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Running and Carbohydrate Intolerance

European Running Championship
Peter Giles

Peter Giles: ON RUNNING

When I was there, there was an Inter-House Cross Country race every year at Bournemouth Grammar School. Without any particular training, I used to finish first or second out of the 150 boys in my year. Thereafter, I played football and cricket for local teams for many years. It was not until I was 44 years old when I married Yasmine, that I started running competitively! I had always wondered what standard I could achieve - Club, County, National, International? - as my schoolboy efforts had indicated a natural ability.

When I reached 60 years old, I was still racing at 6 minute/mile pace for 10 kilometres. This prompted me to apply for the England Masters’ Cross Country team which competed in the Five Nations International Cross Country every November. I was selected! So I had now gone from club and county to national standard.

During the next ten years, I represented England many times. Then in 2015, I entered my first World Masters Track Championships which was held that year in Lyon, France. I won three medals: Individual Silver for the 1500m, Bronze for the half-marathon and Team Gold for the half-marathon (our GB M70 team finished 2nd, 3rd and 4th!).

So finally I had reached world class status. And I shall be competing in Sweden this August in the World Masters Championships in search of my first Individual Gold Medal.

Apart from training sensibly, I have found that eating the right foods - or at least avoiding the wrong foods - has been crucial to my health, fitness and good looks (you’re kidding, right? - Ed).

Hence I am now presenting the articles below for your perusal.

They were written by Dr. Philip Maffetone who has many years’ experience of guiding sportspeople of all abilities to success by taking a more holistic approach to their training and competing.

I hope that you find his writings as helpful and inspiring as I have done.

Yours in Sport, Peter

Excerpts taken from ‘The Big Book of Endurance Training and Racing’ by Dr. Philip Maffetone with his permission and our thanks

Expert on Endurance Training
Philip Maffetone


Types of Carbohydrates

All carbohydrates are composed of single sugar molecules that exist in three forms - glucose, fructose, and galactose:

• Complex carbohydrates, also called starches (polysaccharides), contain many single sugars attached together: for example, many glucose molecules held together (glucose + glucose + glucose). These carbs can be found in potatoes, corn, all grains, and beans.

• Double sugars (disaccharides) are made up of two sugars attached to each other.

They include sucrose (glucose +fructose), lactose (glucose + galactose), and maltose (glucose + glucose). These are found in table sugar (sucrose), milk sugar (lactose), maple syrup (maltose), and other "malt" sugars, such as maltodextrin.

Simple sugars (monosaccharides) contain single, unattached sugars.These are found in ripe fruits and vegetables and honey, all of which have various amounts of glucose and fructose.

Unripe fruits and vegetables contain higher amounts of starch and double sugars. During the ripening process, these complex carbs and double sugars are converted to simple sugars, making ripe fruit taste sweeter. As an example, green bananas turn yellow (with black spots) when ripe. Even vegetables are sweeter when ripe: green peppers are unripe and turn red (or yellow) when ripe. Because most of the sugars contained in these plant foods are broken down to simple sugars, no further digestion of these carbohydrates is needed. For some people, eating unripe fruit or vegetables is the reason they get indigestion.

It's most important to understand this aspect of carbohydrates: Both complex carbs and double sugars require digestion in order to break apart the simple sugars that are attached to each other. This must occur in order for sugar to be absorbed and made available for energy. Complex carbohydrates require the most digestion. Simple sugars don't require digestion; they are immediately available for absorption.

During the process of digestion, both complex and double-sugar carbohydrates are chemically broken down to their simple sugars (monosaccharide).

Digestion occurs primarily in the mouth and small intestine. Once digested, the sugars are absorbed into the blood and are then referred to as "blood sugar.”

Complex carbohydrates and double sugars often don't completely digest into their simple sugars. This may be due to insufficient chewing of food in order to mix it with the enzymes in saliva, common during the stress of competition or long training. Those incompletely digested carbohydrates can cause significant amounts of intestinal gas, causing discomfort or often pain. We've all experienced this type of stress in our intestines during physical activity.

One problem with a high amount of refined carbohydrates in the diet is that they take the place of other healthy foods - fats, proteins, and vegetables. For endurance athletes, this can produce inadequate nutrition as well as reduced fat burning and aerobic function.

While many scientists believe that humans have no true requirement for carbohydrates (because fat and protein can be converted to glucose), many people consume refined carbs as a staple of their diet and in very high amounts. In fact, most athletes consume the majority of their carbohydrates as the refined, processed type.

Carbohydrates and Insulin

When we consume carbohydrates, most are broken down to glucose and absorbed into the blood. The rise in blood sugar immediately triggers the release of the hormone insulin from the pancreas. Insulin is a very important hormone but too much adversely affects one's endurance and health, especially by reducing the ability to burn body fat.

Insulin allows us to use. and store glucose, and as this happens, blood sugar is lowered. Insulin works through three different mechanisms:

About 50 percent of the blood sugar (about half the carbohydrates you eat) is quickly used throughout the body for energy, especially in muscles and the brain.

Up to about 10 percent of the carbohydrates you eat are converted to glycogen, a storage form of sugar. The glycogen is stored in the muscles and liver. The amount depends on the level of your glycogen stores. (Muscle glycogen, for example, is converted back to glucose for energy, and liver glycogen helps maintain blood sugar levels between meals and during nighttime sleep.)

About 40 percent or more of the carbohydrates you eat is converted to fat and stored as body fat. This is the source of fat used by the aerobic muscles for energy, but if the fat- burning mechanisms are not working well, or if too much carbohydrate is consumed, fat stores can get larger.

Insulin is produced whenever you eat carbohydrates, except when you consume them during training or competition. Insulin levels are reduced during physical activity, helping the body burn more fat for energy. Smaller amounts of insulin may also be produced if you consume a protein-only meal, and in some people, a high- protein meal can stimulate significant amounts of insulin.

But for most people, it's predominantly carbohydrates that trigger the insulin mechanism. As noted, too much insulin causes problems for endurance athletes, as can too little (a problem for diabetics).

In the past several decades, the high consumption of highly refined carbohydrates has contributed significantly to the obesity epidemic and other chronic illness such as diabetes and heart disease. In addition, there is an "overfat" (as opposed to "overweight") problem, even among athletes. The trend in carbohydrate over- consumption continues today, propelled by companies selling refined carbohydrates and sugar. This is quite prevalent in the endurance sports market.

During most of our evolutionary history, humans lived near the sea and consumed significant amounts of fish, seafood, and other land-animal proteins. More importantly, large amounts of plant foods were also part of our diet. These included vegetables, fruits, nuts, and seeds. In addition, our ancestors were very active physically, even more than most endurance athletes today. Only in the last five-thousand years has this changed. The agricultural revolution brought a dramatic increase in carbohydrate foods and the industrial revolution brought highly refined carbohydrates to the table.

The intake of refined carbohydrates by humans has never been as dramatically high as in just the last one hundred years. This relatively short period of significant dietary change has contributed to the overfat problem, and to many problems leading to heart disease, cancer, obesity, and other diseases. This is due, in part, to the over-consumption of refined carbo- hydrates, higher levels of insulin production, higher fat stores, and chronic inflammation.

The more carbohydrates consumed, the more insulin produced by the pancreas. Even healthy people can overproduce insulin by eating excessive amounts of carbohydrates. While this problem is thought to occur in those who are overfat, it can also occur in lean people as well.

This potentially leads to a condition referred to as "insulin resistance" associated with the inability of insulin to efficiently fuel the muscles with glucose. As a result, energy is reduced, along with fat burning. Hunger is another result--because the cells don't get enough energy, each time these people eat carbohydrates, the brain gets the message that the cells don't have enough sugar and the brain tells the pancreas to make more insulin.

Finally, insulin is produced beyond normal limits, a condition referred to as "hyperinsulinism." While it takes more insulin to get glucose into the insulin- resistant cells efficiently, this hormone continues to perform its other tasks, including turning carbohydrates into fat for storage.

In addition to causing even more carbohydrates to convert and store as fat, excess insulin can continue lowering the blood sugar - because that's one of its functions, including converting glucose to fat. Since the brain exclusively relies on glucose for fuel, periods of reduced blood sugar can result in impaired mental function, including loss of memory, reduced concentration, and other cognitive impairments. Low blood sugar also results in hunger, sometimes only a couple of hours or less after the meal. Cravings for sweets are typically part of this cycle and resorting to snacking on more carbo- hydrates maintains the vicious cycle. And if you don't eat, you just feel worse.

Eventually, the fat-storage deposits get bigger. While this problem can be relatively minor, in some athletes it can cause a more serious condition, such as higher body fat or even diabetes, the full spectrum of this carbohydrate problem is a condition I term carbohydrate intolerance, discussed below.

High insulin levels also suppress two important hormones: glucagon and growth hormone. Glucagon has the opposite effect of insulin and is produced following protein consumption. While insulin promotes fat storage, glucagon promotes the use of fat and sugar for energy. Growth hormone helps provide many of the endurance benefits we obtain through training, including muscle development, sugar and fat burning, and the regulation of minerals and amino acids.

Glycemic Index

The general measure of how much your blood sugar increases after eating specific carbohydrates is called the glycemic index (GI). This is associated with the amount of insulin produced. The GI is a general measure of individual responses to particular carbohydrate foods: however, individual variation is not considered in studies of foods and their glycemic effects.

High-GI foods, which produce the greatest glucose response (and highest insulin), include bagels, breads, potatoes, sweets, and other foods that contain refined flour and sugar. Many processed cereals, especially those containing malt sugars (maple syrup, maltose, maltodextrin, etc.), have a very high GI.

Carbohydrate Intolerance

With generations of people over-consuming refined carbohydrates, many now have a health problem I have termed "carbohydrate intolerance," or CI. It's a widespread phenomenon. Though most people are unaware such a condition even exists in its early stages, a high percentage of the population suffers from CI in all stages. The symptoms of early CI are very common and include sleepiness after meals, intestinal bloating, increased body fat, fatigue, and many others as shown in the survey below. The middle stages of CI are often accompanied by higher blood fats - especially triglycerides but also cholesterol - and hypertension. Later stages include diabetes, obesity, cancer, and heart disease.

The early stages of CI can be vague, often unrecognized by health-care professionals and lay people alike. A variety of names and changing definitions have been used by organizations like the ADA (American Diabetes Association) and WHO (World Health Organization) in relation to these abnormal carbohydrate and glucose problems. All this is an attempt to better understand the issues, although more comprehensive standardized definitions are still lacking. We know there's a full spectrum of carbohydrate (glucose) function in the body, from the normal, healthy condition to the other extreme of diabetes. In between are many abnormal states, some more mild and others more serious. Many people go through life progressing through part of, or the entire spectrum. Rather than getting confused about defining the different stages (an important task for researchers and clinicians), it's best to just call this full spectrum carbohydrate intolerance.

Many clinicians discuss this full spectrum of CI from a standpoint of glucose: there's normal glucose and impaired glucose. Depending on test results and their interpretations, a concoction of names has resulted, which has continued to confuse health-care professionals and lay people alike. For example, common classifications of early. stages CI include impaired glucose metabo- lism, impaired blood sugar, glucose intolerance ,and others. Insulin resistance and hyper-insulinemia are names applied in later, more chronic conditions.

Even the term hypoglycemia, originally only discussed in relation to diabetics,is a condition now known to occur in individuals who are free of measurable disease. Further confusion exists because some hypoglycemic reactions are normal; it's the abnormal form that exists as a result of excess insulin production.

Like most problems, CI is an individual one, affecting different people in different ways. Only you can determine how intolerant you are to carbo-hydrates and to what degree. Blood tests will diagnose the problem only in the middle and later stages, but the signs and symptoms may have begun years earlier. The key to avoiding the full spectrum of CI is to be aware of it in its earliest stage and to make the appropriate diet and lifestyle changes. This can improve athletic performance and quality of life immediately, and prevent the onset of disease later.

Following is a list of some common signs and symptoms of various stages of CI. Many complaints occur immediately following a meal heavy in carbohydrates. Keeping in mind that these signs and symptoms may be related to other causes, ask yourself if you have any of these problems:

Physical fatigue. Whether you call it fatigue or exhaustion, the most common feature of CI is that it wears people out. Some are tired just in the morning or afternoon; others are exhausted all day.

Mental fatigue. Sometimes the fatigue of CI is physical, but often it's mental (as opposed to psychological); the inability to concentrate is the most evident symptom. Poor memory, failing or poor grades in school, and loss of creativity often accompany CI, as do various forms of "learning disabilities." This is much more pronounced immediately after a meal, or if a meal is delayed or missed. The worker who returns to his or her job site after lunch, only to be unable to concentrate due to mental fatigue, is a very common example. Some actually fall asleep at their desk after lunch.

Blood sugar problems. The blood sugar may be normal until a carbohydrate meal is consumed, or if meals are not eaten on a regular schedule. Periods of erratic blood sugar, including abnormal hypoglycemia, accompanied by many of the symptoms listed here, are not normal. Feeling jittery, agitated, and less of whether the blood pressure is elevated, moody is common with CI and is relieved almost immediately once food is eaten. Dizziness is also common, as is the craving for sweets, chocolate, or caffeine. These symptoms are not necessarily associated with abnormal blood sugar levels but may be related to neurological stress, possibly due to the rapid changes in blood sugar and insulin.

Intestinal bloating. Foods that produce the most intestinal gas are complex carbohydrates, specifically starches, such as wheat products and potatoes, and other non-starch carbohydrates such as sugar. People with CIoften suffer from excessive gas production. Antacids, or other remedies for symptomatic are not very successful in dealing with the problem. The gas tends to build and is worse later in the day and at night.

Sleepiness. Many people with CI get sleepy immediately after meals containing more than their limit of carbohydrates. This occurs typically after a pasta meal, or even a meat meal that includes bread, potatoes, or dessert.

Increased body fat. For most people, too much weight is also too much fat. Often the location of this excess body fat is unique between the sexes. In males, an increase in abdominal fat is more evident and an early sign of CI; this leads to a "carbo belly." In females, fat storage is often more prominent in the upper body; in a woman's face.

Increased triglycerides. High triglycerides in the blood are often seen in people with CI. These triglycerides are the direct result of carbohydrates from the diet being converted by insulin into fat. In my experience, fastingtriglyceride levels over 100 mg/dl may be an indication of a carbohydrate intolerance problem (even though 150 and above is considered normal).

High blood pressure. Most people with hypertension have CI. There is often a direct relationship between insulin levels and blood pressure - as average insulin levels elevate, so does blood pressure. For some, regardless of whether the blood pressure is elevated, sodium sensitivity is common, and eating too much sodium causes water retention along with elevated blood pressure.

Depression. Because carbohydrates can be a natural ‘downer’, depression is common among people who have CI. Carbohydrates do this by adversely affecting levels of neurotransmitters made in the brain, producing feelings of depression. Many people have been taught that sugar is stimulating, but actually the opposite can be true. Some people have a short, initial burst of energy after eating sugar - but it does not last.

Further more, the medical history of you or your immediate family may indicate a vulnerability to CI. This includes a personal or family history of diabetes, kidney or gallstones, gout, high blood pressure, high cholesterol/low HDL, high triglycerides, heart disease, stroke or breast cancer.

Certain types of people are more vulnerable to CI, including those who are under more stress, taking oestrogen, dark skinned people, and those with a family history of diabetes or other metabolic syndrome diseases. In addition, aging is frequently accompanied by increased carbohydrate intolerance.


Carbohydrates, especially sugar, can be addictive. Some people have trouble accepting this notion because, surprisingly, there are no clear scientific studies to demonstrate that claim. Many health-care professionals have struggled to help patients who could not reduce or eliminate sugar despite its unhealthy hold on them.

While we don't have a clear scientific study that shows addictive properties of sugar or other refined carbohydrate foods, studies do show that sugar and high- glycemic foods can trigger the brain's reward centers. These are the same brain areas stimulated by cocaine, nicotine, and other widely accepted addictive substances.

The fact that sweet-tasting and so-called comfort foods can be addictive is well accepted - and even proven - by the very companies who employ marketing as a powerful tool to sell these products. Food advertisers who spend billions of dollars each year know very well about addiction and how to tease and tempt you with foods that can end up killing you. These ad campaigns are especially successful with teens and children, and they are not unlike those used by the tobacco industry for so many decades. Just look at the beverage giants like Coca-Cola and Pepsi. Each twelve-ounce can may contain forty grams of carbohydrates, or about nine teaspoons of sugar. In late 2009, Coke came out with a smaller-size can, marketing it as a “healthier alternative" since it has fewer calories!

If society truly recognized the real harm caused by refined carbohydrates, especially sugar, much like what has happened with cigarettes in recent years, there would be a revolution by consumers. State, city, and even federal government agencies would place a huge tax or outright ban on sugar and refined carbohydrate foods due to the astronomical cost of healthcare associated with their use. Companies that make cereals, candies, cookies, and sugar itself would be sued, much like the tobacco class-action lawsuits. I can imagine the secret after-school cookie deals, or sugar by prescription only, and the growth of sugar addiction clinics where the treatment of choice would be artificial sweeteners. Well, things may be heading that way.

Wheat: An Unhealthy Food Staple

Wheat may be the most unhealthy food staple of the Western diet next to sugar and contributes significantly to ill health and dis-ease. We all know how bad sugar is for health due to its high-glycemic nature but wheat and wheat products can actually be worse due to an even higher glycemic index. Eating that piece of bread is not unlike eating several spoonfuls of white table sugar, and your body turns much of this wheat into fat. Almost half of that so-called fat-free bagel can end up becoming stored fat.

Wheat is a lobbying success story, like the tobacco industry, as it's found in most people's media-driven diets. It's certainly not recommended for nutritional reasons as we can obtain whatever nutritional benefits wheat contains from many other healthy foods. And considering the health risks, wheat's place on any food pyramid can only be a scheme that serves those who are addicted and the companies that sell it.

Wheat is a common cause of intestinal problems, allergies and asthma, and skin problems; it can prevent absorption of various nutrients, contribute to weight gain, and occasionally causes death.

The reason for wheat's failure as a healthy item is twofold: the protein component of wheat, called gluten, causes allergies in many people, including infants who are unfortunately given this as their first food. And many people are adversely affected by gluten without realizing it, through a slow, silent buildup of chronic illness. Gluten is what makes bread rise, so most baked goods and packaged foods are full of it.

The second reason wheat is unhealthy is that almost all wheat products are high glycemic-from bread, bagels, and muffins to cereals and additives to many packaged foods to wheat flour itself, a staple in almost all kitchens and recipes. Gone are the days when people would buy real wholewheat berries, grind them, and make flour or sprout them for use in food products. While the berries still contain gluten, they're not high glycemic. But almost all wheat used today is highly pro-cessed, making it high glycemic.

The list of specific conditions associated with consuming wheat keeps growing - from autoimmune diseases (such as arthritis, type 1 diabetes, lupus, MS) and chronic inflammation to infertility and skin disorders (such as eczema, acne, and psoriasis), and even cancer. Some people are more sensitive to the harmful effects of wheat than others. Wheat is among the most common cause of allergies in children and adults, along with milk, soy, peanuts, and corn. The most practical way to assess this is to note how you feel after ingesting wheat. The most common symptom is intestinal bloating, but signs and symptoms are associated with skin, breathing, and edema, and may be immediate or delayed. If you're sensitive to wheat, significantly reducing or eliminating it from your diet is the most effective remedy.

Here are some other points regarding wheat's harmful effects:

In the intestines, wheat can prevent the absorption of important minerals. These include calcium, magnesium, iron, zinc, and copper - all essential for good health.

Wheat can reduce digestive enzymes, especially those from the pancreas, rendering key foods less digestible--including protein and fats. Not digesting protein impairs amino acid absorption, and whole protein absorption can cause allergies. And if fat is not digested, essential fatty acids may not be absorbed, adversely affecting a whole spectrum of problems from skin quality to inflammation and hormonal balance.

Since refined wheat is higher glycemic, it can lead to the production of higher amounts of insulin by the pancreas. In addition to causing more fat storage, this can also increase your risk of various diseases including diabetes, cancer, and heart disease.

Combining exercise and wheat can trigger allergic reactions in some people, although it's not common. This occurs when a person eats some form of wheat and exercises within a given time period. This is followed by some allergic reaction, from mild problems (some- times so mild people are used to it) like skin rash or hives to more severe problems including anaphylaxis and, in rare occasions, even death. This may also include breathing difficulty. It is sometimes difficult to diagnose because of the need for both triggers (wheat and exercise)around the same time period. It's conceivable that some of the deaths reported in athletes are due to this problem.

High-glycemic wheat products, which are often sweetened with more sugar, can result in a sweet tooth--or addiction--that not only perpetuates the desire for more sweets. but the dislike for health-promoting but bitter orless sweet-tasting foods, like vegetables.

Wheat can sometimes cause mental or emotional symptoms, including depres-sion, mood swings, attention problems in children, and anxiety. One long-term illness associated with wheat allergy is dementia due to cerebral (brain) atrophy.

Osteoporosis may be strongly associated with wheat allergy.

Other quality of life issues can also be associated with wheat consumption. These include belching or gas, diarrhea, or other abdominal discomfort; reduced mental focus and poor concentration; and fatigue - some people actually fall asleep after a meal containing wheat, even just a sandwich.

A serious wheat-intolerance problem once thought of as rare is celiac disease, an autoimmune condition where patients must avoid any amount of wheat or risk serious, sometimes life-threatening reactions. Many professionals agree that even mild forms of wheat allergy are really the same thing - a sub-clinical celiac condition.

In fact, this problem is more recognized today, with a recent article in the Journal of Family Practice showing that for every person diagnosed with celiac disease, there are eight others who go undiagnosed. Millions of Americans - including endurance athletes - and many more people throughout the world have this condition.


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