Glycemic Index: Do You Really Understand It?

Carbohydrates have taken a major hit over the last few years, with the latest diet craze being to eliminate any form of carbs or you will die a big fat diabetic death. The truth is though, they aren’t so well understood. One of those reasons revolved around the Glycemic Index (GI). I know most of you will be familiar with what it is, it’s splashed around the TV nowadays, it’s on most of your products from the supermarkets, and there is even a GI diet. But what is it, what are its implications for our eating habits, and what does it mean for us fitness freaks?

What is the Glycemic Index?

The Glycemic index is a way of differentiating between different types of carbs. The GI of a food is referring to how the carbohydrates in food break down into your blood sugar. The way carbohydrates break down greatly affects your blood sugar levels. The GI index tells us how fast a food will break down in your body. Every food has a rating from 1-100. If a food has a GI of 100 (which is basically pure glucose) it breaks down very rapidly. A food with a GI rating of 55 or lower (this is considered low) breaks down a lot more slowly in the body.

High GI Vs Low GI

When you see food advertised on TV, it’s normally with a low GI. Why? Well, high GI foods break down rapidly. Which means you get the sugar straight into your blood, and get a big burst of energy. Sounds great, but you all know when you eat some forms of sugar, you get that high feeling, but then you crash after. Another disadvantage of high GI foods is that fact that insulin levels are raised very rapidly. This is OK, and insulin is a very important hormone in the bodies functioning. However, too much insulin production too often can lead to many health problems, including diabetes. Sounds like we should only be eating low GI foods right? Well,

• Low GI means a slower breakdown, which means longer lasting energy.
• Feel fuller for a lot longer, and help avoid snacking and overeating.
• Your energy levels will stay much more steady, rather than a massive spike and a slump caused by High GI foods.

This sounds perfect eh? It is a much better idea to focus on getting lower GI foods into your body, they are generally a lot better for you. However it isn’t that simple. There are a few surprises along the way with the GI. For example, potato crisps have a much lower GI than boiled potatoes. Now this is a gimme, we know what is better for us. Potato crisps have a very high saturated fat and salt content, and are simply not good for your health, regardless of its GI. This is where the GI diet is flawed. There are quite a few foods like this, and check out at the end of this article for GI values of foods.

High GI and Exercise

High GI foods do have their place. A common practice amongst people trying to gain mass/ muscle or recover from a hard session is to combine a high protein meal/ supplement with a high GI food/ drink (Sports Drinks for example) and consume them directly after exercise. Protein is important for muscle mass and recovery. When we do a weights session or a hard exercise session, there is bound to be microscopic muscle damage. Your ultra intelligent body goes about fixing this immediately, in the process of fixing, also adds some nice adaptations from the session, i.e. You get muscle. To do this though, your body needs some protein, generally fairly soon after the session. It has recently been shown that if you combine the protein with some High GI carbohydrate, the muscles find it a lot easier to uptake the protein and will do so more efficiently. In addition to the protein, you actually need the carbohydrate to recover and adapt as well. So High GI does have it’s place, straight after exercise your body is very tolerant to glucose, and you need it, so get some in ya.

It is also useful for athletes during longer endurance events. Curing marathons or events like the Tour De France, the athletes will take in heaps of sports drinks and gels. These are really high GI foods, and will give those athletes a massive and much needed, almost instant burst of energy. Higher GI means more easily accessible for your body, and that is very important during these kinds of events.

A must for athletes energy needs and recovery

Be Smart…

We need to be careful to keep alienating certain foods. First it was fats are bad…totally horrendous for your body. Food manufacturers then went on to cut out every single spec of fat in every single product. This left us with some pretty high sugar foods. A few years later we realised that fats are good for us; in fact, they are essential to our living. Next rolled in the carbohydrate craze. Low Carb everything was splashed all over the place…no one was allowed to be seen eating a piece of bread for fear of being ridiculed. Well, we have learnt, carbs are OK. Sure, they generally have higher energy values, but again, are essential to our bodies functioning, especially those bodies that are exercises frequently.

Now a similar thing is being done to High GI foods. Everything is Low GI…eat Low GI foods. Yeah, it is correct, but the problem is people are being encouraged to look at it in isolation. Low GI will give you longer lasting energy throughout the day, but as I mentioned above there are so many foods that are tricky. Chocolate has a low GI, but it is 30% fat. You can’t be afraid of eating small amounts of high GI foods. Some breads, pasta, rice and potatoes have pretty high GI’s. If you are having some high GI foods, mix them with some low ones (add some beans of peas to your plate), and you will reduce the total impact.

I do think that the GI index is one of the more important things to be understood when dieting, or even simply watching what you eat. Low GI foods like grains, legumes and vegetables are generally better for you. It is very important to watch that you aren’t taking in too many High GI foods, as severe frequent spikes in insulin can lead to many health problems…not too mention you will be feeling pretty fatigued all the time. But we need to be smart about it. The GI is a great tool to use, however just like many others; it can’t be used in isolation. That’s where the Glycemic Load (GL) comes in handy.

The Glycemic Load

The GL gives people the ability to measure both the type and the amount of carbohydrate in food, giving an indication on how it acts on their blood sugar. The GI is great, but it doesn’t take into account the fact that some foods have a lot more carbohydrate in them than others. A good example is pumpkin. It has a GI of 75, which is very high. A typical 80-gram serving of pumpkin (which is just a few pieces) contains 4-grams of carbohydrate.

So to get the GL…you multiply the GI by the amount of Carbohydrate in the serving, and divide it by 100.

(75*4)/100 = 3

That is a very low GL. You would have to eat a truckload of pumpkin for it to have any effect at all on your blood sugar.

So the take home message is…

Don’t use the Glycemic Index in isolation when choosing what you are going to eat! It is a great tool, and a very important one to understand, but be aware of its limitations.

High GI and GL foods do have their place with athletes and people trying to build mass, or simply recover from a hard session. In everyday eating, like any other tool, use the GI smartly. Nothing can be used in isolation. Low GI foods are better for your health. As a general rule you want longer lasting energy, and less spikes in your blood sugar. Both of these factors will help promote better health, but beware, there are lots of tricks out there. If you are going to eat some higher GI foods like potatoes, balance them out with some lower GI foods in the same meal and all will be OK. Check out this site on the Glycemic Index and head to the GI Database section to enter any food and check its value. Or, check out this site on Glycemic Load with the GI and the GL of foods per serving (need to scroll down to get there).