?
If you think we've made a mistake and that what we really mean is the glycaemic
index, you're wrong. We do mean the insulin index. Never heard of it? You're
not alone. Insulin Indices are only really begining to be fully understood now
and the popularity amongst the athletic world is taking it by storm. Although
insulin indices are not new, they've been ignored in health and fitness for
far too long.
So what is the difference between the two ratings for foods - glycaemic and
insulin? Well, the popular glycaemic index is a measure of the speed at which
carbohydrates enter the blood after a meal. A high-glycemic index means that
blood sugar rises rapidly in response to a meal, while a low-glycaemic index
means that blood sugar rises very slowly. Traditionally, nutritionists thought
that the faster the carbs got into the blood, the bigger the insulin response.
So in an attempt to manage insulin, they recommended always eating low-glycaemic
foods. There was some rational thinking and logic behind this assumption - however
these general guideline rules have actually since been proven far from the truth.
What has been discovered by several studies since, have shown that some low
glycaemic index foods have huge insulin responses! So the correlation between
glycaemic index and insulin response breaks down with some foods. For example,
milk products have a very low glycaemic index. But they promote insulin responses
parallel to the highest glycaemic foods. So just as this food has a slow influx
of glucose into the blood stream - the stimulatory response of insulin is high
and rapid. So what's the deal? Well, it appears that there are several other
factors that determine insulin release besides carb content and the rate of
carb absorption.
This is why the insulin index was generated. This index actually measures insulin
response to a food. So rather than assuming insulin response is correlated with
carb absorption, these researchers decided to go ahead and measure it. And their
results were eye opening!
We have to realize that we use the insulin index not to condemn foods but to
decide when to eat them. The point that must be stressed is that the insulin
index helps us add information to the glycaemic index to make better food choices.
So using both indices is the way to go. It is not that one index is better or
more correct than an other index. Since milk products have a low GI but a high
II, these foods aren't optimal when you want to keep insulin low. Other example
foods or meal combinations for this situation are baked beans in sauce, meals
with refined sugars and fats, and meals that are protein and carbohydrate rich.
Each of these foods/combos have low GI scores but high II scores, none of which
are optimal for low insulin times. But remember, some times you want high insulin
so don't relegate these foods/combos to a dark corner of your nutritional closet.
Insulin can be as much an ally as an enemy when it comes to building muscle
and burning bodyfat.
Conversely, unprocessed fibrous grains and cereals as well as fruits and veggies
are great on both scales. In addition, most low-fat protein sources are also
great on both scales.
Studies by Holt et al (1996) and Ostman et al (2001) highlighted some of these
differences between glycaemia and insulinemia. Interestingly, while the glycaemic
and insulin indices of many foods were similar, some foods caused unpredicted
responses. Foods like yogurt and milk had relatively low-glycaemic indices,
but very high insulin indices. White and brown rice, on the other hand, had
high-glycemic indices, but low insulin indices. The point here is that if you
want to effectively manage body composition, you should choose your carbohydrates
based on both the glycaemic and insulin indices. Unfortunately, there are only
limited amounts of insulin data out there, leading us to continue to rely in
some cases only on the glycaemic index.
For example, whole wheat bread measures approximately 60 on the GI, but what
do you think would happen if you ate five or six slices with every meal? Just
because it's relatively low as far as carb GI rankings are concerned, it doesn't
mean you can eat all you want and not cause your insulin to go into overdrive
in production. You have to not only consider the GI ranking, but also you need
to keep in mind the total carbohydrate volume you ingest. It is important to
note how GI scales were developed and the fact that only 50g of the Carbohydrate
source consumed in the testing. This example illustrates why we need not only
the GI but also the II.
Used together, the GI and II indices can help you plan meals according to your
needs (i.e. high or low insulin release). For instance, if you're trying to
get lean you'll want to keep insulin at bay most of the day except immediately
after training when you want to spike it through the roof to shuttle glycogen
and protein back into your starved muscles. Maintaining steady and stable low
insulin levels always the process of fat burning to take place. As soon as insulin
levels rise, fat burning grinds to a halt.
In this scenario you'd eat a combination of low GI and II foods throughout
the day. If, on the other hand, you're trying to bulk up and gain quality muscle,
you'll no doubt want to spike insulin several times throughout the day along
with a generous helping of protein. Shuttling amino acids into muscle cells.
Just how many grams of carbs you need a day for optimum performance is a debate
that most likely will never be settled. It's largely a matter of individuality.
You should plan your needs around the inbuilt nutrition calculator and fine
tune the requirements based upon your metabolic and body type.
As discussed in other sections of the website you will be familiar with the
principles of energy balance (calories in vs calories out), meal combinations
(the types of food you in and what you eat in relation to other foods you eat
at any given time) and you will know a little about individual physiological
responses to the foods that you eat (your metabolic insulin sensitivity and
carb and fat tolerances.).
Anybody who has trouble gaining muscle or losing fat can stop blaming their
genetics or their poor metabolism if only they understood and made proper use
of the insulin index and glycaemic index of food. Going stages further you can
learn your individualised metabolic type and body type and really get to grips
with the way that your body handles and processes foods.
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