The Low Carb and ketogenic diets for sports and bodybuilding

In addition to nutritionists, you'll have noticed that "Low Carb mania" is increasingly spreading to gyms. Some bodybuilders, and not the least, practice this diet regularly, or at least take care to moderate their food intake. carbohydratesThis is particularly true on days when they're not training. In this chapter, we'll look at the benefits of such a diet and whether it's really applicable to athletes.


LCHF reminder

As we mentioned earlier, the Low Carb Hight Fat (LCHF) diet is a type of diet that consists of reducing carbohydrate intake and preferring a higher intake of lipids (fats) as a source of energy, while moderating its intake of proteins. This diet allows the human body to use fats as an energy source rather than carbohydrates.

According to aficionados of this diet, LCHF has several advantages, including being healthier because it's closer to our ancestral metabolism, and it's an excellent way to burn fat, since too much carbohydrate can indirectly lead to fat storage and therefore weight gain.

This diet would therefore be particularly suitable for people wishing to lose a few extra kilos, as well as for those curious to try a new type of diet that is more "ancestral" and less stressful on the metabolism. The question remains as regards sportsmen and women, particularly body-builders on the one hand, and endurance sports enthusiasts on the other.

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Fitness and bodybuilding: is Low Carb right for you?

Dry and low-carb

According to the experts in this field, LCHF helps athletes to lose fat more easily, and can also be used during a lean period. This seems logical, since with a diet too rich in sugar, your pancreas will produce insulin to regulate the excessive level of glucose in the blood. And to burn this sugar, insulin will produce fat, which will be stored. When carbohydrate intake falls, insulin levels drop again, and our body draws on existing fat to make energy, leading to a de facto slimming of the body.

A low-carb diet will therefore enable our bodies to produce less insulin and fat, and thus draw energy directly from reserves. A phenomenon which, for bodybuilders, is conducive to leaner, more defined muscles.


Low-carb and muscle gain

If the Low-Carb High Fat is a fat-loss diet, but is it effective for building muscle? It's a debate that continues to divide bodybuilding circles. Indeed, some believe that you can't run two hares at once, and that without carbohydrate intake, you don't generate the necessary insulin levels to promote the creation of muscle tissue. Conversely, others point to their own experience, which seems to confirm that LCHF is not at all incompatible with muscle volume gain.

To answer this question, let's take a look at what science tells us.

An initial study dating from 2012 is without appeal:

Significant reduction in body weight and body fat after dieting ketogenic (VLCKD) versus a Western diet (WD). Stationary force.

The experiment conducted concluded that "despite the concerns of coaches and doctors about the possible adverse effects of low-carbohydrate diets on sports performance, and the well-known importance of carbohydrates, there are no data showing a decrease in strength after a ketogenic diet." And the study adds that "the use of a ketogenic diet over 30 days can reduce body weight and body fat without having negative effects on muscle performance in high-level athletes", in this case gymnasts.


Low Carb / Ketogenic and endurance sports

If an LCHF diet doesn't lead to significant muscle loss, is it still suitable for an endurance event, which requires a lot of energy over time? According to several scientific studies, for example this oneThe LCHF diet would not affect sporting performance in endurance events, as keto-adapted athletes would have given their bodies time to "switch" fuels, replacing carbohydrates with fats as an energy source.

Another study from 2018 also claims that a low-carb ketogenic diet reduces body mass without compromising the performance of Olympic weightlifters.

However, other medical sources indicate that LCHF is not the most suitable food for athletes taking part in high-intensity ultra-endurance events. For example, a 2017 study concludes that a low-carbohydrate, high-fat diet reduces performance (-1.6%) in race walking, compared with a high-carbohydrate diet (+5.3%), for a 10km endurance run.

If we combine the results of all the scientific studies carried out on this subject, the following trends would seem to emerge:

  • The ketogenic diet may significantly impair performance in high-intensity and endurance sports.
  • On the other hand, it does not seem to induce any difference in performance for low- to medium-intensity sports, as well as for strength and body-building events.


Conclusion about sport and a low-carb diet

If we bring together the various scientific data available on the Internet, we can conclude that a ketogenic diet in the strict sense of the term, i.e. with less than 50 grams/day, is not really recommended for sports, unless accompanied by health professionals.

On the other hand, its softer version, the low-carb diet, can be adopted in parallel with sport, especially if frequent carbohydrate rebounds are practiced.

Secondly, as each case is unique, the low-carb diet is particularly suited to people who "fatten up" a lot despite their efforts during the lean period. The low-carb diet will enable them to avoid the cravings associated with a greedy diet, and encourage their bodies to burn fat, while still benefiting from a reasonable intake of carbohydrates for their protective nutrients and minerals.

It's a question of adapting your diet, and not depriving yourself of the "right" carbohydrates, if you want to benefit from the energy needed for sporting effort and to develop your muscle tissue.

Finally, regardless of this type of diet, standard nutritional recommendations for bodybuilders are based on a carbohydrate intake of around 3 to 6 grams of carbohydrate per kilo of body weight, which works out at between 210 and 420g per day for a 70-kilo athlete.

However, Western eating habits lead women and men to consume as much, if not more, carbohydrates per day, without necessarily practicing sports at the same timeor at least not on a daily basis. In other words, most sedentary people consume as much, if not more, carbohydrate every day than regular athletes.

This leads us to conclude that a low-carb diet is ultimately "low" only in comparison with our current eating habits, which are heavily oriented towards the consumption of carbohydrates and sugars, whether slow or fast.


Are there athletes who follow the LCHF and ketogenic diets?

The low-carb diet has its followers in the world of sport and bodybuilding. Some are low-carb only, while others - rarer still - are advocates of the strict ketogenic diet.

There are also those who do it only over a given period, once a year, to reset their insulin sensitivity, while others do it before a competition to dry out before a carbohydrate rebound on the eve of an event or photo shoot.

Finally, some bodybuilders moderate their carbohydrate intake every week, then do what they call a "carbohydrate recharge", i.e. one or more relatively higher carbohydrate meals over one or two days, to replenish their muscles with glycogen. This practice is sometimes coupled with the "cheat meal", which consists of "indulging" in food without paying attention to macronutrient distribution or calorie intake.

It's up to you to find your "formula".

The Blooness guide

This article is part the Blooness food guide, a summary of which can be found here. By reading this guide, you'll learn how to master the way you eat, so you can get fitter and healthier.

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