Glycemic Index (GI)

I have referred to the glycemic index and to "low GI" foods several times in this blog. A few words about that concept. Glycemic index is a way of rating the speed of absorption of carbohydrates. So, e.g. pizza has a glycemic index of 80 (high, see below) and peanuts have a GI of 13 (low). This means that pizza raises your insulin levels much more than peanuts do - and high insulin levels are what makes us gain weight (or hold onto fat).

Insulin is a hormone. When our insulin levels are high, we accumulate fat in our body. When our insulin level is low, we liberate fat from our existing fat tissue and burn it for fuel - this is what low-carb dieting is based on, because only carbs elevate our levels of insulin. The GI of e.g. meat or cheese is zero, meaning that it does not elevate our insulin level at all (pictured is one of my fave snacks: Mini BabyBels - yummy!)

The worst carbs (from a dieters point of view) are: beer, fruit juices (even natural, unsweetened ones), sodas with sugar in them (diet sodas are much better and ones without caffeine are even better, since caffeine also raises insulin levels). And obviously white sugar is also one of the worst offenders. Whenever you can, you should try to eliminate it completely. You can replace it with a sugar substitute when necessary.

So this is really how we gain weight: carbohydrates -> elevate insulin levels -> make us gain weight

So if we eliminate carbs, we will lose weight (or not gain any, if we are already at our ideal weight). However, most people may not want to eliminate carbs altogether and that's where the GI comes into play. It rates carbs on how "good" they are, meaning how much they raise our level of insulin.

High GI - 70 or more
Medium GI - 56 to 69
Low GI - 55 or less

There are many websites that provide a GI database, i.e. that list the GI of thousands of foods. Here is one example:
http://www.glycemicindex.com/

I found interesting facts there:

- the GI of "rich" (I am assumign this means full fat) ice-cream is 38, meaning it's low!!
- the GI of an apple is 40 - so an apple is as fattening as ice-cream! (obviously an apple is a healthier choice - my point is mainly that if you must indulge in something "naughty", try to make it low GI in any case).
- the GI of a pineapple is 59, so pretty high
- white rice (the Japanese kind) has a GI of 86 (i.e. it's more fattening than pizza)
- Nutella chocolate hazelnut spread has a GI of only 30 (I think I'll buy some!)
- peanut M&Ms have a GI of 33 (yum!)
- bread with peanut butter has a GI of 51-67 (too high for me, won't be eating any)
- peanuts have a GI of 7 to 23, so quite low - it's OK to eat e.g. salted peanuts as a snack
- mixed nuts & raisins: GI 21
- foods containing little or no carbs are not listed, since their GI is zero. Such foods include: all meat (check in the case of processed meats!), all fish and seafood, avocado, wine (!!), spirits, most vegetables (the best ones being leafy green vegetables). Some good options: butter, mayonnaise, cream (the full-fat kind), bacon, all oils, coconut, all nuts, peanut butter (but note that you should not have bread with it....).

One more thing to note (which is new info for me) is that now there is a new concept in addition to GI, referred to as GL - glycemic load. It takes into account also the typical quantity of the food item consumed.

Here is a quote from Wikipedia:
"The usefulness of glycemic load is based on the idea that a high glycemic index food consumed in small quantities would give the same effect as larger quantities of a low glycemic index food on blood sugar. Glycemic Load is the product of the Glycemic Index and the grams of available carbohydrate (GL = GI × available Carb grams). For example, white rice has a somewhat high GI, so eating 50g of white rice at one sitting would give a particular glucose curve in the blood, while 25g would give the same curve but half the height. Since the peak height is probably the most important parameter for diabetes control, multiplying the amount of carbohydrates in a food serving by the glycemic index gives an idea of how much effect an actual portion of food has on blood sugar level."

So if I understand correctly, the important figure we should be looking at is the GL. But of course looking at the absolute GI is OK also - just make sure that you keep quantities of high GI foods low!