The carbo-loading question: Who should avoid it?

Carb Loading

Most people are familiar with the notion that increasing carbohydrate intake before competition can increase energy stores. But for some there may be real dangers to carbo-loading. Here are eight good reasons to question this time-honored but potentially damaging tradition.

Risky behavior dies hard. So do dangerous sports traditions. Put them together in a no-pain no-gain society, spurred by media and advertising campaigns encouraging people to stuff their faces with sugar and other junk food, such as unhealthy carbs, which work well during competition but not as a meal or snack, and you risk poor health and declining fitness in those who exercise.

Can carbohydrate-loading be one of those dangerous routines that add both excess body fat and slower endurance performance? Most certainly, yes. And the studies show this trend: In the U.S., for example, exercise rates are increasing while the overfat pandemic continues growing. Plus, performance rates (road running finish times in all but the lead packs) have been declining during the decades-old carbo-loading trend. But we can’t run away from a bad diet.

A common notion in sports is that eating more carbohydrate increases energy and glycogen stores. While this is true, we can only obtain a certain amount of both, so forcing more carbs won’t make much difference in giving us more energy or greater glycogen stores. Actually, about half the carbs consumed are converted to stored fat, and all this refined carbohydrate produces excess insulin, which reduces the use of stored fat for energy.

Fat stores offer virtually unlimited energy. So if you already have too much body fat, you are best reducing carbohydrates during meals and snacks to burn more stored fat for energy, using glycogen stores for a reserve or, during competition, for the final kick to the finish line.

Humans have always had the ability to perform well on low- and even very-low carbohydrate intake by adapting to burn fat for fuel. This mechanism relies on abundant fat stores to energize endurance training and performance. Even a lean athlete has 30,000 to 60,000 kcal of fat for potential energy, enough to run hundreds of miles. Meanwhile, stored carbohydrate in the form of glycogen is only about 2,000 kcal, not enough energy to get anyone through a 42k marathon.

Make the switch to healthy carbs

Unhealthy Carbs

  • Almost all pancakes, muffins, bagels, breakfast cereals, etc.
  • White potatoes, pasta, corn.
  • Sugar and sugar-containing snacks/desserts, bananas, watermelon, dried fruit, fruit juice; sports drinks and energy bars.

Healthy Carbs

  • Stone-ground flour and cereal products like long-cook oatmeal (40+minutes).
  • Lentils, beans, sweet potatoes.
  • Fresh apples, pears, berries, melons, avocados, citrus, peaches, vegetable juice.
  • Honey.
  • (See Phil’s Bar and Phil’s shake recipes).

It’s the refined carbohydrates that pose the problem for everyone, while natural ones — fruits, beans, lentils, oatmeal, sweet potatoes — are potentially nutritious based on the individual’s level of insulin resistance.

The idea that refined carbohydrate in all its many forms is unhealthy comes with decades of scientific research — laboratory studies, clinical trials and epidemiological analyses — and careful clinical observations. In fact, among what may be the most common population of carbo-loading people — amateur runners — we clearly see that, not only have running race times been slowing down for many years, but physical, biochemical and mental-emotional injuries are very common, including the metabolic problem associated with the overfat pandemic, which has not spared athletes.

This is not to say the use of sports drinks, gels and other carbohydrate supplements during competitive performance is unhealthy or not effective; it is something I have always recommended. But using these carbohydrates as a down-time snack or part of regular meals can be devastating to human metabolism and one reason carb-loading is dangerous.

Unfortunately, most of the carbohydrate foods consumed by athletes today are refined and unhealthy. They are high-glycemic, processed, contain added sugars or quickly turn to sugar after eating. Eating these low-quality foods (sometimes termed empty calories) replaces potentially higher quality more natural and nutritious foods necessary to support athletic performance and health.

Eating refined foods for carbo-loading, which may take place over relatively shorter vs. longer periods of time, can change metabolism and adversely affect health and performance. Even just a day of high-carb eating — or just one meal or snack — can negatively impact metabolism. Moreover, these insulin-provoking foods consumed before your workout can also reduce fat-burning, risking keeping more fat in storage and using up too much glycogen.

Over the past few decades, unhealthy carbohydrate consumption has rapidly and steadily risen, as high carbohydrate eating is now the norm. To a great extent, it’s thanks to sugar addiction, low-fat obsession, and the anti-meat myth. If you reduce dietary fat and protein, carb intake soars. These processed, refined carbs digest quickly, release abnormally high amounts of the hormone insulin.

Insulin production from refined/high-glycemic carbohydrates can be double that of low-glycemic natural carbs, which also reduces the production of glucagon. This hormone imbalance can result in low blood sugar (causing fatigue, weakness, hunger, and ultimately, significantly increased caloric intake). This can linger for hours after a meal, and trigger a cascade of other hormone problems. And, higher insulin meals prevent weight/fat loss while low-glycemic low insulin meals help with weight/fat loss.

Higher insulin levels also can increase the production of cortisol, the primary stress hormone that can impair the brain, muscle function, endurance, and increase fat storage, especially in the belly. And it can disturb sleep, potentially impairing recovery from training. This metabolic trauma can be worse in those with excess body fat.

In addition, higher insulin levels can also increase inflammation and pain (chronic inflammation is also associated with the early onset of chronic disease). High insulin is also associated with increased oxidative stress and reduced antioxidant levels, already a problem in those who train hard and compete, speeding aging and breaking down immunity.

So who should avoid carbo-loading? Here are eight important reasons — avoid it if:

  • You are carbohydrate intolerant (insulin resistant). Higher insulin production reduces the body’s ability to burn body fat, keeping too much fat in storage and not available for energy. While testing can determine the existence of this problem, the easiest way to know is to measure your waist-to-height ratio. It’s an accurate overfat indicator, and those with excess body fat are usually carbohydrate intolerant. Consuming more carbs can make you even more carbohydrate intolerant.
  • Your body does not do well with change. The radical dietary shift to carbo-loading leading up to competition can be a significant added stress, which can ruin performance.
  • Overconsuming carbs causes excess/uncomfortable intestinal distress — bloating, gas, gut discomfort, especially during carbo-loading or during training or competition.
  • You become fatigued or hungry during the carbo-loading period (or are that way often). These symptoms may be due to excess insulin production.
  • You have a family or personal history of cardiovascular disease, cancer, Alzheimer’s or diabetes. Increased high-glycemic carbohydrates can further increase the risk.
  • Your blood pressure is above 120/80, or have abnormal blood fats (HDL, LDL, triglycerides).
  • You have injuries, pain or ill health (usually indicative of chronic inflammation).
  • Doing it doesn’t make you feel at least as good if not better, or allow you to perform at your best.

There are certainly good studies demonstrating the potential for improved endurance performance following carbohydrate loading, which may maximize liver and muscle glycogen storage. Other studies show it depends on factors such as race distance and the level of aerobic fitness. Still others are not so encouraging that carb loading is worth it. Unfortunately, most studies are performed on young, relatively healthy athletes and don’t consider potential consequences, e.g., health is not considered.

In addition, being athletic does not automatically confer better health as diet plays a key role — perhaps more than training. The result is that many athletes are fit but unhealthy.

If you wonder why you can’t perform as well as you once did, regardless of age, consider other scientific, clinically relevant, healthy options associated with lifestyle, especially reducing carbohydrates to tap into your potential fat stores. To personalize the many that are out there, go here.

6 Comments

  • JohnD says:

    Why are white potatoes “Unhealthy” but sweet potatoes “healthy”?

  • Simon Weir says:

    Perhaps there should be a new concept…down with carb loading, up with sleep loading!

  • Graham Seabrook says:

    G’day Phil, thanks for another great post. I’ve been using MAF HR training for about 2 years now and earlier this year completed Ultraman Australia. I really enjoy this method and continually working toward improving my dietary intake. I appreciate if you could provide a little more explanation as to why you list banana and watermelon as unhealthy carbs. Obviously if one was to over consume either of these fruits I see the issue, but to consume either home grown or organically grown banana’s or watermelons in moderation I don’t understand the problem. For example, through 9 mths training for the Ultraman my go to recovery drink I consumed approx’ 20 to 30 minutes post exercise was 250-300ml organic raw milk, 2 x organic raw eggs, 1 x organic medium banana with a dash or organic vanilla and 1/2 teaspoon raw honey blended. Thanks again for all the posts on great information. Cheers. Graham.

  • James says:

    How is honey considered a healthy carb? I know it supposedly contains some great compounds, but it is essentially sugar.

    • Hi James,

      Great question. Turns out that some of those great compounds help lower the glycemic index of honey, so it turns out to have a much milder effect than sugar in the body. So considering its positive properties, it is the kind of thing you DO want to eat if your level of carbohydrate tolerance allows for it.

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