The Glycemic Index Revisited – By Dr Mike Roussell

 


The Glycemic Index Revisited

by Dr. Mike Roussell – 12/03/2010
 Original article on T-Nation HERE

I’m sure that you can appreciate the importance of optimizing your blood sugar levels; not only for the quest of a lean, muscular physique but, as the opening quote illustrates, the pursuit of good health and a longer life.

But considering that walking around with a glucometer and sticking ourselves after every meal just isn’t practical – or polite – a more efficient method of measuring the effect of carbohydrates on blood sugar levels needed to be determined.

Unfortunately, what athletes, bodybuilders, and TNation readers find scientifically relevant usually doesn’t find its place on the National Institute of Health’s “Top 10 Research Programs to Give Funding To” list.

Sometimes though, we get lucky, and while it wasn’t with the NIH, the British Diabetic Association and the Medical Research Council decided in the late 1970s to find out more about the differing effects of carbohydrate-based foods on blood sugar.

Fast forward to 1981, and the Glycemic Index (GI), a method of ranking the effects of different carbohydrate based foods on blood sugar, was born.

The GI of a food is measured in a two-step process. Researchers will give a person 50 grams of pure glucose and then measure their blood glucose levels over the course of several hours. This pure glucose serves as the control, as theoretically, nothing can be digested faster than pure glucose.

Next, researchers give the same person 50 grams of the food in question (like carrots, rice cakes, or black beans), and measure their blood glucose levels for several hours afterwards. As the diagram on the right and the following technical definition of the GI shows, the blood sugar responses for the two foods are then compared.

One key component to how the GI is measured has to do with amount. The amount of food used is always the same, 50 grams. As a result, the GI only takes into account the type of carbohydrate and not the amount. This is a point of criticism that many GI critics often bring up; for example, how practical is the GI when 50 grams of carbs from rice can be ingested with ease while 50 grams from carrots would require Bugs Bunny-like dedication?

The Glycemic Load

To make the GI more real world applicable – as no one eats food in 50-gram increments – scientists came up with the Glycemic Load (GL). The GL is a carbohydrate/blood sugar rating that accounts for both type and amount of carbohydrate.

It’s defined by this equation:

Here’s an example of how the GL works versus the GI:

Food Standard Serving Size Glycemic Index Glycemic Load
Jasmine rice 150g 99 42
Carrots 80g 47 3
Apple 120g 34 5

Traditionally, the much-maligned carrot is vilified by GI disciples because they have a higher GI than most vegetables (one study found the GI of carrots to be 90 but these findings were never replicated), but as you can see the average GI for carrots is only 47 – which actually makes carrots a low GI food – and when you take into account the amount most non-hares would normally eat, the GL for carrots is really very low.

The GI is a property of a food, just like the amount of protein or fat in a food, while the GL refers to the composition (type of carbohydrate) and size of your meal (amount of carbohydrate).

Dr. Wolever, an Oxford trained physician, nutrition PhD, and world leading expert on the Glycemic Index, hammered this point home repeatedly in a seminar I attended recently. This is an important designation, as it makes a food’s GI rating applicable across different populations.

The Insulin Index

You might have heard about a study published over a decade ago talking about the Insulin index. Like the GL, the idea behind the Insulin Index is that scientists wanted to quantify the effects that different foods had on insulin levels.

But one problem with the Insulin Index is that the insulin response can vary tremendously between individuals, thereby requiring a lot of extra data on the effects of different foods in a variety of populations to have a standardized version of the Insulin Index.

To further complicate matters, the Insulin index concept never really took off in the scientific community – at the time of writing this article, there were 22 times more scientific papers in PUBMED about the GI compared to the Insulin Index.

Now that we’ve established the various indexes, let’s see how you can best apply them to your physique pursuits. Here are two important points:

I always stress this point with clients when we discuss carbohydrates, blood sugar, and the Glycemic Index. Generally (and practically) speaking, foods with a low GI will also have a low GL.

Green leafy vegetables have a low GI, and while you can eat a large volume of these foods, the actual gram amount of carbohydrate that you’re consuming will also be low (making the GL low as well), while foods with a higher GI are usually more carbohydrate dense (meaning that if you eat a large volume of these foods, you’ll also be eating a lot of carbohydrates).

Long story short: Meals with low glycemic carbs will naturally have a lower GL and meals with higher glycemic carbs will naturally have a higher GL. Why make it more complicated than it has to be?

Another point of criticism regarding the GI is consistency. While the measuring of a food’s GI is supposed to be a standardized procedure, different labs have calculated different GI’s for the same food. While this might sound like a problem, it really isn’t. Why?

As you can see by the chart below, when using the GI to categorize foods, three main categories are used: High, medium, and low.

High GI Foods Medium GI Foods Low GI Foods
Shredded Wheat Apricots Green Vegetables
Bagel Long Grain Rice Nuts
White or Whole Wheat Bread Pita bread Apples
Couscous Raisins Barley
Cornflakes Brown Rice Oranges
Rice Cakes Pineapple Strawberries
Pancakes     Corn Tortilla
      Hummus
    Lentils
    Grapefruit

If you follow my recommendations and use the GI as a tool to improve your carbohydrate choices, high versus low GI is what really matter. When researchers combined discrepancies found between laboratories and published studies, low GI foods were always low GI foods and high GI foods were always high GI foods.

Jasmine rice and rice cakes don’t suddenly become low GI foods simply because two labs can’t agree on a score.

The Glycemic Index of Foods Can Change

Remember when I mentioned above that the GI of a food was a property of the food? After reading that, you might’ve thought that means that the GI rating of a food always stays the same. Unfortunately, that’s not always the case due to some interesting food science – and more recently, the unrelenting efforts of food companies to get ‘whole grains’ into our diets.

There are three common ways that the GI of a food can change: processing, ripeness, and cooking. Let’s take a look at how cooking can influence the GI.

The Potato Story

This is where it gets really cool. Let’s say you take a potato; prepare and eat it two different ways and it’ll have two different GI ratings.

Raw potatoes, cooked potatoes, and potatoes that are cooked and then cooled all have different GI ratings due to the potato’s unique starch make-up. Certain types of potatoes, like red potatoes, contain high levels of amylose. When cooked, amylose is released, mixes with water molecules and forms a gel like substance. By letting the potatoes cool, you’re giving the gel a chance to solidify into a state that’s more resistant to digestion. If you eat it while it’s still hot, the gel is still gelling, and it will get digested faster.

Lest you think this is the spud-inspired version of splitting hairs, think again: according to one researcher I talked, to the difference between eating a warm potato versus waiting for it to cool and then eating it can be a GI rating of 75 versus 40!

Who would have thought that potato salad could be better for you than a steaming baked potato?

Here’s a muscled-up version of potato salad for you to try:

  • 3 medium red potatoes
  • 1/2-cup olive oil mayonnaise
  • 5 chives, minced
  • 2 strips turkey bacon (not the processed Jennie-0 stuff that looks like play-dough pressed into a bacon form – try Applegate Farms)
  • 1/2 medium onion, diced
  • 1 stalk celery, diced
  • 1 Tbsp yellow mustard


How to Prepare:

Place the potatoes in a medium-sized pot with boiling water. Cook for ~15 minutes, until the potatoes are fork tender. While the potatoes are cooking, cook the turkey bacon in a nonstick frying pan over medium heat. Once the potatoes are cooked, remove them from the pot and let cool.

Next, dice up the turkey bacon and place in a bowl with the mayonnaise, chives, onion, celery, and yellow mustard. When the potatoes have cooled, cut them up into 1-inch cubes. Add to the bowl and mix thoroughly. Add salt, pepper, and Frank’s Red Hot to your desired taste. Makes 2 servings (see nutrition facts below).

Enjoy this with a roasted chicken breast or grilled flank steak for a great post training meal.

Protein and Carbohydrate Affects on Glycemic Index & Glucose Response

Another criticism of the reliability and effectiveness of the GI is that it ranks foods by themselves, when in reality, when we eat carbohydrate-based foods, we eat them together with protein and fats.

Another factoid I frequently hear bandied about is that “adding protein and fats to a meal reduces the GI of rice/potato/Pop Tarts/etc.”

However, as stated earlier, one of the important points about the GI rating is that it’s a property of the food, so adding fat and protein to a meal containing white rice for example doesn’t change the GI of rice, it only will reduce the rise in blood sugar…or will it?

In 2006, Dr. Wolever published a study that was the first to systematically examine the ‘mixed meal’ question. In this study, participants received shakes containing glucose (50 grams), protein (0, 5, 10, or 30 grams), and fat (0, 5, 10, or 30 grams).

The researchers found that gram-for-gram, protein had almost a three times greater effect than fat at reducing glucose response to the meal. They also found that the effect of protein was linear across the protein dosages (0 grams to 30 grams), so that the more protein that was in the shake, the greater the reduction in glucose response.

Dr. Wolever cautioned against taking these findings out of context, as the study used liquid shakes and not whole food meals. But as a TNtaion reader who probably has a second pantry dedicated to tubs of Metabolic Drive, this research is especially relevant to you.

To further explore the ‘mixed meal’ question, Dr. Wolever ran another study, this time using whole food meals. The meals contained 0-18 grams of fat and/or protein and 16-79 grams of carbohydrates (with GI’s ranging between 35-100).

They found very different results than the previous smoothie study: when using whole foods, the protein and fat content of the meals had a negligible effect on glucose levels. The total carbohydrate content of the meal and the GI of the foods in the meal were able to predict glucose response with almost 90% accuracy.

While they might have found different effects at higher protein dosages, when these two studies are taken together the message is pretty clear: if you’re having a shake, then adding protein to that shake is a good way of controlling your blood sugar response.

If you’re having a whole food meal, then eating low glycemic carbs and reducing your total carb intake (which can be done by eating low glycemic carbs) is the best way to control your blood sugar response.

Glycemic Index, Nutrition Timing, and Your Diet

What’s the best way to use glycemic index in your diet? You can use the glycemic index to optimize the nutrient timing of your diet.

Phase AM Workout/Post Workout PM
Hypertrophy Phase High + Medium GI carbs Mainly High GI carbs Low & Medium GI carbs
Maintenance Phase Low + Medium GI carbs Mainly High GI carbs Low GI Carbs
Fat Loss Phase Low GI carbs Mainly High GI carbs Low GI carbs

The Glycemic Index Wrap Up 

Virgin Coconut Oil

 

Virgin Coconut Oil

Coconuts for many people are what we have in the occasional curry or cocktail, but for millions of people covering many countries, religions and cultures, the humble coconut is a source of food, medicine and / or revenue. There are may websites claiming to sell the purest grade virgin coconut oil that will help to loose fat, fight infections, ease eczema, soften your hair, improve your skin and much more. 

   I have personally never had the pleasure of using pure Virgin (unrefined) Coconut oil.  When I first read about coconut oil I went out and bought a tub only to find it was refined and didn’t posses the fine health building properties that the unrefined oil has. I will get around to purchasing some good quality Virgin oil and I will report back with my results.  Until then, I can tell you that Coconut oil does contain lauric acid, which is known for being anti-viral, antibacterial and anti-fungal. Lauric acid is a MCT (medium chain triglycerides) and is used fast and effectively by the body and does not seem to raise cholesterol.

  Do some reading and you will find out for yourself how this once shunned oil has MAY pretty impressive health benefits.   If you have had any personal experience using Virgin Coconut  Oil, good OR bad,  that you would like to share with other people, please email me at and let me know.  Until then, below is some information and some links for you to look at and enjoy.

Coconut

(Cocos nucifera)

 

Copied from the coconut research center, you can read here

 

The Tree of Life

The scientific name for coconut is Cocos nucifera. Early Spanish explorers called it coco, which means “monkey face” because the three indentations (eyes) on the hairy nut resembles the head and face of a monkey. Nucifera means “nut-bearing.”

The coconut provides a nutritious source of meat, juice, milk, and oil that has fed and nourished populations around the world for generations. On many islands coconut is a staple in the diet and provides the majority of the food eaten. Nearly one third of the world’s population depends on coconut to some degree for their food and their economy. Among these cultures the coconut has a long and respected history.

Coconut is highly nutritious and rich in fiber, vitamins, and minerals. It is classified as a “functional food” because it provides many health benefits beyond its nutritional content. Coconut oil is of special interest because it possesses healing properties far beyond that of any other dietary oil and is extensively used in traditional medicine among Asian and Pacific populations. Pacific Islanders consider coconut oil to be the cure for all illness. The coconut palm is so highly valued by them as both a source of food and medicine that it is called “The Tree of Life.” Only recently has modern medical science unlocked the secrets to coconut’s amazing healing powers.

Coconut In Traditional Medicine

People from many diverse cultures, languages, religions, and races scattered around the globe have revered the coconut as a valuable source of both food and medicine. Wherever the coconut palm grows the people have learned of its importance as a effective medicine. For thousands of years coconut products have held a respected and valuable place in local folk medicine.

In traditional medicine around the world coconut is used to treat a wide variety of health problems including the following: abscesses, asthma, baldness, bronchitis, bruises, burns, colds, constipation, cough, dropsy, dysentery, earache, fever, flu, gingivitis, gonorrhea, irregular or painful menstruation, jaundice, kidney stones, lice, malnutrition, nausea, rash, scabies, scurvy, skin infections, sore throat, swelling, syphilis, toothache, tuberculosis, tumors, typhoid, ulcers, upset stomach, weakness, and wounds.

Coconut In Modern Medicine

Modern medical science is now confirming the use of coconut in treating many of the above conditions. Published studies in medical journals show that coconut, in one form or another, may provide a wide range of health benefits. Some of these are summarized below: 

  • Kills viruses that cause influenza, herpes, measles, hepatitis C, SARS, AIDS, and other illnesses.
  • Kills bacteria that cause ulcers, throat infections, urinary tract infections, gum disease and cavities, pneumonia, and gonorrhea, and other diseases.
  • Kills fungi and yeasts that cause candidiasis, ringworm, athlete’s foot, thrush, diaper rash, and other infections.
  • Expels or kills tapeworms, lice, giardia, and other parasites.
  • Provides a nutritional source of quick energy.
  • Boosts energy and endurance, enhancing physical and athletic performance.
  • Improves digestion and absorption of other nutrients including vitamins, minerals, and amino acids.
  • Improves insulin secretion and utilization of blood glucose.
  • Relieves stress on pancreas and enzyme systems of the body.
  • Reduces symptoms associated with pancreatitis.
  • Helps relieve symptoms and reduce health risks associated with diabetes.
  • Reduces problems associated with malabsorption syndrome and cystic fibrosis.
  • Improves calcium and magnesium absorption and supports the development of strong bones and teeth.
  • Helps protect against osteoporosis.
  • Helps relieve symptoms associated with gallbladder disease.
  • Relieves symptoms associated with Crohn’s disease, ulcerative colitis, and stomach ulcers.
  • Improves digestion and bowel function.
  • Relieves pain and irritation caused by hemorrhoids.
  • Reduces inflammation.
  • Supports tissue healing and repair.
  • Supports and aids immune system function.
  • Helps protect the body from breast, colon, and other cancers.
  • Is heart healthy; improves cholesterol ratio reducing risk of heart disease.
  • Protects arteries from injury that causes atherosclerosis and thus protects against heart disease.
  • Helps prevent periodontal disease and tooth decay.
  • Functions as a protective antioxidant.
  • Helps to protect the body from harmful free radicals that promote premature aging and degenerative disease.
  • Does not deplete the body’s antioxidant reserves like other oils do.
  • Improves utilization of essential fatty acids and protects them from oxidation.
  • Helps relieve symptoms associated with chronic fatigue syndrome.
  • Relieves symptoms associated with benign prostatic hyperplasia (prostate enlargement).
  • Reduces epileptic seizures.
  • Helps protect against kidney disease and bladder infections.
  • Dissolves kidney stones.
  • Helps prevent liver disease.
  • Is lower in calories than all other fats.
  • Supports thyroid function.
  • Promotes loss of excess weight by increasing metabolic rate.
  • Is utilized by the body to produce energy in preference to being stored as body fat like other dietary fats.
  • Helps prevent obesity and overweight problems.
  • Applied topically helps to form a chemical barrier on the skin to ward of infection.
  • Reduces symptoms associated the psoriasis, eczema, and dermatitis.
  • Supports the natural chemical balance of the skin.
  • Softens skin and helps relieve dryness and flaking.

  • Prevents wrinkles, sagging skin, and age spots.

  • Promotes healthy looking hair and complexion.

  • Provides protection form damaging effects of ultraviolet radiation form the sun.

  • Helps control dandruff.

  • Does not form harmful by-products when heated to normal cooking temperature like other vegetable oils do.

  • Has no harmful or discomforting side effects.

  • Is completely non-toxic to humans.

See Research to read some of the published studies regarding the above mentioned uses of coconut products.

Coconut Oil

While coconut possesses many health benefits due to its fiber and nutritional content, it’s the oil that makes it a truly remarkable food and medicine.

Once mistakenly believed to be unhealthy because of its high saturated fat content, it is now known that the fat in coconut oil is a unique and different from most all other fats and possesses many health giving properties. It is now gaining long overdue recognition as a nutritious health food.

Coconut oil has been described as “the healthiest oil on earth.” That’s quite a remarkable statement. What makes coconut oil so good? What makes it different from all other oils, especially other saturated fats?

The difference is in the fat molecule. All fats and oils are composed of molecules called fatty acids. There are two methods of classifying fatty acids. The first you are probably familiar with, is based on saturation. You have saturated fats, monounsaturated fats, and polyunsaturated fats. Another system of classification is based on molecular size or length of the carbon chain within each fatty acid. Fatty acids consist of long chains of carbon atoms with hydrogen atoms attached. In this system you have short-chain fatty acids (SCFA), medium-chain fatty acids (MCFA), and long-chain fatty acids (LCFA). Coconut oil is composed predominately of medium-chain fatty acids (MCFA), also known as medium-chain triglycerides (MCT).

The vast majority of fats and oils in our diets, whether they are saturated or unsaturated or come from animals or plants, are composed of long-chain fatty acids (LCFA). Some 98 to 100% of all the fatty acids you consume are LCFA.

The size of the fatty acid is extremely important. Why? Because our bodies respond to and metabolize each fatty acid differently depending on its size. So the physiological effects of MCFA in coconut oil are distinctly different from those of LCFA more commonly found in our foods. The saturated fatty acids in coconut oil are predominately medium-chain fatty acids. Both the saturated and unsaturated fat found in meat, milk, eggs, and plants (including most all vegetable oils) are composed of LCFA.

MCFA are very different from LCFA. They do not have a negative effect on cholesterol and help to protect against heart disease. MCFA help to lower the risk of both atherosclerosis and heart disease. It is primarily due to the MCFA in coconut oil that makes it so special and so beneficial.

There are only a very few good dietary sources of MCFA. By far the best sources are from coconut and palm kernel oils.

Copyright © 2004 Coconut Research Center

This website is for educational purposes only. The information supplied here comes from a variety of sources and authors and not every statement made has been evaluated by the FDA. This information is not intended to diagnose, treat, cure or prevent any disease.

 More Links with great information about the wonders of Coconut Oil.

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