Keto Diet: Friend Or Foe To Muscle Mass?

The ketogenic diet is a popular weight-loss strategy, but it has been linked to muscle loss and bone loss. The diet involves reducing carbohydrate and protein intake while increasing fat intake, which can lead to a lack of essential nutrients and a higher risk of injury. To avoid muscle loss, it is important to consume enough protein, not completely eliminate carbohydrates, get enough calories, and incorporate strength training into your exercise routine. While the keto diet can be effective for weight loss, it may not be the best choice for athletes or those looking to build muscle.

Ketogenic diets may cause muscle shrinkage and bone loss

Michael Greger, M.D. FACLM, notes that a ketogenic diet may blunt the performance of endurance athletes and their strength training. He cites a study in which participants performed eight weeks of standard upper and lower body training protocols, such as bench presses, pull-ups, squats, and deadlifts. Those randomized to a non-ketogenic diet added about three pounds of muscle mass, whereas those on a keto diet lost muscle mass by about 3.5 ounces on average.

Bone fractures, slowed growth, and kidney stones are among the side effects that disproportionately affect children on keto diets. Ketogenic diets may cause a steady rate of bone loss as measured in the spine, presumed to be because ketones are acidic, so keto diets can put people in what’s called a “chronic acidotic state”. Case reports of children on keto diets include a nine-year-old girl who developed osteoporosis, bone fractures, kidney stones, and then pancreatitis, which can be triggered by having too much fat in the blood.

A 2018 study found that individuals on a keto diet for three months lost the same amount of body fat and had similar muscle changes as those on regular diets. However, some of those on the keto diet experienced more muscle loss in their legs.

Ketosis may undermine exercise efforts in non-athletes

Ketogenic diets have been found to undermine exercise efforts and lead to muscle shrinkage and bone loss. An official position paper from the International Society of Sports Nutrition noted the "ergolytic effect" of keto diets on both high- and low-intensity workouts. Ergolytic is the opposite of ergogenic, which means performance-boosting. For non-athletes, ketosis may also undermine exercise efforts.

Increased Feelings of Fatigue and Mood Disturbance

Ketosis has been correlated with increased feelings of "perceived exercise effort" and "also significantly correlated to feelings of 'fatigue' and to 'total mood disturbance' during physical activity. These data suggest that the ability and desire to maintain sustained exercise might be adversely impacted in individuals adhering to ketogenic diets for weight loss.

Shrinkage of Measured Muscle Mass

CrossFit trainees have reported shrinkage of measured muscle mass on a ketogenic diet, so eating patterns may not only blunt performance but also strength training. When individuals performed two months of standard upper and lower body training protocols, such as squats and pull-ups, those randomized to a non-ketogenic diet added about three pounds of muscle mass, whereas those on a keto diet tended to subtract muscle mass by an average of about 3.5 ounces. Bodybuilding on a keto diet has been called an "oxymoron" even by advocates of that eating pattern.

Bone Fractures, Slowed Growth, and Kidney Stones

Bone fractures, slowed growth, and kidney stones are among the side effects that disproportionately plague children on keto diets. Ketogenic diets may cause a steady rate of bone loss as measured in the spine, presumed to be because ketones are acidic, so keto diets can put people in what’s called a "chronic acidotic state."

Keto diets may not be suitable for athletes or those looking to build muscle

Keto diets have become popular among endurance athletes as a performance enhancer. The diet prescribes a significant reduction in carbohydrate intake, which facilitates physiological changes that promote the utilization of ketones. However, there is some evidence that keto diets may not be suitable for athletes or those looking to build muscle.

Performance in Athletes

Firstly, it is important to note that there is limited research on the effects of keto diets on athletic performance, with only a few published studies examining the impact on maximal oxygen uptake and other outcomes such as time to exhaustion, race time, rating of perceived exertion, and peak power. The available evidence suggests that the effects of keto diets on athletic performance are mixed, with some studies reporting improvements and others reporting no significant changes or even decreases in performance.

One hypothesis for the variation in performance outcomes among studies is the heterogeneity across training/recovery protocols and fitness levels of the athletes. For example, studies that have shown improvements in performance among endurance athletes have tended to examine the effects of keto diets in professional athletes with high base levels of aerobic capacity, a factor that has been associated with faster recovery times and greater positive adaptations to training. These studies have also explicitly included a recovery protocol in their training prescription, which could have influenced the athletes' training outcomes.

In contrast, athletes involved in high-intensity, short-duration sports might see drops in performance while on a keto diet. A small study found that people on a keto diet performed more poorly at anaerobic exercise tasks than those eating more carbs, with their performance being 4 to 15 percent lower than the high-carb group. Another study found that keto diets were associated with increased feelings of "perceived exercise effort" and "fatigue" during physical activity, which could negatively impact the ability to maintain sustained exercise.

Muscle Growth

Keto diets may also not be ideal for those looking to build muscle. This is because keto diets restrict protein intake, which is essential for building muscle. Skimping on protein intake can have unwanted and unhealthy results. In addition, keto diets can lead to muscle shrinkage and bone loss. One study found that participants who followed a keto diet and performed weight training actually lost muscle mass, while those on a non-keto diet gained muscle mass.

Overall Health

Finally, keto diets may have negative effects on overall health. For example, keto diets have been linked to an increased risk of bone fractures, slowed growth, and kidney stones, especially in children. Keto diets can also impair artery function and increase the risk of heart disease.

In conclusion, while keto diets may provide some benefits for endurance athletes, there is also evidence that they may negatively impact performance, particularly in high-intensity, short-duration sports. Additionally, keto diets may not be ideal for those looking to build muscle due to the restricted protein intake and the potential for muscle shrinkage and bone loss. Therefore, it is important for individuals to carefully consider the potential risks and benefits of a keto diet before deciding to adopt this dietary approach.

The keto diet may not be sustainable for bodybuilders

The keto diet is a popular way to lose weight, but it may not be the best choice for bodybuilders looking to build and maintain muscle. The diet involves drastically reducing carbohydrate intake and increasing fat intake, which can lead to a state of ketosis where the body burns fat for energy instead of glucose. While this can be effective for weight loss, there are some concerns about its impact on muscle mass.

Firstly, the keto diet can lead to muscle loss, especially if protein intake is limited. Muscle is made up of protein, and when the body doesn't get enough from the diet, it can break down muscle tissue to fuel activity. This can be mitigated by ensuring adequate protein intake, but the keto diet's restriction on protein means that bodybuilders may not be able to consume enough to support muscle growth fully.

Secondly, the keto diet may not provide enough calories to support the energy demands of intense bodybuilding workouts. Bodybuilders need a surplus of calories to build muscle, but the keto diet's focus on fat and restriction of carbohydrates can make it challenging to consume enough calories. This could lead to fatigue, loss of strength, and reduced stamina, hindering a bodybuilder's performance and ability to build muscle.

Additionally, the keto diet can be challenging to stick to due to its restrictive nature. It requires eliminating many food groups, including processed foods, sugars, grains, and even some vegetables and fruits. This can make it difficult to get all the necessary nutrients and may not be sustainable for bodybuilders in the long term.

Furthermore, the keto diet may not be optimal for female bodybuilders. A study found that while the keto diet helped burn fat, it was less effective in increasing lean body mass in women. Female bodybuilders may find that a higher-carb style of eating, such as carb cycling or targeted keto, is more effective for building muscle.

Finally, the keto diet has been found to undermine exercise efforts and lead to muscle shrinkage and bone loss. An official position paper from the International Society of Sports Nutrition noted the "ergolytic effect" of keto diets on both high- and low-intensity workouts, meaning it impaired performance rather than enhanced it. This suggests that the keto diet may not be the best choice for bodybuilders looking to optimise their training and maximise muscle growth.

In conclusion, while the keto diet may be effective for weight loss, it may not be sustainable or optimal for bodybuilders. The restriction on protein and calories can lead to muscle loss and fatigue, and the diet's challenging nature may make it difficult to stick to in the long term. Bodybuilders should carefully consider the potential benefits and drawbacks before deciding if the keto diet is suitable for their specific goals and needs.

Keto may be suitable for short-term cutting phases

The ketogenic diet is a popular eating plan that involves a person consuming a high amount of fat (60 to 80 percent of calories) and very low carbohydrates, starting with 20 to 30 grams per day. This shift in diet forces the body to use fat for energy instead of carbohydrates, a state called ketosis. While the keto diet can lead to quick weight loss, it is not a long-term solution and may not be suitable for everyone.

Firstly, keto can help you lose weight fast. When the body is deprived of carbohydrates, it turns to stored body fat as an alternative energy source, leading to rapid weight loss. This state of ketosis can also blunt hunger, making it easier to stick to the diet and achieve weight loss goals.

Secondly, keto can enhance muscle definition. Very low-carbohydrate diets have a diuretic effect, which reduces water retention and increases muscle definition. Additionally, the level of circulating growth hormone is increased, aiding in fat loss and muscle building.

Thirdly, keto can be a strategic tool for athletes and bodybuilders who want to increase muscle mass while reducing subcutaneous fat. While it is challenging to achieve both goals simultaneously, a meticulously planned keto approach can yield rapid results.

However, it is important to note that keto is not recommended as a permanent dietary solution. Some experts suggest that short-term bouts of 6-10 weeks are ideal for achieving cutting goals. Additionally, the restricted amount of protein on the keto diet can lead to muscle loss, especially when strength training is involved. Therefore, it is crucial to ensure adequate protein intake and incorporate the right type and amount of strength training into your exercise routine.

In conclusion, while keto may be suitable for short-term cutting phases, it should be approached with caution and tailored to individual needs. It is always advisable to consult with a healthcare professional before starting any new diet, especially one as restrictive as keto.

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