The bagel you had this morning with 40 grams of simple carbohydrates will rapidly spike your glucose response. This will stimulate the rush of insulin to drive glucose into the cells. This reaction is particularly good after exercising when easy digestible carbohydrates (eaten along with protein) allow the muscle building amino acids to repair the working muscles more efficiently. However, when you have the bagel to barely walk around or to sit in front of the computer for hours, the end result is quite different.
The sugar overflow—no doubt you had a bombshell coffee with your bagel—will soon cause a dramatic sugar level drop, which studies show make you more likely to reach for a quick pick me up. Why not a cookie?
It’s this glucose up and down curve that ultimately impairs the insulin response, thus favoring body fat accumulation along with a chronic inflammatory body state. The result: a higher risk of high cholesterol, diabetes, and high blood pressure, among others.
However, not all carbohydrates elicit the same glucose response. What happens if you have 9-whole grain bread instead of a bagel? Will the sugar spike be the same? Chances are not. And this is where the Glycemic Index—created more than 30 years ago to evaluate how the carbohydrates content in a food impacts blood glucose—comes into play.
While a bagel has a GI of over 70, the 9-Grain bread has a GI below 60. According to the blood glucose response, foods with a GI more than 85 are considered high, while a GI between 60-85 is moderate, and below 60 the GI of the food is low. And the lower the GI number, the better. In theory, this means the food does not upset the blood glucose that much.
GI Savvy Reader
If you’ve been following diets for a while, certainly you’ve come across to more than one that relies on the GI to help you melt the extra pounds. But is it that easy? Does simply following a GI diet make the extra weight go away? There are some solid benefits of following a GI diet—if you understand how this number really works.
Studies show that when subjects have a low GI breakfast, they increase satiety and show a tendency of eating less at lunch time. Likewise, a high GI meal has shown to decrease fat oxidation; a low GI index breakfast has the opposite effect and increases fat mobilization, according to a review published in the Journal of Sports and Health Science. Why is this important? When you decrease fat oxidation, it means your body burns less fat because you have a sugar overflow at hand, so it has to work less to get energy. When fat mobilization increases your body needs to tap into its body fat deposits to release needed energy. In other words, you burn more fat.
Similarly, when three popular diets—low fat, very low carbohydrates, and low GI—were compared in terms of weight management after losing weight, the low GI overall showed a more sustainable way of maintaining the dietary habits than the other diets. Likewise, participants who followed the low GI diet experienced a decrease in cortisol (stress hormone), total cholesterol, and triglycerides. (“Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance,” Journal of The American Medical Association.)
The potential downside to a GI diet is that different foods have different GI numbers. A low GI food paired with medium and medium-high GI choices can still make the overall meal a high GI one. For example, what happens when you put together the bagel, cream cheese, and skim latte? How does the GI work then?
Here is a look at the major obstacle you face on a low GI diet, and some tips and strategies on how to better manage your food choices.
You can eat starch: While many diets forbid starches, low GI leaves rooms for a starchy crave. You just need to know that starch exists in two forms: amylose, which is more resistant to digestion, and amylopectin, which has a faster digestion rate. Usually, a starchy food has between 10%-20% of amylose and 80%-90% of amylopectin. However, some starchy carbs have a better ratio. So to slow down the glucose responses eat more barley, quinoa, long grain basmati rice, oats, and bulgur. Also, green is better: don’t wait for fruits and vegetables to ripen: bananas, plantains, mango, etc. The greener they are, the more resistant starch they have, thus the lower the sugar content and blood glucose impact.
Fiber and whole grain are not the same: Fiber-rich food has been provided a better glucose response than non-fiber food. However, a whole grain food does not make it high in fiber right away. While a 100g of bulgur provides 18.3 g of fiber, the same amount of wild rice has just 6.2 g of fiber. Read the fiber content well before you place it in your shopping cart, and don’t get fooled by some “healthy claims” on the package. For instance, do not trust anything that does not say “100% whole grain.” It should contain no grain ingredients other than whole grain.
Cool off: It matters whether a starch is eaten raw or cooked. Raw oats muesli has a higher amylase content, thus a low GI. Likewise, a starch that has been cooked and allowed to cool (think of a potato salad or pasta al dente) has a lower GI than fresh food, explains Julie Miller Jones, PhD, LN, CNS, in the article “Glycemic Index” published in Nutrition Today.
Mexican feast: Lentils, kidney beans, black beans, and other legumes, do not allow penetration of digestive enzymes and therefore break down more slowly, points out Miller.
Freeze and toast: Instant oatmeal sound like a fast means to breakfast, but Miller says instant starches raise the GI response. Any puffing or popping of grains enables the grains to open and to let the amylase to access the starch, increasing the GI response. So avoid this. But if you want to enjoy bread this strategy won’t sabotage your diet effort. Toasting, freezing or defrosting, or toasting following freezing and defrosting all lower the GI number.
Add some fat: Nuts, olive oil, avocado, and even some cheese added to a moderate-high GI food like rice or potato, reduces the GI. “Fat in food lowers the GI because it slows gastric emptying,” adds Miller.
Time matters: A number of factors affect the GI response. For instance, adding some legumes or barley at evening meal decrease the glycemic response at breakfast, says Miller.
Whereas the GI was created to grasp a more scientific approach of the impact of the carbohydrates in the food in the blood glucose response, its guidelines should be taken carefully. If you strictly follow the GI index, you’ll find foods like ice cream with a low GI while oatmeal has a moderate GI.
As with any diet plan—low carb, gluten free, palio diet, etc.—there are some parts that can better manage your eating habits. And don’t forget that the same way that a gluten-free diet does not necessarily means a healthier diet or the best way to lose weight, a GI diet alone is not a miracle solution.