Are Carbs Evil?


“Why did God kick Adam and Eve out of the garden for eating the apple?”

Because apples contain carbs, and carbs are evil.”

This is a great nutrition joke and it rings so true with some of the zealot-like attitudes that are rife in the field. This article focuses on a couple of areas where we have been conned into a certain way of thinking about carbohydrates, often a simplistic, absolute non-truth, and where the actual proof lies on the matter. This couldn’t really be a better time to write this article, as it seems we are currently going through a period of heightened awareness of carbohydrates, and perhaps seeing some shifts with regard to how we view them. For many years now the mantra for health, weight loss and performance has been that runners should be eating a low fat, high carbohydrate diet. It became clear early on that this dogmatic approach didn’t tell the whole story, but rather than the opposing view bringing about a more balanced approach, the pendulum is swinging to the other side. Low carb, high fat diets for health, weight loss and performance! Let’s take a look at some of these extreme views and what the evidence has to say on them.

on a scale
Reducing carbohydrates for many is a good way to reduce calories without drastically lowering the nutrient density of the diet.

The carbohydrate weight loss con

Weight loss is probably the area where the “common knowledge” has changed to the greatest extent with regard to carbohydrate, perhaps due to the hugely successful Atkins Diet movement and copycat diets by any other name. Because the advice to follow a high carbohydrate diet failed so miserably, it only stands to reason that a low carbohydrate diet must be the answer! Wrong again. While low carbohydrate diets do seem to fare better in the short term, in the long term people simply don’t seem to stick to them. Also, more often than not the lower carb approach leads to a higher protein intake and if there’s any macronutrient really worth paying attention to during weight loss, it is protein.

For sustainable weight loss, people need not vilify carbs (or fat for that matter) but instead focus on a method that allows them to maintain a lower calorie intake. Yes, you read that right, calories DO matter!

It doesn’t matter what the latest and greatest diet book is telling you, this is an unequivocal fact. This, however, isn’t to say that all you should focus on is calories or that the mantra “just eat less and exercise more” is a good one. Reducing carbohydrates for many is a good way to reduce calories without drastically lowering the nutrient density of the diet. For example, reducing the amount of rice and pasta you eat, along with sugary junk food, won’t significantly impact your intake of minerals and vitamins or protein. That being said, a little higher carbohydrate, calorie reduced diet, so long as protein levels are maintained at appropriate levels, could be equally effective in the long term if it fits you. For the people who still believe that the “unrefined carbohydrates can do no wrong” recent control trials have proven that the recommendation to eat more whole fruit and vegetables doesn’t result in weight loss in overweight people. In fact, in those who are already overweight, this can result in weight GAIN. Even lean people advised to eat more fruit and vegetables can gain weight if they consume this in liquid and not in the whole form. Again, this simply shows us that calories do matter when it comes to changing bodyweight and it’s well advised not to demonize carbs or, conversely, put them on a pedestal either.

woman with headband
What we do know about health is that, as humans, we are very versatile and can thrive on a large range of carbohydrate intakes.

The carbohydrate health con

The carbohydrate health con is probably the biggest and longest existing nutrition myth in the world, and is maybe the one with the greatest controversy surrounding it. Carbohydrates (including sugar) are cheap to produce and profitable to sell, which makes guidelines on carbohydrate a matter of economics and politics as well as health. Early guidelines might have been well meant and innocent but modifications based on new knowledge are where the controversies now lie. Ever since dietary guidelines were first introduced we’ve been told to aim for a healthy diet low in fat, high in carbohydrate and low in protein. This way of thinking has become so entrenched that even those with cancer and diabetes are encouraged to eat these very same high glycemic load diets as though there’s much evidence that they’re in some way therapeutic, which of course isn’t the case. This myth still persists even though there’s a lot of positive publicity around the Mediterranean diet, which is rich in high fat foods, even foods with a fairly high content of the dreaded saturated fat such as olive oil (>13% saturated fat).

So what’s the truth? Well, it’s difficult to say anything different from what was said for carbohydrates and weight loss – there isn’t the evidence available to vilify one macronutrient. Nevertheless, since we know that being obese is a serious risk factor in many diseases such as the before mentioned cancer and diabetes, and we also know that we’re less restrained with foods we believe to be healthier (known as the ‘health halo effect’), which may result in excessive energy intake, could it be that by putting carbohydrates on a pedestal it led to unintended effects on food consumption and patterns of excess weight and obesity? In nutrition, the mantra “first do no harm” seems to have lost a foothold and opinions and observations are given far too much value before proper evidence is available. What we do know about health is that, as humans, we are very versatile and can thrive on a large range of carbohydrate intakes.

Taking a closer look at optimal health through diet especially for runners, we see some fairly interesting things. Studies that have examined increased carbohydrate and reduced fat intakes to the very bottom of the supposedly healthy range (15% of total calories) in both female and male runners have shown adverse effects on risk factors for cardiovascular disease! What’s fortunate in this situation is that anyone running for cardiovascular benefits will be doing much more good than any of these possible negative effects. Nevertheless, if you are running for health, it would seem clever to compliment this by deciding for more moderate intakes of carbohydrate (and therefore fat).

Lastly, it would be remiss not to mention some of the myths that are coming out of the backlash against sugar and carbs. It has become almost common knowledge that consuming too much sugar (or carbohydrate) causes diabetes when in reality this is hugely misleading. Sugar isn’t “cause and effect” bad for the body and our “tolerance” for sugar can be increased, interestingly enough by partaking in some running! While consuming sugar should never be actively promoted, the frenzy around sugar has wrongly led to people questioning if eating a piece of fruit or pot of natural yogurt is good for their body. Rather than concentrating on these minute details it’s much better to look at your personal goals and the bigger picture, and adjust your sugar intake accordingly.

running woman
You definitely have to do some sessions with carbohydrate otherwise the body can lose its ability to use carbohydrate correctly.

The carbohydrate performance con

Every runner has undoubtedly heard of the advantages of carbohydrate loading prior to a race day. This idea of eating more carbohydrate to maximize the stores inside the muscles and thus prolong training performance has extensive evidence supporting its effectiveness. Nonetheless, issues have arisen by this information being applied across the board to all race distances and training sessions. Dozens of coaches have sworn by doing training sessions in a fairly carbohydrate restricted state; they might not have had a fancy word for it but morning fasted runs, for example, have been an integral part of their training strategy. Today we have the data to show that regular exercising in a completely carbohydrate fueled state may actually hinder some of the adaptations to training. For example, by exercising either fasted or just on a protein-based breakfast, the adaptations by the body to that training session are increased. Or you can complete one session with a carbohydrate meal beforehand and not consume any carbs in the meal afterward and then do another session later that day.

What’s essential is that you don’t end up always exercising or, even worse, competing on low carbohydrate. You definitely have to do some sessions with carbohydrate otherwise the body can lose its ability to use carbohydrate correctly; sounds like an old wives’ tale, but the physiological proof is there. Experts recommend that every runner should try this out because there’s no doubt the idea of “train low (carbohydrate), compete high (carbohydrate)” will be making the health media headlines for the next couple of years.

It also needs to be understood that when it comes to performance, we have to take into account the intensity and duration of the event. This will influence both the level of carbohydrate needed in the normal diet and if any carbohydrate in the form of drinks and gels needs to be consumed during the run.

Not long ago, a very interesting research review was carried out that looked at the advantages of carbohydrate intake during exercise when situations mimicked real life: e.g. subjects were allowed to eat breakfast beforehand instead of being fasted. The outcomes of this review were telling to say the least. Carbohydrates consumed during performance were said to have an “…unlikely effect with bouts up to maybe 70 minutes, and a potential but not compelling ergogenic effect with performance durations longer than about 70 minutes.” For sure, if your event or, even more so, training session lasts less than 70 minutes it’s unlikely you need to be worrying about gels and sports drinks.

As mentioned in the weight loss section, carbs usually aren’t uniquely fattening, therefore this isn’t a reason for avoidance. Some people may find, and research seems to support this, that a lower carbohydrate diet significantly improves their performance in very long endurance events. A considerable amount of other studies show that there’s merely no difference between low carb and high carb, which would allow for the individual to dictate their intake based on preference. Nonetheless, those competing in high performance events searching for an evidence-based approach to breaking their PB in the marathon would be best to use a higher carbohydrate content of their diet as a starting point to work from.

To conclude, it’s safe to say that next time you see an extreme headline on carbohydrates, whether it’s positive or negative, it’s likely to be misleading or downright wrong. If you don’t want to be conned again, find two to three people or sources of nutrition information that you trust and bounce them off each other. And keep in mind that there are very few absolutes when it comes to nutrition.

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Written by Camille Bennett

Camille Bennett is our nutrition expert interested in fitness diet and doesn’t run out of delicious ideas for healthy and nutritional meals.


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