Getting maximum results from weight training and building muscle depends heavily on how you manage your body’s secretion of the hormone insulin. The presence of insulin is critical to creating and maintaining the body’s natural anabolic drive(1). The anabolic drive is the synergistic interaction of anabolic hormones, growth factors, and nutrients that control muscle growth. No one has figured out exactly how it all works. However, insulin is a key component, and it influences every muscle-building pathway in our physiology.
Most athletes are aware that insulin facilitates transportation of nutrients into cells. However, not many know that insulin also works in tandem with growth hormone secretion and interacts synergistically with the thyroid hormone T4 within the liver to produce the potent but short-lived muscle growth factors, particularly Insulin-like Growth Factor-1 (2). This is the growth factor that builds big muscle.
Insulin-like Growth Factor-1 (IGF-1) requires lots of insulin to work and prolong its active life (1,3). Some research demonstrates that insulin enhances the entire anabolic hormonal profile after intense exercise (5). Maintaining this anabolic drive during the day, – every day – is dependent upon steady-state insulin levels (3,4). Therefore, your food choices every day completely and utterly govern your fat burning, muscle-building results.
Poor food choices after training or a haphazard approach to your diet create surging and plummeting blood sugar and insulin levels. This short circuits your anabolic drive and stops your muscle-building efforts dead in their tracks.
Insulin is secreted into the bloodstream in response to the foods we eat. Foods high in carbohydrates have the greatest impact on blood sugar and insulin (6). Therefore, your carbohydrate selection during the day and night can make or break your results.
So, what’s a carbohydrate?
The simplest form of carbohydrate is what is known as a single sugar molecule called glucose. To be utilized as energy in every cell in the body, all carbohydrates eventually end up as glucose. As we know, man has also done a good job of isolating glucose and adding it to many packaged foods. Chemically, glucose is known as a monosaccharide (mono= one, saccharide = sweet).
If two glucose molecules are joined together, it is called a di-saccharide. Common table sugar is a di-saccharide called sucrose. Other common di-saccharides are maltose and lactose. Just to confuse you, fructose (the common sugar in fruit) is a slightly different single sugar molecule than glucose.
All carbohydrates are simply chains of the glucose molecule linked together (polysaccharides). In food, these polysaccharides are called starches. In muscle, these stored polysaccharides are called glycogen.
Dietary fibers are complex structures that contain many types of sugar molecules, but they are different to starches and sugars. They cannot be digested. Humans do not possess the digestive enzymes that break apart the bonds that hold these sugar molecules together. Therefore, they pass entirely your system undigested.
What’s wrong with today’s carbohydrates?
We are the product of industrialization. Inventions ranging from Jethro Tull’s seed drill (in 1709) to the high-speed steel roller mills for milling cereals (19th century) are all advances in food processing to give food a longer shelf life (6). Although foods are based on our staple cereals such as wheat, oats, corn and rice, the original grain has been ground down to produce a powder-like flour, minuscule in particle size.
Food chemists know that the finer (smaller) the particle size flour, the more fluffy and delicious the food will be(7). It also extends shelf-life of the end product enormously. However, the constant refinement of the whole-food over recent centuries has resulted in dire consequences to our health that we are only now just becoming aware of. The incidence of obesity, diabetes and cardiovascular disease are at all time, record-highs in human history. This is directly linked to over-consumption of refined foods.
Highly refined foods create poor insulin management. They are too rapidly absorbed and flood the bloodstream with sugar (glucose). The pancreas secretes insulin into the blood in an attempt to eliminate this flood of glucose. Over a gradual period, cells become resistant to this constant bombardment of high insulin that refined foods induce.
These high insulin levels desensitize our cells (particularly in muscle), and the pancreas has to work harder to secrete more and more insulin, all to complete the job of nutrient transport into cells. After years of this physiological abuse, the pancreas gives up and fails to produce much insulin at all.
When this occurs, doctors politely term the condition “adult-onset diabetes.” While some poor folks are genetically predisposed to developing this condition, adult-onset diabetes, in most cases, is entirely preventable.
In fact, developing adult-onset diabetes, in most cases, is more like a trophy that says “congratulations, through years of dietary abuse, you have successfully managed to wear out your pancreas.” Some trophy, huh? It’s one disease that has fatal implications for your health, and once you have it, you carry it for the rest of your days. Which, by the way, are usually reduced in number.
How do carbohydrates work?
Remember, glucose is the usable form of carbohydrate. All carbohydrates (sugars and starches) must be broken down to glucose. This process is called digestion.
Monosaccharides (fructose, glucose, galactose) are absorbed rapidly from the small intestine into the bloodstream where they travel to be used as a source of energy by cells. All other carbohydrates (polysaccharides) have to be cleaved apart by digestion in the small intestine.
We used to think of carbohydrates as two different forms, simple and complex. However, this tells us little about how different carbohydrates behave in the body(8). It was widely believed that complex carbohydrates such as rice or potatoes were slowly digested and all simple carbohydrates (sugars) were absorbed rapidly. However, scientific research examining real human digestion demonstrates that these assumptions are wrong(6).
As bodybuilders and athletes, we need to forget the words simple and complex when talking about carbohydrates. We need to think in terms of low Glycemic Index and high Glycemic Index carbohydrates.
What is the Glycemic Index?
Because of the profound impact on our health, scientists have started to investigate the physiological response of different foods on blood sugar levels. The glycemic index (GI) of food is a ranking of foods based on their immediate effect on blood glucose (blood sugar) levels.
The GI ranks food on a scale from 0 to 100 according to the extent to which it raises blood sugar levels after eating. Carbohydrate foods that break down quickly during digestion have the highest glycemic index rating. Their blood sugar response is fast and high. The substance which produces the greatest rise in blood sugar is pure glucose. Therefore, the GI of glucose is 100.
Every other food is ranked between 100 and 0. Carbohydrates that break down slowly, releasing glucose gradually into the bloodstream, have a low glycemic index(6). Foods with a high GI produce a great surge of glucose into the bloodstream. This surge in blood glucose is matched by another in insulin in an attempt to control blood glucose levels.
High GI foods produce marked fluctuations in blood glucose levels. Low-GI foods, by their slow digestion and absorption, produce gradual rises in blood glucose and insulin levels and have proven benefits for health.
Why is the GI factor so important?
Quite simply, by selecting foods with the GI factor in mind, you will decrease the amount of insulin secreted and promote insulin sensitivity within tissues. This strategy makes insulin more efficient within your body.
The GI concept was first developed in 1981 by Dr. David Jenkins (a professor of nutrition at the University of Toronto, Canada) for diabetics as an aid to food selection to help insulin management. This initial work has been expanded tremendously by scientists of the University of NSW, Sydney Australia. The GI factor is now a medically accepted nutritional strategy to help prevent and control type 2 diabetes, heart disease, and obesity (6).
For the drug-free bodybuilder, knowledge of the GI index of carbohydrate foods is invaluable.
1. It allows you to control and manipulate natural insulin secretion to obtain the maximum anabolic effect from your training.
2. Manipulating insulin levels in the hours after intense training will facilitate maximum nutrient transportation into muscles, accelerating recovery and cellular adaptation.
3. One of the hardest parts of fat loss for definition is feeling hungry all the time. This gnawing feeling is not necessary to lose fat. Low GI foods are natural appetite suppressants.
4. Controlling insulin by using the GI factor of foods ensures fat is burned, and the anabolic drive is maintained all day, every day.
It’s all in the Digestion
What makes one carbohydrate different to another regarding its GI rating? This all has to do with the physical state of the carbohydrate in the food. When carbohydrates are consumed in their natural packaging, such as whole or intact grains, oats, barley, whole wheat and vegetables, the food will take longer to digest (break down), and its monosaccharides will enter the bloodstream slowly. These foods will have a lower GI factor.
Therefore, the whole grain or unprocessed food will always have a more gradual, prolonged effect on blood sugar. (There are some exceptions to this, such as potatoes and different forms of white rice.)
The other aspect that governs digestion of a carbohydrate is the ratio of two separate types of starches the food has. These two starches are called amylose and amylopectin.
To put it simply, amylopectin molecules are larger, more open and easier to digest. Thus, foods that have little amylose and plenty of amylopectin within their carbohydrate will be more rapidly digested and absorbed into the bloodstream and will possess a higher GI number. Some examples of high amylopectin to amylose carbohydrate foods are wheat flour and Calrose white rice. These foods have high GI numbers.
Some foods that have more amylose than amylopectin are basmati white rice, durum wheat pasta and all sorts of legumes. Therefore, these carbs possess low GI numbers.
The Sugar Myth
Many people believe a healthy diet means avoiding all sugar. Remember, sugar (sucrose) is two molecules joined together (a disaccharide). Sugar is one molecule of glucose joined to one fructose molecule.
Fructose is the one single sugar which is an exception to the GI rule. To be made usable, fructose must travel to the liver, where it is slowly converted to glucose. So the blood sugar response to fructose is very small, it has a GI rating of only 20.
So when we consume normal sugar (sucrose), half of this is glucose and half is fructose. Sucrose has a GI rating of 60-65. Pure glucose has a GI rating of 100.
Compare this to another type of disaccharide called maltose, which is two glucose molecules joined together. Maltose has a very high GI of 95-100, quite a big difference to sucrose. Therefore, it pays to know the difference between your sugars.
Contrary to popular opinion, most foods containing “sugar” per se, do not raise blood sugar levels any greater than most bread or commercial cereals. Remember, however, that volume is still important.
The GI rating of food is based on the blood sugar reading obtained from 50 grams of that particular carbohydrate food.
While 50 grams of pure glucose (a refined carbohydrate) is a few spoons, it takes 700 grams (1 and a half pounds) of carrots to obtain 50 grams of carbohydrate. So if your name’s not Bugs Bunny, which food would you most easily consume excessive calories?
Weight loss and fat loss still come down to the number of calories you take in versus the amount you burn on a daily basis regardless of GI factor. However, knowing the GI factor of carbohydrate foods makes it easier to avoid hunger pangs and stay within your caloric range and lose fat!
The GI Carbohydrate List for Building Muscle and Losing Fat
Think of the GI rating of every carbohydrate food in terms of a preference list. From the top of the list, carbohydrates with a high GI rating (between 100-60) are the carbohydrates best suited to consume in the hours directly after training as they increase blood sugar and insulin levels rapidly.
The 3-hour window after training is the best time to consume small portions of high GI foods. High GI foods are usually the sweetest tasting, most refined (packaged) and in the simplest forms such as glucose and wheat flour. Some are unsuspected foods such as baked potatoes, white bread, some forms of white rice and most commercial breakfast cereals. These are all high GI foods.
Consuming high GI carbohydrates with VP2 Whey Isolate in the 3-hours after training stimulates insulin production even further. It also provides an abundance of readily absorbed amino acid peptides to muscle. These two factors turn the anabolic stimulus of resistance training into net gains in muscle mass.
After the 3-hour Post-training Window
Carbohydrates that produce a lower, more constant insulin response are termed low GI foods and usually possess numbers under 60. After the initial 3-hour, post-training period, to facilitate optimal nutrient transport into muscle cells and maintain steady state blood glucose and insulin levels, you should select from this category of foods.
By rule of thumb, when you examine the list you will find virtually all low GI carbohydrates are unrefined, whole foods such as vegetables, legumes, and whole grains. These foods are unprocessed and naturally high in fiber. Ironically, anytime man has processed food to suit convenience it has eliminated the nutrients the food was designed to provide! This messes with our biology.
Low GI carbohydrates eaten at regular intervals during the day contribute to your health by increasing insulin sensitivity of cells and promote constant, steady release of energy and uptake of nutrients into muscles. Low GI carbohydrates maintain the optimal muscle-building environment by maintaining blood glucose and insulin within a low range. This prevents hunger pangs, energy slumps during the day, and promotes body fat loss.
What about a mixed meal?
Because we rarely eat carbohydrate foods on their own, Associate Professor Jennie Brand-Miller and her colleagues at the Department of Biochemistry at NSW University have come up with this neat, yet simple method of how to calculate the GI factor of any mixed meal you may consume. We will be providing more information soon.
However, you don’t need to get too technical if you don’t want to. Just remember the following rules.
1. High fiber foods such as vegetables and salads tend to lower the GI rating of a meal and slow the absorption of glucose into the bloodstream. For fat loss and gains in muscle, this is a good thing.
2. Foods high in protein (meats, chicken, fish), when eaten with carbohydrate foods, tend to lower the GI factor of the meal. On most occasions, this also is a good thing for fat loss and muscle gain.
3. Any food high in fat also tends to have a low GI rating. This is because of its slow absorption. However, this isn’t necessarily a good thing. Corn chips and ice cream will still make you fat, despite their low GI rating.
Not all Carbohydrates are the Same
One common fault athletes mistakenly assume is that all forms of pasta, rice and other starches that make up our carbohydrate choices are the same. Regarding their impact on blood glucose and insulin levels, there can be a huge difference.
All pasta are not the same regarding GI rating(6). Pasta made from wheat flour has a high GI number of 80, whereas Durum wheat or Semolina makes the best pasta for athletes with a GI of 40. These are extremely hard forms of wheat and break cleanly into distinct pieces. The large particle size of this starch makes it difficult for enzymes to attack and digestion is much slower.
There is also a big difference in various forms of white rice, a staple food of bodybuilders. Calrose white rice has a starch ratio very high in amylopectin and low in amylose. This means rapid absorption. Consequently, Calrose rice has a GI factor as high as 95!
Other forms of rice such as Doongatti and Basmati are the opposite. They have a high amylose to amylopectin ratio and consequently possess a GI factor of 40-50. This can make a big difference to your blood sugar levels, particularly if you rely on rice for energy during your dieting phase.
So learn the GI numbers and read your food packets in the supermarket before you buy. All whole-food carbs aren’t the same.
The Powerful Effects of Lemon Juice, Vinegar, and Sourdough
The acidity of a food or meal tends to lower the GI factor of a meal. Adding as little as 20 milliliters of vinegar to a meal is shown to drop the GI factor of a meal tremendously. Lemon juice also appears just as powerful. Sourdough bread, in which lactic acid and propionic acid are produced by natural fermentation, also appear to have a GI lowering effect on a mixed meal.
Using foods high in acidity tends to pull the brake on stomach emptying and slowing the delivery of food to the small intestine. Slower digestion means a less dramatic rise in blood sugar, no energy slumps, and steady insulin secretion. So keep adding that vinegar and lemon juice to your side salads and meals. It’s doing more for you than simply adding flavor.
Making the GI Work for You
The GI approach to eating is the way nature intended us to eat. She packaged all the nutrients we need in a slow release form. It is only modern living that has screwed around with this formula and turned many of our foods into fast release with little digestion for a more delicious, eye-catching, non-perishable food supply. Now the effect of all those instant, artificial foods is catching up with us in the form of diabetes, heart disease, and weight gain.
Simply by being aware of the type of carbohydrates you eat and when you eat them can dramatically accelerate your results from weight training.
Selecting foods with high GI numbers directly before and after will create the optimum environment to accelerate muscle growth. Then, for the other 21 hours of the day, by selecting carbohydrates from the lower end of the GI scale you will maintain steady blood glucose and insulin levels that maintain the anabolic drive and maximize your muscle-building and fat loss efforts.
References
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3. Philips LS, Fusco AC,Unterman TG. Metabolism, 34:765-770,1985.
4. Carroll PV, Christ ER, Umpleby AM, et al. Diabetes. 49(5):789-96,2000.
5. Kraemer WJ, Volek JS, Bush JA, et al. J.Appl.Physiol.85(4) 1544-1555,1998.
6. Brand-Miller J, Foster-Powell K, Colagiuri S, Leeds A. The GI factor. Hodder Publishing 1998.
7. Heaton KW, Marcus SN, Emmett PM, Bolton CH. Am. J.Clin Nutr.48:496-502,1994.
8. Brand-Miller J, Beebe C. Presented at the 60th Scientific Sessions of the American Diabetes Association; June 13, 2000; San Antonio, Texas.
