Does the glycemic index matter?

[shadowbox]The Glycemic Index ranks foods on how they affect the blood glucose levels. It measures the amount of increase in your blood glucose levels two to three hours after eating.[/shadowbox]

The Glycemic Index shows how quickly a single food will turn into blood glucose on a scale of 100. Pure glucose is given a value of 100.

Question:

Marc – I just read a post from <removed so I do not pass traffic to this guy> that microwaving a sweet potato raises the glycemix index to that of a fruit rollup!  I don’t want to be eating candy when I’m prepping for a show.  Should I be worried about the GI of foods?  FYI.. I’m not diabetic or anything.

Answer:

Yeah, I saw the same post.  It linked to an abstract study.  I guess these days if you read an abstract (the conclusion) that only study then sets the record going forward.  It is just another example of taking 1 study out of context, making a killer graphic to share on social media and sharing it with your massive fanbase.  This is how myths get started.  Frankly, it’s best never to take advice from someone who shares such clickbait and at the bottom, promotes their $X.XX a month membership site.

The Glycemic Index was created with the diabetic in mind.

You see, insulin spikes can be deadly to the diabetic. This fueled the need to develop a chart showing the insulin effects of certain foods. Clearly diabetics don’t want large spikes in insulin when preparing meals.

Before 1981, scientists believed that avoiding table sugar was the goal as it raised the glucose levels quickly. Current studies show that some foods actually have a higher blood glucose level than table sugars!

While it’s still a good idea to avoid empty sugar calories there’s many other foods that can spike the blood glucose levels.

Clearly not all foods are the same and they don’t have the same insulin effects on the body. Today it’s still favored to have a diet high in carbs and fibers and to avoid sugars.

Now get this: A baked potato ranks higher on the Glycemic Index than table sugar at 64! While some pastas rank lower than a baked potato and even table sugars.

But that’s not all…

You can see it’s value to a diabetic but using the Glycemic Index as a primary tool for choosing food can create problems.

First…

As you know, the Glycemix Index ranks how a single food breaks down in your body and is convered to blood glucose after eating. But if you follow the rules of performance nutrition, you should be eating a ‘complete’ meal:

  • that consists of a lean protein
  • a starchy carbohydrate
  • and a fibrous carbohydrate

Not a single food by itself.

This changes the Glycemix Index of that meal!

Second…

When you consume proteins with carbohydrates, it can greatly lower the blood glucose effects of that food. A baked potato’s score 85 on the Glycemic Index when combined with a protein is much lower.

Third…

There are flaws of the Glycemic Index like:

Limited data. Only about 5% of the foods are listed in the Glycemic Index. And there is a very limited number of researchers that currently do testing.

The numbers on the Glycemix Index are an average of the responses of groups of people. This explains the variation in some charts. The numbers listed are not exact values.

A wide variation of in the actual Glycemic Index measurements. For example, a baked Russet potatoes have been tested with a Glycemic Index as low as 56 and as high as 111!

Food preparation methods like microwaving, grinding, frying, baking, etc. There’s even differences in the GI when boiling pasta for 10 minutes or 15 minutes.

Food combinations can affect the Glycemic Index of a listed food. While the Glycemic Index is based on single foods, we often consume foods in combinations. This can affect the overall Glycemic Index of that meal. Figuring out the precise Glycemic Index of foods after being mixed is less accurate.

Individual differences in a response to a food on the Glycemic Index. People simply have different blood glucose responses. Without monitoring each person’s actual blood glucose levels, results can and often will vary.

Reliance on the Glycemic Index can lead to over eating. If you only rely on the Glycemic Index to pick and choose foods you can end up consuming too many fats and excess calories.

In any event, the Glycemic Index is useful to people with certain dietary needs. But it’s service to the bodybuilder is vague. There’s no way that refined pasta is better for you than nature’s own potato.

Basing your choices only on the Glycemic Index can lead to over consumption of high calorie foods. And with the limited data and varied testing results, your own reactions to a particular food may vary greatly.

Needless to say…

If you follow the rules of performance nutrition and eat complete meals your goals will be much better served.

The Glycemic Index’s relevance to health and nutrition is controversial.  For example, the AHA, American Diabetes Association, and American Dietetic Association do not endorse using the GI for disease prevention and treatment (Ludwig and Eckel 2002). Pi-Sunyer (2002) concluded that there is insufficient evidence to justify basing public health recommendations on the GI. In fact, the Dietary Guidelines for Americans 2010 stated that there is strong evidence that the GI is not associated with body weight and does not lead to greater weight loss or better weight maintenance.

Resources for More Information on Glycemic Index:

  1. http://www.glycemicindex.com/
  2. http://en.wikipedia.org/wiki/Glycemic_index
  3. http://nutritiondata.self.com/topics/glycemic-index
  4. http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm
  5. http://www.diabetes.org/food-and-fitness/food/planning-meals/glycemic-index-and-diabetes.html
  6. http://www.mayoclinic.com/health/glycemic-index-diet/MY00770
  7. http://www.mendosa.com/gilists.htm
  8. http://diabetes.webmd.com/glycemic-index-good-versus-bad-carbs
  9. http://whfoods.org/genpage.php?tname=faq&dbid=32
  10. http://lpi.oregonstate.edu/infocenter/foods/grains/gigl.html
  11. http://ajcn.nutrition.org/content/76/1/5/T1.expansion
About the Author
Glad to meet you! I'm Marc David, the only person behind JustAskMarc. I'm a podcast enthusiast, ISSA certified trainer and a lifelong bodybuilder. Follow me @marc_david and at my FB page.

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