The Glycemic Index - Following a Low-GI diet

This is a long and convoluted topic that I'll try and make as simple as possible. I've read more books on the Low GI diet that I don't really have to think about it anymore. At first, however, it was really confusing and overwhelming. I'll try and provide the condensed version of what the Glycemic Index is and how following a Low-Glycemic Index Diet can be beneficial.

Here goes:
Glycemicindex.com defines it as: "...a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating".

What does this mean?  Well in essence the food scientists that figure this out rank foods on this scale.  100 being pure glucose (on most charts, sometimes 100 is white bread meaning that pure glucose is above 100 but for the purposes of this discussion we'll use the 100=pure glucose chart).

The idea is here that by following a Low-GI diet you can lose weight (or just be more healthy) by eating fewer simple carbs and get all (or most) of your carbs from Complex healthier carbohydrates.  This staves off diabetes, heart disease, symptoms of PCOS, and of course all the other health benefits we get from eating whole foods (like reduced cancers etc).

When we eat carbohydrates they become sugars in our blood.  The simpler (or easier to process into sugar) the carb, the faster our body's blood sugar spikes and then falls - this results in cravings for MORE carbs and being hungrier.  If we eat the complex carbs (carbs that take longer to make into sugar in our blood) we stay fuller longer, have eaten more nutritious food, and don't crave more junk as soon.  Remember how your mom used to say that "oatmeal sticks to your ribs"...she was right!

Anything without carbohydrates have no effect on your blood sugar.  Therefore meats, cheese, eggs, fish, etc are not rated on the GI list.
Less processed carbs such as fresh veggies, stoneground whole wheat flour, brown rice (not instant), old fashioned oats, pure maple syrup, are lower GI.
Processed carbs and starchy carbs such as baked potatoes, sugar, white flour, white rice are all higher GI.
Some fruits are high-GI but in the amounts that a person actually consumes the sugars are negligible (this is called Glycemic Load - which takes into account the actual carb grams in a likely serving - this is one of the only flaws of the Glycemic Index).

Now - the other thing is that foods don't work alone in your system.  A baked potato has a GI of 85 (very high) which eaten alone will cause your blood sugar to spike.  However, in all likelihood you'll eat this with a steak (or some other meat).  Proteins and fats slow the absorption of the carbs into sugars in your blood.  The combination of the steak with the potato will make your meal medium GI instead of high.

If you eat your carbs with a protein you can lower the GI of your carbs - ie) Crackers with Cheese, Toast with Eggs, Apple Slices and Cheese, Pasta with meat sauce.  This doesn't negate your calories and fat in your diet which you still need to mind if you're trying to lose weight but if you are mindful of your balanced diet you will not be as hungry later and eat fewer calories throughout the day.

The GIs of common foods are available in charts all over the internet.  These are a good starting point to have an idea what the GI of your foods are.  Eventually you'll get to a point where you won't need those charts anymore and you'll have a good idea of what the GI of your meal is.

A few surprising things are that 
-Instant rice and Instant oatmeal are way higher in GI than their long-cooking counterparts.  
-Basmati Rice is lower GI than regular white rice
-New potatoes are low GI
-You can have all the veggies you like - EXCEPT corn (which is higher GI - you can tell because it's sweet...not to say you can't have it - do eat corn but maybe not in unlimited quantities like you can of other veggies) and potatoes.
-Beans/Lentils/Peas are FANTASTIC high fibre/low GI "starchy textures" for your meals.
-Steamed and mashed cauliflower is a low-GI alternative to mashed potatoes.
-Dry white wine is lower GI than most other cocktails.  If you must drink alcohol (which is a HIGH GI -pastime) then try drinking dry white wine.
-Citrus fruits and their derivatives (ie) Lemon water etc) will slow the absorption of sugar into your blood. (I always drink lemon water with pasta).

Remember if you're trying to lose weight then you still need to mind your caloric intake as well as your fat and carbs.  


Tips:
In general - the less processed a product is (that is, the closer it is to its natural state) the lower the GI.
Do not rule out any foods altogether, just be mindful of how much of it you're eating and what you're pairing it with.
Keep an eye on the Sugars on the nutrition data label.  Every 4.5g is a whole teaspoon! And remember, natural sugars (like found naturally in fruits, veggies, milk) are better than added sugars. 
In general more fibre = lower GI.  So eat LOTS of fibre in your breads and cereals.  Rule of thumb for 
cereal is more than 5g fibre per serving, less than 5g sugar per serving.

This is just a quick overview of the concept of the glycemic index.  I'm not a scientist so this my not all be 100% scientifically accurate - but you'll get the gist of it by reading this.