Glycemic Index Diet
What Affects It?
A glycemic index diet such as the " GI Diet " and the " Glycemic Impact
Diet " make use of the nature of low GI foods to help with weight loss (eg.
require less insulin and are often more filling). People with diabetes are also
encouraged to make frequent low GI food choices to aid blood sugar. BUT. .
. a low GI diet may not be what you think it is.
People have erroneously made the low glycemic index diet synonymous with a
diet that contains no processed foods. However . . .
Processing is only 1 factor that
affects glycemic index.
Many processed foods are great on a
low glycemic index diet. Like . . .
Converted Rice. You might know it as "Uncle Ben's".
It's processed and slow. Bran Buds and All Bran are processed and very slow.
(But not the All Bran Flakes - they're fast).
So what affects the glycemic index of foods?
Well, lots of things. Not just food processing, as you already know. And of course, no matter what
you find in the list below, there are always exceptions to the rules. Here are
some of the things that determine the GI of a food to see if it is appropriate
for a low glycemic index diet.
- Processing. It pre-cuts glucose chains into
tinier units that digest quicker.) But not always.
- Acid. Like vinegar - it slows the rate at which food leaves the
stomach. So sour dough bread is slower than most white bread. WARNING - it's
also bigger. So don't take this as an excuse to eat honking pieces of it.
- Type of carbohydrate. Fructose, lactose must change into glucose so are
slower - like milk, yogurt and most fruits.
- Structure of carbohydrate. Some starches have tightly packed glucose
chains (amylose) that are harder to digest and therefore "slower"
eg. lentils. Others have
looser packed glucose chains (amylopectin) that are easier for the digestive enzymes to
get at are "faster" to digest- like sticky rice. There
are about 2000 varieties of rice; the amount of amylose and amylopectin
varies between them. This is why low glycemic index diets suggest specific
varieties of rice like Basmati rice or "converted" rice, which are
both slow.
- Cooking method (Go figure. But this doesn't apply to everything.)
Boiled potatoes are slowish generally accepted in moderation in a low
glycemic index diet whereas baked potaoes have a high GI. Some of this
is also due to the brand of the potato.
- Cooking time or gelatinization. The longer you cook some
foods, like pasta, the more of the starch "gelatinizes". This
makes it more accessible to digestive enzymes in the gut and it enters the
blood stream faster. So really soggy pasta is faster getting in. Whereas
"al dente" pasta is slower getting in. Some foods naturally
gelatinize.
- Soluble fibre - it's the gummy, viscous fibre. It slows the
absorption of carb from the gut.
- Fat and protein content - these slow the carbs down because it
slows the emptying of the stomach (otherwise known as gastric emptying).. But as a rule, most
people don't want excessive fat or animal proteins in their diet. Let me
rephrase that - most people would not BENEFIT from excessive fat or animal
proteins (cause, like. . .umm . . I want it. I just won't benefit
from having it.)
- Mixed meals - whatever else you eat at the meal affects the
GI of the meal.
Confused?
Don't be.
Try these simple tricks for making more low glycemic index diet choices.
Tips
and Tricks for a Low Glycemic Diet
A
free list of low glycemic index foods.
10
benefits of a low glycemic diet
And remember, the glycemic index is only one element to look at when choosing foods. Please
don't consider a low glycemic diet to be the be-all and end-all. We (OK,
you got me. "We" means dietitians like myself) look at foods for numerous elements
- calories, fats, antioxidants, fibres, flavinoids, vitamins, minerals . .
. glycemic index is just one more. Ahh, yes.
Portions matter too. I'd hate to see you make the mistake of eating hoards of a
low glycemic index bread at one sitting.
References:
The Glucose Revolution: The Authoritative Guide
to the Glycemic Index-The Groundbreaking Medical Discovery (Paperback) by Thomas
M.S. Wolever MD, PhD, Jennie Brand-Miller PhD, Kaye Foster-Powell.
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