Can Glycemic Index Impact Fat Loss through the Flexible Dieting Approach?


Glycemic index (GI) – do we really need to pay attention to this in our diet plan?  Some research that I found says there is no long-term effects to fat loss while others say there are some positive effects. However, when it comes down to our flexible dieting program, it’s all about balance control which then should even out our blood glucose levels in the long run!  Here’s some background on what GI is and if we should be concerned with it.  Remember, if you are in doubt with ANY nutrition plan, always consult a medical professional first, especially if one has diabetes!  Happy reading – be sure to click on the articles that I’ve found to help educate yourself about the process!

What is glycemic index (GI)?

According to the American Diabetes Association (ADA), GI measures how foods that contain carbohydrates (CHO) raise blood glucose levels.  Blood glucose, or blood sugar, is primarily the source of energy for our body’s cells.  Blood glucose is transported from the liver into the blood stream via the insulin hormone that is found in the pancreas.  Normal levels of blood glucose should range from 3.9 to 5.5 mmol/L, when in a fasted state; average levels are about 5.5 mmol/L in individuals without diabetes.

Are there different levels of GI that I should consider?

Yes.  Glycemic index has different rankings, a scale of 0-100:  low (55 or less), medium (56-75),  and high (76 or more).  High GI foods typically raise the blood glucose levels faster, while low GI foods raise the blood glucose levels slower.  When we prep our food and plan ahead, we want to strive for a well-balanced meal containing high, medium, and low GI foods in order to prevent fast spikes in our blood sugar levels, especially if one has diabetes (again, consult a medial professional for assistance on controlling your diabetes if you are unable through proper diet).

Here’s some examples of each rank of GI foods:

Low GI (55 or less) = rolled/steal-cut oatmeal, sweet potatoes/yams, most fruits, and non-starchy vegetables

Medium GI (56-75):  whole wheat bread, quick oats, and brown rice

High GI (76-100):  white bread, bagels, russet potatoes, and pineapples

Click here, for more information regarding GI.


What can effect the GI of foods?

The ADA poses some great considerations when choosing the right foods with specific GIs associated with them.  Some aspects to consider are:

  • Physical forms of the food
  • Food combination during consumption (including fats/proteins within each meal)
  • Processing of the food
  • Ripeness and storage time of the food
  • Cooking method of the food
  • Soluble fiber content of the food

Click this article for more information on GI application/effects.

Is there anything else I should consider with GI?

Yes.  Glycemic load (GL) to be exact.  Glycemic load is calculated on the portion size and the GI of the food eaten; it measures the impact of ingested CHO on the body AND blood glucose levels.  It also has a scale to base it’s content off of ranging from 0 to greater than 20.  To calculate GL, one must take the GI multiplied by the portion size and then divide that number by 100.  Typically, foods that have less CHO content (i.e. watermelon) with a smaller serving size of CHO will yield lower GL levels; thus, one could consume more of that particular food when compared to other higher process foods such as cookies or breads, which have a higher CHO content.

Examples of each rank of GL foods:

  • Low GL (10 or less) = legumes, lentils, cashews/peanuts, and milk
  • Medium GL (11-19) = oatmeal, whole wheat pasta, and sweet potatoes
  • High GL (20 or more) = candy, high-sugar soft drinks, pizza, and white pasta/rice

Check out this article here regarding GL content.

So can I still loss body fat by utilizing the GI/GL?

Yes.  It is essentially a way of “counting CHO” within each food you eat.  Think of GL as foods containing fiber – we want to make sure these foods are well-balanced in our nutrition plan; however, we still want to make room for foods with varied GIs too, such as cookies, pop tarts, and ice cream (my favorite)!

Upon research by Tufts University Health Science Campus, this team of researchers found that neither GI nor GL is the way to go when monitoring long-term fat loss and blood glucose levels.  Since GI can vary so much based on the type of food, shelf life, and even the way it’s cooked, eating the same foods day by day can have a 20% different effect on the body’s blood glucose levels (food for thought)!  Therefore, these researchers found that GI/GL is an unreliable resource to solely rely on when monitoring blood glucose levels and fat loss.

Another article, Kirpitch et al., points out that a nutrition plan emphasizing a low-GI and high protein approach can help aid in increased fat loss AND a decrease in blood glucose levels.  In turn, this can possibly help those with diabetes to discontinue oral medication for homeostasis of blood glucose monitoring (always consult your doctor first when thinking of changing medications).  As noted, Kirpitch et al. also mentions that decreasing overall caloric intake levels will help increase fat loss, BUT fails to mention proper balance level suggestions of macronutrient intake levels to be exact.

Concluding thoughts

Per Kirpitch et al., “The most helpful message for patients is to not focus on the numerical GI or GL values of foods, but rather to think about the overall glycemic impact of the food.  Keep in mind that many foods that are encouraged in a healthy meal plan such as broccoli, spinach, lettuce, and cucumbers have not been evaluated for a GI level.  Thus, it is most helpful to give patients general guidance to limit their intake of foods with a higher GI such as white, highly processed breads and grains and replace these with lower-GI foods such as most fruits and vegetables, dairy products, beans and legumes, and whole grains”.

To reiterate, my aunt always says “garbage in – garbage out”.  So how do you know if it’s working? How do I track my food intake levels?  Where do I even start with this process?  First, always consult a medical professional about nutrition planning especially if you have diabetes (or any other co-morbidities) – plan your scheduled visits with him/her accordingly and always be sure to take your medications as prescribed.  Then use a flexible dieting approach to create good eating habits/patterns without keeping certain foods off limitis – just be mindful when consuming processed foods such as cookies, cake, and cornflakes!  Then, head on over to the BullsEye Nutrition page and sign up with your coach today to help guide you along the way!  Happy eating #teambullseyenutrition

References (in no specific order):

  6. http://Tufts University, Health Sciences Campus. (2016, September 7). High variability suggests glycemic index is unreliable indicator of blood sugar response. ScienceDaily. Retrieved November 1, 2016 from

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