A putative low-carbohydrate ketogenic diet elicits mild nutritional ketosis but does not impair the acute or chronic hypertrophic responses to resistance exercise in rodents

Exogenous Ketone Supplementation and Ketogenic Diets for Exercise: Considering the Effect on Skeletal Muscle Metabolism

In recent years, ketogenic diets and ketone supplements have increased in popularity, particularly as a mechanism to improve exercise performance by modifying energetics. Since the skeletal muscle is a major metabolic and locomotory organ, it is important to take it into consideration when considering the effect of a dietary intervention, and the impact of physical activity on the body. The goal of this review is to summarize what is currently known and what still needs to be investigated concerning the relationship between ketone body metabolism and exercise, specifically in the skeletal muscle. Overall, it is clear that increased exposure to ketone bodies in combination with exercise can modify skeletal muscle metabolism, but whether this effect is beneficial or detrimental remains unclear and needs to be further interrogated before ketogenic diets or exogenous ketone supplementation can be recommended.

Ketogenic Diet Combined with Moderate Aerobic Exercise Training Ameliorates White Adipose Tissue Mass, Serum Biomarkers, and Hepatic Lipid Metabolism in High-Fat Diet-Induced Obese Mice

Obesity is a serious public health issue worldwide. Growing evidence demonstrates the efficacy of the ketogenic diet (KD) for weight loss, but there may be some adverse side effects such as dyslipidemia and hepatic steatosis. Aerobic exercise is a widely recognized approach for improving these metabolic markers. Here we explored the combined impacts of KD and moderate aerobic exercise for an 8-week intervention on body weight and fat loss, serum biomarkers, and hepatic lipid metabolism in a mouse model of high-fat diet-induced obesity. Both KD and KD combined with exercise significantly reduced body weight and fat mass. No significant adverse effects of KD were observed in serum biomarkers or hepatic lipid storage, except for an increase in circulating triglyceride level. However, aerobic exercise lowered serum triglyceride levels, and further ameliorated serum parameters, and hepatic steatosis in KD-fed mice. Moreover, gene and protein expression analysis indicated that KD combined with exercise was associated with increased expression of lipolysis-related genes and protein levels, and reduced expression of lipogenic genes relative to KD without exercise. Overall, our findings for mice indicate that further work on humans might reveal that KD combined with moderate aerobic exercise could be a promising therapeutic strategy for obesity.

Dietary restriction in senolysis and prevention and treatment of disease

Aging represents a key risk factor for a plethora of diseases. Targeting detrimental processes which occur during aging, especially before onset of age-related disease, could provide drastic improvements in healthspan. There is increasing evidence that dietary restriction (DR), including caloric restriction, fasting, or fasting-mimicking diets, extend both lifespan and healthspan. This has sparked interest in the use of dietary regimens as a non-pharmacological means to slow aging and prevent disease. Here, we review the current evidence on the molecular mechanisms underlying DR-induced health improvements, including removal of senescent cells, metabolic reprogramming, and epigenetic rejuvenation.

Ketogenic diets slow melanoma growth in vivo regardless of tumor genetics and metabolic plasticity

Background

Growing evidence supports the use of low-carbohydrate/high-fat ketogenic diets as an adjunctive cancer therapy. However, it is unclear which genetic, metabolic, or immunological factors contribute to the beneficial effect of ketogenic diets. Therefore, we investigated the effect of ketogenic diets on the progression and metabolism of genetically and metabolically heterogeneous melanoma xenografts, as well as on the development of melanoma metastases in mice with a functional immune system.

Methods

Mice bearing BRAF mutant, NRAS mutant, and wild-type melanoma xenografts as well as mice bearing highly metastatic melanoma allografts were fed with a control diet or ketogenic diets, differing in their triglyceride composition, to evaluate the effect of ketogenic diets on tumor growth and metastasis. We performed an in-depth targeted metabolomics analysis in plasma and xenografts to elucidate potential antitumor mechanisms in vivo.

Results

We show that ketogenic diets effectively reduced tumor growth in immunocompromised mice bearing genetically and metabolically heterogeneous human melanoma xenografts. Furthermore, the ketogenic diets exerted a metastasis-reducing effect in the immunocompetent syngeneic melanoma mouse model. Targeted analysis of plasma and tumor metabolomes revealed that ketogenic diets induced distinct changes in amino acid metabolism. Interestingly, ketogenic diets reduced the levels of alpha-amino adipic acid, a biomarker of cancer, in circulation to levels observed in tumor-free mice. Additionally, alpha-amino adipic acid was reduced in xenografts by ketogenic diets. Moreover, the ketogenic diets increased sphingomyelin levels in plasma and the hydroxylation of sphingomyelins and acylcarnitines in tumors.

Conclusions

Ketogenic diets induced antitumor effects toward melanoma regardless of the tumors´ genetic background, its metabolic signature, and the host immune status. Moreover, ketogenic diets simultaneously affected multiple metabolic pathways to create an unfavorable environment for melanoma cell proliferation, supporting their potential as a complementary nutritional approach to melanoma therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-022-00288-7.

Ketone Body Metabolism in the Ischemic Heart

Ketone bodies have been identified as an important, alternative fuel source in heart failure. In addition, the use of ketone bodies as a fuel source has been suggested to be a potential ergogenic aid for endurance exercise performance. These findings have certainly renewed interest in the use of ketogenic diets and exogenous supplementation in an effort to improve overall health and disease. However, given the prevalence of ischemic heart disease and myocardial infarctions, these strategies may not be ideal for individuals with coronary artery disease. Although research studies have clearly defined changes in fatty acid and glucose metabolism during ischemia and reperfusion, the role of ketone body metabolism in the ischemic and reperfused myocardium is less clear. This review will provide an overview of ketone body metabolism, including the induction of ketosis via physiological or nutritional strategies. In addition, the contribution of ketone body metabolism in healthy and diseased states, with a particular emphasis on ischemia-reperfusion (I-R) injury will be discussed.

Effects of Ketogenic Dieting on Body Composition, Strength, Power, and Hormonal Profiles in Resistance Training Men

Wilson, JM, Lowery, RP, Roberts, MD, Sharp, MH, Joy, JM, Shields, KA, Partl, JM, Volek, JS, and D'Agostino, DP. Effects of ketogenic dieting on body composition, strength, power, and hormonal profiles in resistance training men. J Strength Cond Res 34(12): 3463-3474, 2020-This study investigated the impact of an isocaloric and isonitrogenous ketogenic diet (KD) versus a traditional western diet (WD) on changes in body composition, performance, blood lipids, and hormonal profiles in resistance-trained athletes. Twenty-five college-aged men were divided into a KD or traditional WD from weeks 1 to 10, with a reintroduction of carbohydrates from weeks 10 to 11, while participating in a resistance training program. Body composition, strength, power, and blood lipid profiles were determined at weeks 0, 10, and 11. A comprehensive metabolic panel and testosterone levels were also measured at weeks 0 and 11. Lean body mass (LBM) increased in both the KD and WD groups (2.4% and 4.4%, p < 0.01) at week 10. However, only the KD group showed an increase in LBM between weeks 10 and 11 (4.8%, p < 0.0001). Finally, fat mass decreased in both the KD (-2.2 ± 1.2 kg) and WD groups (-1.5 ± 1.6 kg). Strength and power increased to the same extent in the WD and KD conditions from weeks 1 to 11. No changes in any serum lipid measures occurred from weeks 1 to 10; however, a rapid reintroduction of carbohydrate from weeks 10 to 11 raised plasma triglyceride levels in the KD group. Total testosterone increased significantly from weeks 0 to 11 in the KD diet (118 ng·dl) as compared to the WD (-36 ng·dl) from pre to post while insulin did not change. The KD can be used in combination with resistance training to cause favorable changes in body composition, performance, and hormonal profiles in resistance-trained men.

Ketogenic diet in the treatment of cancer - Where do we stand?

BACKGROUND

Cancer is one of the greatest public health challenges worldwide, and we still lack complementary approaches to significantly enhance the efficacy of standard anticancer therapies. The ketogenic diet, a high-fat, low-carbohydrate diet with adequate amounts of protein, appears to sensitize most cancers to standard treatment by exploiting the reprogramed metabolism of cancer cells, making the diet a promising candidate as an adjuvant cancer therapy.

SCOPE OF REVIEW

To critically evaluate available preclinical and clinical evidence regarding the ketogenic diet in the context of cancer therapy. Furthermore, we highlight important mechanisms that could explain the potential antitumor effects of the ketogenic diet.

MAJOR CONCLUSIONS

The ketogenic diet probably creates an unfavorable metabolic environment for cancer cells and thus can be regarded as a promising adjuvant as a patient-specific multifactorial therapy. The majority of preclinical and several clinical studies argue for the use of the ketogenic diet in combination with standard therapies based on its potential to enhance the antitumor effects of classic chemo- and radiotherapy, its overall good safety and tolerability and increase in quality of life. However, to further elucidate the mechanisms of the ketogenic diet as a therapy and evaluate its application in clinical practice, more molecular studies as well as uniformly controlled clinical trials are needed.

Ergogenic Properties of Ketogenic Diets in Normal-Weight Individuals: A Systematic Review

Ketogenic diets (KDs) have received increasing attention among athletes and physically active individuals. However, the question as to whether and how the diet could benefit this healthy cohort remains unclear.Purpose: This study was designed to systematically review the existing evidence concerning the effect of KDs on body composition, aerobic and anaerobic capacity, muscle development, and sports performance in normal-weight individuals including athletes.Methods: A systematic search of English literature was conducted through electronic databases including PubMed, EBSCOhost, and Google Scholar. Upon the use of search criteria, 23 full-text original human studies involving non-obese participants were included in this review. For more stratified and focused analysis, these articles were further categorized based on the outcomes being examined including 1) body mass (BM) and %fat, 2) substrate utilization, 3) blood substrate and hormonal responses, 4) aerobic capacity and endurance performance, and 5) strength, power, and anaerobic capacity.Results: Our review indicates that a non-calorie-restricted KD carried out for ≥3 weeks can produce a modest reduction in BM and %fat, while maintaining fat-free mass. This diet leads to augmented use of fat as fuel, but this adaptation doesn't seem to improve endurance performance. Additionally, ad libitum KDs combined with resistance training will pose no harm to developing strength and power, especially when protein intake is increased modestly.Conclusions: It appears that a non-calorie-restricted KD provides minimal ergogenic benefits in normal-weight individuals including athletes, but can be used for optimizing BM and body composition without compromising aerobic and anaerobic performance. Key teaching pointsKetogenic diets have received increasing attention among athletes and physically active individuals.It remains elusive as to whether ketogenic diets could confer ergogenic benefits for those who are normal weight but want to use the diet to improve fitness and performance.An interesting dilemma exists in that ketogenic diets can reduce body mass and %fat and increase fat oxidation, but they can also decrease glycogen stores and limit sports performance.This review concludes that a non-calorie-restricted ketogenic diet provides minimal ergogenic benefits in normal-weight individuals, but can be used to optimize body mass and composition without compromising athletic performance.This finding can be important for esthetic or weight-sensitive athletes because the diet may allow them to reach a target body mass without having to sacrifice athletic performance.The ketogenic diet-induced metabolic adaptations require a state of ketosis, and thus caution should be taken because an excessive increase in ketone bodies can be detrimental to health.

The impact of keto-adaptation on exercise performance and the role of metabolic-regulating cytokines

The ketogenic diet (KD) is a normocaloric diet composed of high-fat, low-carbohydrate, and adequate protein that induces fasting-like effects and results in the production of ketone bodies. Initially used widely for children with refractory epilepsy, the KD gained popularity due to its beneficial effects on weight loss, diabetes, and cancer. In recent years, there has been a resurgence in interest surrounding the KD and exercise performance. This review provides new insights into the adaptation period necessary for enhancement in skeletal muscle fat and ketone oxidation after sustained nutritional ketosis. In addition, this review highlights metabolically active growth factors and cytokines, which may function as important regulators of keto-adaptation in the setting of exercise and the KD.

Ketogenic Diet and Skeletal Muscle Hypertrophy: A Frenemy Relationship?

Ketogenic diet (KD) is a nutritional regimen characterized by a high-fat and an adequate protein content and a very low carbohydrate level (less than 20 g per day or 5% of total daily energy intake). The insufficient level of carbohydrates forces the body to primarily use fat instead of sugar as a fuel source. Due to its characteristic, KD has often been used to treat metabolic disorders, obesity, cardiovascular disease, and type 2 diabetes. Skeletal muscle constitutes 40% of total body mass and is one of the major sites of glucose disposal. KD is a well-defined approach to induce weight loss, with its role in muscle adaptation and muscle hypertrophy less understood. Considering this lack of knowledge, the aim of this review was to examine the scientific evidence about the effects of KD on muscle hypertrophy. We first described the mechanisms of muscle hypertrophy per se, and secondly, we discussed the characteristics and the metabolic function of KD. Ultimately, we provided the potential mechanism that could explain the influence of KD on skeletal muscle hypertrophy.

Nutritional Ketosis for Weight Management and Reversal of Metabolic Syndrome

PURPOSE OF REVIEW

The goal of this paper is to review current literature on nutritional ketosis within the context of weight management and metabolic syndrome, namely, insulin resistance, lipid profile, cardiovascular disease risk, and development of non-alcoholic fatty liver disease. We provide background on the mechanism of ketogenesis and describe nutritional ketosis.

RECENT FINDINGS

Nutritional ketosis has been found to improve metabolic and inflammatory markers, including lipids, HbA1c, high-sensitivity CRP, fasting insulin and glucose levels, and aid in weight management. We discuss these findings and elaborate on potential mechanisms of ketones for promoting weight loss, decreasing hunger, and increasing satiety. Humans have evolved with the capacity for metabolic flexibility and the ability to use ketones for fuel. During states of low dietary carbohydrate intake, insulin levels remain low and ketogenesis takes place. These conditions promote breakdown of excess fat stores, sparing of lean muscle, and improvement in insulin sensitivity.

Benefits of resistance training on body composition and glucose clearance are inhibited by long-term low carbohydrate diet in rats

Background/Objectives

Regular exercise training is effective to altering many markers of metabolic syndrome and its effects are strongly influenced by the type of consumed diet. Nowadays, resistance training (RT) has been frequently associated with low-carbohydrate high-fat diet (LCD). After long term these diets causes body weight (BW) regain with deleterious effects on body composition and metabolic risk factors. The effects of RT associated with long-term LCD on these parameters remain unexplored. We aimed to investigate the effects of RT when associated with long-term LCD on BW, feed efficiency, body composition, glucose homeostasis, liver parameters and serum biochemical parameters during BW regain period in rats.

Subjects/Methods

Male Sprague–Dawley rats were fed with LCD (LC groups) or standard diet (STD) (ST groups). After 10 weeks-diet animals were separated into sedentary (Sed-LC and Sed-ST) and resistance-trained (RT-LC and RT-ST) groups (N = 8/group). RT groups performed an 11-week climbing program on a ladder with progressive load. Dual x-ray absorptiometry, glucose tolerance tests and insulin tolerance tests were performed at weeks 10 and 20. Liver and serum were collected at week 21.

Results

RT reduced feed efficiency, BW gain, liver fat and total and LDL cholesterol, and improved body composition and glucose clearance in animals fed on STD. In those fed with LCD, RT reduced caloric intake, BW regain, liver fat and serum triglycerides levels. However, improvement in body composition was inhibited and bone mineral density and glucose clearance was further impaired in this association.

Conclusions

The LCD nullifies the beneficial effects of RT on body composition, glucose homeostasis and impairs some health parameters. Our results do not support the association of RT with LCD in a long term period.

Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial

BACKGROUND

Ketogenic diets (KD) have become a popular method of promoting weight loss. More recently, some have recommended that athletes adhere to ketogenic diets in order to optimize changes in body composition during training. This study evaluated the efficacy of an 8-week ketogenic diet (KD) during energy surplus and resistance training (RT) protocol on body composition in trained men.

METHODS

Twenty-four healthy men (age 30 ± 4.7 years; weight 76.7 ± 8.2 kg; height 174.3 ± 19.7 cm) performed an 8-week RT program. Participants were randomly assigned to a KD group (n = 9), non-KD group (n = 10, NKD), and control group (n = 5, CG) in hyperenergetic condition. Body composition changes were measured by dual energy X-ray absorptiometry (DXA). Compliance with the ketosis state was monitored by measuring urinary ketones weekly. Data were analyzed using a univariate, multivariate and repeated measures general linear model (GLM) statistics.

RESULTS

There was a significant reduction in fat mass (mean change, 95% CI; p-value; Cohen's d effect size [ES]; - 0.8 [- 1.6, - 0.1] kg; p < 0.05; ES = - 0.46) and visceral adipose tissue (- 96.5 [- 159.0, - 34.0] g; p < 0.05; ES = - 0.84), while no significant changes were observed in the NKD and CG in fat mass (- 0,5 [- 1.2, 0.3] kg; p > 0.05; ES = - 0.17 and - 0,5 [- 2.4, 1.3] kg; p > 0.05; ES = - 0.12, respectively) or visceral adipose tissue (- 33.8 [- 90.4, 22.8]; p > 0.5; ES = - 0.17 and 1.7 [- 133.3, 136.7]; p > 0.05; ES = 0.01, respectively). No significant increases were observed in total body weight (- 0.9 [- 2.3, 0.6]; p > 0.05; ES = [- 0.18]) and muscle mass (- 0.1 [- 1.1,1.0]; p > 0,05; ES = - 0.04) in the KD group, but the NKD group showed increases in these parameters (0.9 [0.3, 1.5] kg; p < 0.05; ES = 0.18 and (1.3[0.5, 2.2] kg; p < 0,05; ES = 0.31, respectively). There were no changes neither in total body weight nor lean body mass (0.3 [- 1.2, 1.9]; p > 0.05; ES = 0.05 and 0.8 [- 0.4, 2.1]; p > 0.05; ES = 0.26, respectively) in the CG.

CONCLUSION

Our results suggest that a KD might be an alternative dietary approach to decrease fat mass and visceral adipose tissue without decreasing lean body mass; however, it might not be useful to increase muscle mass during positive energy balance in men undergoing RT for 8 weeks.

Physiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders to Resistance Exercise Training: Current Perspectives and Future Research Directions

Numerous reports suggest there are low and high skeletal muscle hypertrophic responders following weeks to months of structured resistance exercise training (referred to as low and high responders herein). Specifically, divergent alterations in muscle fiber cross sectional area (fCSA), vastus lateralis thickness, and whole body lean tissue mass have been shown to occur in high versus low responders. Differential responses in ribosome biogenesis and subsequent protein synthetic rates during training seemingly explain some of this individual variation in humans, and mechanistic in vitro and rodent studies provide further evidence that ribosome biogenesis is critical for muscle hypertrophy. High responders may experience a greater increase in satellite cell proliferation during training versus low responders. This phenomenon could serve to maintain an adequate myonuclear domain size or assist in extracellular remodeling to support myofiber growth. High responders may also express a muscle microRNA profile during training that enhances insulin-like growth factor-1 (IGF-1) mRNA expression, although more studies are needed to better validate this mechanism. Higher intramuscular androgen receptor protein content has been reported in high versus low responders following training, and this mechanism may enhance the hypertrophic effects of testosterone during training. While high responders likely possess “good genetics,” such evidence has been confined to single gene candidates which typically share marginal variance with hypertrophic outcomes following training (e.g., different myostatin and IGF-1 alleles). Limited evidence also suggests pre-training muscle fiber type composition and self-reported dietary habits (e.g., calorie and protein intake) do not differ between high versus low responders. Only a handful of studies have examined muscle biomarkers that are differentially expressed between low versus high responders. Thus, other molecular and physiological variables which could potentially affect the skeletal muscle hypertrophic response to resistance exercise training are also discussed including rDNA copy number, extracellular matrix and connective tissue properties, the inflammatory response to training, and mitochondrial as well as vascular characteristics.

Long-term resistance exercise-induced muscular hypertrophy is associated with autophagy modulation in rats

Elevation of anabolism and concurrent suppression of catabolism are critical metabolic adaptations for muscular hypertrophy in response to resistance exercise (RE). Here, we investigated if RE-induced muscular hypertrophy is acquired by modulating a critical catabolic process autophagy. Male Wistar Hannover rats (14 weeks old) were randomly assigned to either sedentary control (SC, n = 10) or resistance exercise (RE, n = 10). RE elicited significant hypertrophy of flexor digitorum profundus (FDP) muscles in parallel with enhancement in anabolic signaling pathways (phosphorylation of AKT, mTOR, and p70S6K). Importantly, RE-treated FDP muscle exhibited a significant decline in autophagy evidenced by diminished phosphorylation levels of AMPK, a decrease in LC3-II/LC3-I ratio, an increase in p62 level, and a decline in active form of lysosomal protease CATHEPSIN L in the absence of alterations of key autophagy proteins: ULK1 phosphorylation, BECLIN1, and BNIP3. Our study suggests that RE-induced hypertrophy is achieved by potentiating anabolism and restricting autophagy-induced catabolism.

The Three-Month Effects of a Ketogenic Diet on Body Composition, Blood Parameters, and Performance Metrics in CrossFit Trainees: A Pilot Study

Adopting low carbohydrate, ketogenic diets remains a controversial issue for individuals who resistance train given that this form of dieting has been speculated to reduce skeletal muscle glycogen levels and stifle muscle anabolism. We sought to characterize the effects of a 12-week ketogenic diet (KD) on body composition, metabolic, and performance parameters in participants who trained recreationally at a local CrossFit facility. Twelve participants (nine males and three females, 31 ± 2 years of age, 80.3 ± 5.1 kg body mass, 22.9 ± 2.3% body fat, 1.37 back squat: body mass ratio) were divided into a control group (CTL; n = 5) and a KD group (n = 7). KD participants were given dietary guidelines to follow over 12 weeks while CTL participants were instructed to continue their normal diet throughout the study, and all participants continued their CrossFit training routine for 12 weeks. Pre, 2.5-week, and 12-week anaerobic performance tests were conducted, and pre- and 12-week tests were performed for body composition using dual X-ray absorptiometry (DXA) and ultrasound, resting energy expenditure (REE), blood-serum health markers, and aerobic capacity. Additionally, blood beta hydroxybutyrate (BHB) levels were measured weekly. Blood BHB levels were 2.8- to 9.5-fold higher in KD versus CTL throughout confirming a state of nutritional ketosis. DXA fat mass decreased by 12.4% in KD (p = 0.053). DXA total lean body mass changes were not different between groups, although DXA dual-leg lean mass decreased in the KD group by 1.4% (p = 0.068), and vastus lateralis thickness values decreased in the KD group by ~8% (p = 0.065). Changes in fasting glucose, HDL cholesterol, and triglycerides were similar between groups, although LDL cholesterol increased ~35% in KD (p = 0.048). Between-group changes in REE, one-repetition maximum (1-RM) back squat, 400 m run times, and VO_2peak were similar between groups. While our n-sizes were limited, these preliminary data suggest that adopting a ketogenic diet causes marked reductions in whole-body adiposity while not impacting performance measures in recreationally-trained CrossFit trainees. Whether decrements in dual-leg muscle mass and vastus lateralis thickness in KD participants were due to fluid shifts remain unresolved, and increased LDL-C in these individuals warrants further investigation.

The 1-Week and 8-Month Effects of a Ketogenic Diet or Ketone Salt Supplementation on Multi-Organ Markers of Oxidative Stress and Mitochondrial Function in Rats

We determined the short- and long-term effects of a ketogenic diet (KD) or ketone salt (KS) supplementation on multi-organ oxidative stress and mitochondrial markers. For short-term feedings, 4 month-old male rats were provided isocaloric amounts of KD (n = 10), standard chow (SC) (n = 10) or SC + KS (~1.2 g/day, n = 10). For long-term feedings, 4 month-old male rats were provided KD (n = 8), SC (n = 7) or SC + KS (n = 7) for 8 months and rotarod tested every 2 months. Blood, brain (whole cortex), liver and gastrocnemius muscle were harvested from all rats for biochemical analyses. Additionally, mitochondria from the brain, muscle and liver tissue of long-term-fed rats were analyzed for mitochondrial quantity (maximal citrate synthase activity), quality (state 3 and 4 respiration) and reactive oxygen species (ROS) assays. Liver antioxidant capacity trended higher in short-term KD- and SC + KS-fed versus SC-fed rats, and short-term KD-fed rats exhibited significantly greater serum ketones compared to SC + KS-fed rats indicating that the diet (not KS supplementation) induced ketonemia. In long term-fed rats: (a) serum ketones were significantly greater in KD- versus SC- and SC + KS-fed rats; (b) liver antioxidant capacity and glutathione peroxidase protein was significantly greater in KD- versus SC-fed rats, respectively, while liver protein carbonyls were lowest in KD-fed rats; and (c) gastrocnemius mitochondrial ROS production was significantly greater in KD-fed rats versus other groups, and this paralleled lower mitochondrial glutathione levels. Additionally, the gastrocnemius pyruvate-malate mitochondrial respiratory control ratio was significantly impaired in long-term KD-fed rats, and gastrocnemius mitochondrial quantity was lowest in these animals. Rotarod performance was greatest in KD-fed rats versus all other groups at 2, 4 and 8 months, although there was a significant age-related decline in performance existed in KD-fed rats which was not evident in the other two groups. In conclusion, short- and long-term KD improves select markers of liver oxidative stress compared to SC feeding, although long-term KD feeding may negatively affect skeletal muscle mitochondrial physiology.

A Ketogenic Diet Extends Longevity and Healthspan in Adult Mice

Calorie restriction, without malnutrition, has been shown to increase lifespan and is associated with a shift away from glycolysis toward beta-oxidation. The objective of this study was to mimic this metabolic shift using low-carbohydrate diets and to determine the influence of these diets on longevity and healthspan in mice. C57BL/6 mice were assigned to a ketogenic, low-carbohydrate, or control diet at 12 months of age and were either allowed to live their natural lifespan or tested for physiological function after 1 or 14 months of dietary intervention. The ketogenic diet (KD) significantly increased median lifespan and survival compared to controls. In aged mice, only those consuming a KD displayed preservation of physiological function. The KD increased protein acetylation levels and regulated mTORC1 signaling in a tissue-dependent manner. This study demonstrates that a KD extends longevity and healthspan in mice.

A ketogenic diet supplemented with medium-chain triglycerides enhances the anti-tumor and anti-angiogenic efficacy of chemotherapy on neuroblastoma xenografts in a CD1-nu mouse model

Neuroblastoma (NB) is a pediatric malignancy characterized by a marked reduction in aerobic energy metabolism. Recent preclinical data indicate that targeting this metabolic phenotype by a ketogenic diet (KD), especially in combination with calorie restriction, slows tumor growth and enhances metronomic cyclophosphamide (CP) therapy of NB xenografts. Because calorie restriction would be contraindicated in most cancer patients, the aim of the present study was to optimize the KD such that the tumors are sensitized to CP without the need of calorie restriction. In a NB xenograft model, metronomic CP was combined with KDs of different triglyceride compositions and fed to CD1-nu mice ad libitum. Metronomic CP in combination with a KD containing 8-carbon medium-chain triglycerides exerted a robust anti-tumor effect, suppressing growth and causing a significant reduction of tumor blood-vessel density and intratumoral hemorrhage, accompanied by activation of AMP-activated protein kinase in NB cells. Furthermore, the KDs caused a significant reduction in the serum levels of essential amino acids, but increased those of serine, glutamine and glycine. Our data suggest that targeting energy metabolism by a modified KD may be considered as part of a multimodal treatment regimen to improve the efficacy of classic anti-NB therapy.

Low-Carbohydrate-High-Fat Diet: Can it Help Exercise Performance?

Low-carbohydrate-high-fat (LCHF) diets have been used as a means of weight loss and control of symptoms in several clinical conditions. There is emerging evidence that the metabolic changes induced by LCHF diets enhance endurance performance. The aims of this review are to examine the evidence of LCHF diets in improving various aspects of athletic performance. Long-term LCHF dietary intake may help control body weight and fat mass while maintaining lean body mass in athletes in weight-sensitive sports. LCHF-adapted endurance athletes can reach the maximal fat oxidation rate of approximately 1.5 g/min, with a lower carbohydrate oxidation rate and similar muscle glycogen content and a resynthesis rate compared to their counterparts consuming high-carbohydrate-low-fat (HCLF) diets. The elevated fat oxidation rate and glycogen sparing effect may improve performance in ultra-endurance events. These metabolic changes may also prevent the decline in performance in later stages of repeated high-intensity movements, in which the aerobic metabolism becomes more important. However, elevated blood concentrations of non-esterified fatty acids and ammonia during exercise after LCHF diets may lead to early development of central fatigue. It appears that at least several months of adaptation to a LCHF diet are required for the metabolic changes and restoration of muscle glycogen to occur. Further investigations on LCHF diets are needed regarding (1) performance after weight loss in weight-categorized sports; (2) repeated high-intensity exercise performance; (3) development of central fatigue during endurance events; (4) perceptual-motor performance during prolonged intermittent sports; and (5) ideal dietary fatty acid compositions.

Carbohydrate intake and resistance-based exercise: are current recommendations reflective of actual need?

Substantial research has been completed examining the impact of carbohydrate (CHO) intake on endurance exercise, whereas its role in resistance-based exercise performance, adaptation and cell signalling has yet to be fully characterised. This empirical shortcoming has precluded the ability to establish specific CHO recommendations for resistance exercise. This results in recommendations largely stemming from findings based on endurance exercise and/or anecdotal evidence despite the distinct energetic demands and molecular responses mediating adaptation from endurance- and resistance-based exercise. Moreover, the topic of CHO and exercise has become one of polarising nature with divergent views - some substantiated, others lacking evidence. Current literature suggests a moderately high daily CHO intake (3-7 g/kg per d) for resistance training, which is thought to prevent glycogen depletion and facilitate performance and adaptation. However, contemporary investigation, along with an emerging understanding of the molecular underpinnings of resistance exercise adaptation, may suggest that such an intake may not be necessary. In addition to the low likelihood of true glycogen depletion occurring in response to resistance exercise, a diet restrictive in CHO may not be detrimental to acute resistance exercise performance or the cellular signalling activity responsible for adaptation, even when muscle glycogen stores are reduced. Current evidence suggests that signalling of the mammalian target of rapamycin complex 1, the key regulatory kinase for gene translation (protein synthesis), is unaffected by CHO restriction or low muscular glycogen concentrations. Such findings may call into question the current view and subsequent recommendations of CHO intake with regard to resistance-based exercise.

A Ketogenic Diet in Rodents Elicits Improved Mitochondrial Adaptations in Response to Resistance Exercise Training Compared to an Isocaloric Western Diet

Purpose: Ketogenic diets (KD) can facilitate weight loss, but their effects on skeletal muscle remain equivocal. In this experiment we investigated the effects of two diets on skeletal muscle mitochondrial coupling, mitochondrial complex activity, markers of oxidative stress, and gene expression in sedentary and resistance exercised rats. Methods: Male Sprague-Dawley rats (9-10 weeks of age, 300-325 g) were fed isocaloric amounts of either a KD (17 g/day, 5.2 kcal/g, 20.2% protein, 10.3% CHO, 69.5% fat, n = 16) or a Western diet (WD) (20 g/day, 4.5 kcal/g, 15.2% protein, 42.7% CHO, 42.0% fat, n = 16) for 6 weeks. During these 6 weeks animals were either sedentary (SED, n = 8 per diet group) or voluntarily exercised using resistance-loaded running wheels (EXE, n = 8 per diet group). Gastrocnemius was excised and used for mitochondrial isolation and biochemical analyses. Results: In the presence of a complex II substrate, the respiratory control ratio (RCR) of isolated gastrocnemius mitochondria was higher (p < 0.05) in animals fed the KD compared to animals fed the WD. Complex I and IV enzyme activity was higher (p < 0.05) in EXE animals regardless of diet. SOD2 protein levels and GLUT4 and PGC1α mRNA expression were higher (p < 0.05) in EXE animals regardless of diet. Conclusion: Our data indicate that skeletal muscle mitochondrial coupling of complex II substrates is more efficient in chronically resistance trained rodents fed a KD. These findings may provide merit for further investigation, perhaps on humans.

Whey protein-derived exosomes increase protein synthesis and hypertrophy in C2-C12 myotubes

We sought to examine potential amino acid independent mechanisms whereby hydrolyzed whey protein (WP) affects muscle protein synthesis (MPS) and anabolism in vitro. Specifically, we tested (1) whether 3-h and 6-h treatments of WP, essential amino acids, or l-leucine (Leu) affected MPS, and whether 6-h treatments with low-, medium-, or high doses of WP versus Leu affected MPS; (2) whether knockdown of the primary Leu transporter affected WP- and Leu-mediated changes in MPS, mammalian target of rapamycin (mTOR) signaling responses, or both, following 6-h treatments; (3) whether exosomes isolated from WP (WP-EXO) affected MPS, mTOR signaling responses, or both, compared with untreated (control) myotubes, following 6-h, 12-h, and 24-h treatments, and whether they affected myotube diameter following 24-h and 48-h treatments. For all treatments, 7-d post-differentiated C₂C₁₂ myotubes were examined. In experiment 1, 6-h WP treatments increased MPS compared with control (+46%), Leu (+24%), and essential amino acids (+25%). Moreover, the 6-h low-, medium-, and high WP treatments increased MPS by approximately 40 to 50% more than corresponding Leu treatments. In experiment 2 (LAT short hairpin RNA-transfected myotubes), 6-h WP treatments increased MPS compared with control (+18%) and Leu (+19%). In experiment 3, WP-EXO treatments increased MPS over controls at 12h (+18%) and 24h (+45%), and myotube diameters increased with 24-h (+24%) and 48-h (+40%) WP-EXO treatments compared with controls. The WP-EXO treatments did not appear to operate through mTOR signaling; instead, they increased mRNA and protein levels o eukaryotic initiation factor 4A. Bovine-specific microRNA following 24-h WP-EXO treatments were enriched in myotubes (chiefly miR-149-3p, miR-2881), but were not related to hypertrophic gene targets. To summarize, hydrolyzed WP-EXO increased skeletal MPS and anabolism in vitro, and this may be related to an unknown mechanism that increases translation initiation factors rather than enhancing mTOR signaling or the involvement of bovine-specific microRNA.

Effects of a ketogenic diet on adipose tissue, liver, and serum biomarkers in sedentary rats and rats that exercised via resisted voluntary wheel running

We investigated the effects of different diets on adipose tissue, liver, serum morphology, and biomarkers in rats that voluntarily exercised. Male Sprague-Dawley rats (∼9-10 wk of age) exercised with resistance-loaded voluntary running wheels (EX; wheels loaded with 20-60% body mass) or remained sedentary (SED) over 6 wk. EX and SED rats were provided isocaloric amounts of either a ketogenic diet (KD; 20.2%-10.3%-69.5% protein-carbohydrate-fat), a Western diet (WD; 15.2%-42.7-42.0%), or standard chow (SC; 24.0%-58.0%-18.0%); n = 8-10 in each diet for SED and EX rats. Following the intervention, body mass and feed efficiency were lowest in KD rats, independent of exercise (P < 0.05). Absolute and relative (body mass-adjusted) omental adipose tissue (OMAT) masses were greatest in WD rats (P < 0.05), and OMAT adipocyte diameters were lowest in KD-fed rats (P < 0.05). None of the assayed OMAT or subcutaneous (SQ) protein markers were affected by the diets [total acetyl coA carboxylase (ACC), CD36, and CEBPα or phosphorylated NF-κB/p65, AMPKα, and hormone-sensitive lipase (HSL)], although EX unexpectedly altered some OMAT markers (i.e., higher ACC and phosphorylated NF-κB/p65, and lower phosphorylated AMPKα and phosphorylated HSL). Liver triglycerides were greatest in WD rats (P < 0.05), and liver phosphorylated NF-κB/p65 was lowest in KD rats (P < 0.05). Serum insulin, glucose, triglycerides, and total cholesterol were greater in WD and/or SC rats compared with KD rats (P < 0.05), and serum β-hydroxybutyrate was greater in KD vs. SC rats (P < 0.05). In conclusion, KD rats presented a healthier metabolic profile, albeit the employed exercise protocol minimally impacts any potentiating effects that KD has on fat loss.