High-Carb vs. Low-Carb – Which Is the Better Diet?

Dear BLOG readers, Dear PEAK customers,

Things are really heating up in the fitness scene. In the past, there were clear trends that constantly alternated. Driven by relevant events—such as new dietary guidelines from the German Nutrition Society (DGE) or U.S. institutions, or a new book by a nutrition guru like the well-known Dr. Atkins—athletes followed either low-fat, low-carb, or ketogenic (i.e., zero-carb) diets.

Today, things are different. Anyone who considers themselves someone today takes a specific side and either swears by large amounts of carbohydrates or avoids them altogether. You could almost start to think that Mother Nature played a trick on us when she gave us three macronutrients, as if to say, “Three is one too many.” Today, I’m asking the critical question: Why? What’s the point of all this? Do we really have to pin the blame on one macronutrient and avoid it? If so, which one?

Who comes out on top in the high-carb vs. low-carb battle?

A very interesting article awaits you!

Enjoy!

Low-Carb Is “Healthier”

The first important step toward answering the initial question is to ask: What purpose is it meant to serve? Often, proponents of a particular diet cite studies that highlight supposed health benefits—which is perfectly fine, as long as the focus is primarily on that objective and, consequently, on the relevant target groups.

Weight Loss and Cardiovascular Markers

If you’re looking for a diet that helps overweight or even obese people lose weight and improve cardiovascular markers, I don’t think there’s any doubt about it. In the reference list, I’ve included more than 20 individual citations, all of whose results point in the direction now outlined. So if you need more than just clear evidence, scroll down. The 2012 meta-analysis by Hu et al. provides a good overview, encompassing a total of 23 studies conducted between 1966 and 2011 and involving 2,788 participants. It concluded that low-carb diets are at least as effective as low-fat diets in terms of weight loss and improving metabolic markers. Also of interest in this context is the study by Fostet et al., which followed 307 overweight participants over two years and found that both low-carb and low-fat diets show promising results in terms of weight loss. However, when it comes to risk markers for cardiovascular disease, low-carb diets came out on top in the long-term study. Researchers at Johns Hopkins Medicine also note that there are no issues regarding vascular health arising from a low-carb diet. They further state that the ability to reduce inflammation is neither compromised nor limited by a diet rich in protein and fat during weight loss.

In 2004, Volek et al. demonstrated that, in a short-term trial, low-carb diets result in significantly greater fat loss compared to low-fat diets. This effect was also studied in overweight participants, and it was more pronounced in men than in women. In 2004, Yancy and colleagues conducted a comparison of ketogenic versus high-carb diets in 120 overweight individuals with elevated blood lipid levels. The results showed that the very-low-carb group experienced greater weight loss, lower serum triglyceride levels, and higher HDL cholesterol levels compared to the high-carb group.

Also of interest in this context is the study by Simone Jacobs et al., who compared the development of diabetes in 4,221 participants over a 10-year period and concluded that a higher intake of carbohydrates was associated with increased production of palmitic and stearic acids in the liver from carbohydrates. The increased formation of new fat from carbohydrates in the liver represents a major risk factor for diabetes, which is why the researchers recommend cutting back on carbohydrates rather than on fat. 

Diabetes Treatment

Low-carbohydrate diets also have the edge for those with existing diabetes or prediabetes. Schwingshackl et al. clearly summarized this in their 2014 meta-analysis, which included a total of 14 studies and 1,753 participants. In the groups with lower carbohydrate intake, significantly better levels of triglycerides, diastolic blood pressure, and HDL cholesterol were observed.

Mood and Cognitive Function

Cheatham et al. compared the administration of high-glycemic and low-glycemic carbohydrates to 42 overweight participants in terms of mood and cognitive function and found that a diet rich in high-glycemic carbohydrates neither improves nor impairs cognitive performance but has a negative effect on the so-called POMS scale, which subjectively reflects the participants’ well-being.

Conclusion

When it comes to determining a winner in terms of “healthy” nutrition, there is no doubt. The body of research supporting low-carb and opposing high-carb diets is overwhelming and unequivocally favors a diet that uses carbohydrates sparingly, both in short-term and long-term studies. Although weight loss occurs with both dietary approaches, low-carb diets allow for significantly better maintenance and regulation of other health parameters.

Is low-carb also the better alternative for athletes?

The Basic Concept

Now that we’ve sufficiently addressed objective one, we’ve also covered the majority of all studies conducted for this comparison. All the characteristics and benefits mentioned are extremely promising, but they miss the mark when it comes to choosing the right diet for athletes. We must consider, on the one hand, that we are not obese, and on the other hand, that athletes in most cases pursue performance goals in addition to purely weight-oriented ones. Performance—and, in our scene, muscle preservation in particular—can thus be cited as new goals for which we’re willing to push ourselves hard several times a week at the gym, on the street, or wherever else. This so-called physical activity naturally brings a completely different energy requirement into play, and this is precisely where the question arises of how an athlete can—and wants to—sustainably adopt a low-carb diet as a nutritional strategy. Pure strength training, CrossFit, contact sports, team sports, and even endurance sports over shorter distances have one thing in common—they take place primarily in an anaerobic metabolic state. Pure endurance sports over longer distances metabolize a proportionally higher amount of calories from fat than from carbohydrates. Even here, however, more glucose is inevitably utilized than in inactive or only slightly active non-athletes. Depending on the metabolic demands and individual fat metabolism (which can be specifically trained to conserve glycogen), more carbohydrates are utilized one way or another during athletic activity. Any athlete who adheres to the typical low-carb guidelines—which (as mentioned above) were designed for obese individuals who are largely inactive or only moderately active—is therefore, in all likelihood, eating in a way that falls outside their individual needs. But let’s take another close look at what studies on this topic actually say.

Performance

As early as 1997, a study by Langfort et al. examined the effects of a low-carb diet (5% of daily calories from carbohydrates) during a submaximal exercise test and found that it significantly impaired anaerobic work capacity. The presumed causes are, of course, reduced muscle glycogen stores and a reduced rate of glycolysis; however, a consistently elevated activity of the sympathetic nervous system (both after exercise and at rest) was also observed.

In the *Journal of Applied Physiology*, Havemann et al. published a very interesting study that also compared low-carb and high-carb diets in athletes. The unique aspect: As part of the low-carb diet, an attempt was made to maintain higher fat oxidation for 6 days and to train fat metabolism. On day 7, a carbohydrate-loading day was scheduled, intended to positively affect muscle glycogen stores and thus prevent a decline in performance. The plan only partially worked. In the low-carb group, fat oxidation was indeed increased during a 100-kilometer run that included several 1-kilometer sprints. Overall, the high-carb group was only (or at least) 3 minutes and 44 seconds faster than the low-carb group over 100 kilometers. This was due to declining performance in the low-carb group during the aforementioned sprints.

The Food and Agriculture Organization of the United States also clearly advocates for carbohydrates during physical exertion in its statement titled “The Role of Carbohydrates in Exercise and Physical Performance.” As early as 1988, Brewer et al. noted in their study that increasing dietary carbohydrates (regardless of the glycemic load) can promote rapid recovery of endurance performance following exercise to the point of exhaustion.

Of course, there are also less conclusive studies, such as Erlenbusch’s 2005 meta-analysis, which—after reviewing 20 studies on diet and endurance performance—could not identify a clear winner due to the heterogeneity of the results. The test protocols in these studies were too varied to allow for a uniform conclusion.

Positive findings regarding the use of high-fat, low-carbohydrate diets for endurance athletes can also be found, for example, in the 2015 study by Volek et al. For this strategy to be successful, however, a series of metabolic adaptations must first take place, which must be specifically trained through an adapted low-carbohydrate diet under exercise conditions. This is known as “keto adaptation.” As early as 1983, Phinney et al. described such a relationship in connection with even a ketogenic diet (fewer than 20 g of carbohydrates per day). Over a four-week period, this had no performance-reducing effect on trained endurance athletes. In 2002, Rowlands et al. found that, compared to a high-carbohydrate diet, a low-carbohydrate diet in cycling leads to lower insulin levels before exercise and higher plasma glucose levels during exercise, increased lipolysis, and increased fat oxidation—which the researchers suggest could even positively influence performance in ultra-distance disciplines.

Finally, the Department of Human Nutrition, Foods, and Exercise in Virginia provides compelling and well-documented evidence on how glycogen depletion occurs during sprints or resistance training. The researchers cite several sources demonstrating that during a typical resistance training session, muscle glycogen stores in the trained muscles are depleted by only 25 to 40%. The rate of depletion appears to be significantly higher during sprints. Here, Hargreaves et al. report glycogen depletion of around 47% for just two 30-second intervals. It’s no wonder, then, that the results from studies on the various disciplines are inconsistent. For glycogen-intensive activities such as sprints, a high-carb diet appears to be beneficial, whereas these same benefits cannot be clearly demonstrated for resistance training. This study also provides initial evidence that a “high-carb diet” offers no additional advantage compared to a moderate-carb diet.

Conclusion

After reviewing numerous different studies, there appears to be no clear answer to the question of whether a low-carb diet is suitable for optimal performance. It is relatively clear that metabolism adapts strongly to the respective dietary situation and, in the case of a low-carb diet, upregulates both lipolysis and fat oxidation. This is certainly beneficial in terms of body composition, but as far as performance is concerned, it only comes into play—if at all—once sufficient adaptation in the sense of “keto adaptation” has taken place.

High-intensity sports will be able to achieve better performance with slightly more carbohydrates in the diet and may also recover more quickly. As we have seen, strength training does NOT fall into this category, since the depletion of muscle glycogen is far less than many people think. From this perspective, no significant improvements in performance are to be expected from high amounts of carbohydrates in this context. Ultimately, it seems obvious and essential to optimize carbohydrate intake based on individual performance needs.

For strength athletes, a middle ground between low-carb and high-carb diets could be the optimal strategy for maximizing performance on the one hand and optimizing body composition on the other.

Muscle Preservation

The second important aspect for athletes revolves around preserving what we painstakingly build up over months and years: metabolically active muscle mass. Of course, bodybuilders want to minimize their body fat percentage, but if this comes at the expense of muscle mass, then the actual goal is missed. This raises the question of to what extent a low-carb strategy is suitable—as part of a weight-loss diet—for athletes who are interested not only in losing body fat but also in maximizing muscle mass retention.

An important piece of the puzzle here is, of course, protein intake. Numerous studies, such as those by Garthe et al., Mero et al., Mettler et al., Stiegler et al., and Elia et al., provide compelling evidence that increasing protein intake while in a caloric deficit helps preserve lean body mass. According to Hall et al. and Elia et al., there is also a correlation between protein requirements and body fat percentage. The less body fat, the more protein is needed to preserve lean body mass. The situation with carbohydrates is somewhat less clear-cut. Phillips et al., for example, show that reducing carbohydrate intake while simultaneously increasing the proportion of protein in the diet increases fat oxidation and helps preserve lean body mass. According to Garthe et al. and Mettler et al., a diet that is at least moderate in protein and carbohydrates is still suitable for preventing a decline in performance and excessive loss of lean body mass. Ultimately, Lambert et al. show that even low insulin levels correlate with a loss of lean body mass, which is why consuming an adequate amount of carbohydrates is recommended here as well.

Conclusion

To improve fat oxidation, carbohydrate intake must be both well-timed and reduced. However, when it comes to muscle preservation, a low-carb diet becomes less and less suitable as body fat percentage decreases. A moderate-carb diet, which provides the appropriate amount of carbohydrates depending on the situation, appears to be the best approach here.

High-Carb vs. Low-Carb – The Winner Is Moderate-Carb

After considering all the necessary factors, a relatively clear conclusion can be drawn. There is no universally valid winner in the high-carb vs. low-carb battle! Once again, it all comes down to one small word that has already gained the upper hand in numerous topics concerning sports nutrition and will continue to dominate: INDIVIDUALITY.

If I’m a non-athlete looking to lose weight, there’s simply no better option for me than a classic low-carb diet. As an athlete, however, it depends on what my goal is and how carbohydrate-intensive my sport is. My needs and goals determine the necessary amount of carbohydrates and, consequently, the nutritional approach—which, however, will rarely be low-carb.

To answer the question of how many carbohydrates are needed, we can refer to some findings from the study by Asker E. Jeukendrup. He examined the different effects of high-carb diets versus high-fat diets in relation to their use in endurance sports. According to his findings, five factors determined the actual carbohydrate requirement

1. Exercise intensity
2. Duration of exercise
3. Training status of fat metabolism
4. Dietary composition
5. Carbohydrate intake before and during training

Depending on the exercise intensity, the dominance of the energy substrate being metabolized changes. At around 65% VO2max, energy production shifts from a predominantly aerobic to a predominantly anaerobic supply, resulting in greater reliance on carbohydrates. Depending on the duration of exercise, energy production shifts increasingly toward fat metabolism as the exercise period lengthens. Depending on one’s training status, it is possible to maintain fat burning as the dominant energy source for a longer period of time and thus conserve glycogen. This can be particularly beneficial in endurance sports. With regard to diet, we have seen ample evidence that a low-carbohydrate diet places a greater demand on lipolysis and fat oxidation than on carbohydrate metabolism. In their 2000 study, Coyle et al. clearly demonstrate that a significant effect in this regard also depends on the specific meal consumed before training.

Jeukendrup identifies specific health concerns with both extreme dietary approaches—that is, high-fat and high-carb diets. In 1992, Mensink and Katan stated that high-carb diets carry the risk of raising triglyceride levels and lowering HDL cholesterol levels over time. In 1996, Hokanson and Austin argued that high-carb diets are associated with an increased risk of coronary heart disease, a finding that Patsch et al. expanded upon in 1992 to include an increased risk of atherosclerosis. To date, no definitive findings are available regarding the long-term effects of high-fat diets. Possible effects include elevated triglyceride levels and associated insulin resistance, though these have not yet been demonstrated in short-term studies.

The bottom line is that, for both performance and optimal body composition, there is a key factor to consider regarding carbohydrate intake: available glycogen stores. These consist of a muscular component (250–400 g), a hepatic component (100–115 g), and a very small amount in the blood. According to Jeudenkamp, it is sufficient to keep these stores replenished to perform at an optimal level. Well-maintained glycogen stores delay the onset of fatigue, prolong the duration of exercise at a steady state, and improve performance. Consuming MORE carbohydrates does NOT provide additional benefits but does increase cardiovascular risk.

Summary

THE TIME FOR THE MODERATE-CARB DIET HAS COME

… in other words, this article provides relatively comprehensive support for what I’ve been sharing with all athletes for more than a year as part of my HBN (Human Based Nutrition) nutrition concept and what I’ve been trying to convey. The question of high-carb versus low-carb is just as irrelevant for athletes as the question of which of the three macronutrients is the real villain—because THERE ISN’T ONE.

• We need to stop blaming a specific macronutrient for health problems.
• We need to stop comparing ourselves to sedentary people.
• We need to stop comparing ourselves to one another.
• We need to stop mixing up different types of exercise.
• Strength athletes need to stop thinking they consume massive amounts of carbohydrates—they don’t!
• Endurance athletes need to stop completely derailing their fat metabolism by consuming massive amounts of carbohydrates during training.

Ultimately, everyone will get the best results by viewing themselves as individuals and tailoring their diet accordingly! In the vast majority of cases, the result will be neither “high-carb” nor “low-carb” as we know them, but rather a diet that includes all three macronutrients in a more or less balanced—but in any case, needs-optimized—distribution.

Best regards

Holger Gugg

www.body-coaches.de

Read also...

• What Really Happens to Our Metabolism When We’re on a Diet?
• Konjac Flour—An Effective Diet Aid?

Image source: _italo_ from Fotolia.com

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