Effects of a 15-Day Low Carbohydrate, High-Fat Diet in Resistance-Trained Men

International society of sports nutrition position stand: ketogenic diets

POSITION STATEMENT

The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the use of a ketogenic diet in healthy exercising adults, with a focus on exercise performance and body composition. However, this review does not address the use of exogenous ketone supplements. The following points summarize the position of the ISSN.

1. A ketogenic diet induces a state of nutritional ketosis, which is generally defined as serum ketone levels above 0.5 mM. While many factors can impact what amount of daily carbohydrate intake will result in these levels, a broad guideline is a daily dietary carbohydrate intake of less than 50 grams per day.

2. Nutritional ketosis achieved through carbohydrate restriction and a high dietary fat intake is not intrinsically harmful and should not be confused with ketoacidosis, a life-threatening condition most commonly seen in clinical populations and metabolic dysregulation.

3. A ketogenic diet has largely neutral or detrimental effects on athletic performance compared to a diet higher in carbohydrates and lower in fat, despite achieving significantly elevated levels of fat oxidation during exercise (~1.5 g/min).

4. The endurance effects of a ketogenic diet may be influenced by both training status and duration of the dietary intervention, but further research is necessary to elucidate these possibilities. All studies involving elite athletes showed a performance decrement from a ketogenic diet, all lasting six weeks or less. Of the two studies lasting more than six weeks, only one reported a statistically significant benefit of a ketogenic diet.

5. A ketogenic diet tends to have similar effects on maximal strength or strength gains from a resistance training program compared to a diet higher in carbohydrates. However, a minority of studies show superior effects of non-ketogenic comparators.

6. When compared to a diet higher in carbohydrates and lower in fat, a ketogenic diet may cause greater losses in body weight, fat mass, and fat-free mass, but may also heighten losses of lean tissue. However, this is likely due to differences in calorie and protein intake, as well as shifts in fluid balance.

7. There is insufficient evidence to determine if a ketogenic diet affects males and females differently. However, there is a strong mechanistic basis for sex differences to exist in response to a ketogenic diet.

eHealth usage among Chinese college students: qualitative findings

BACKGROUND

The information technology has developed rapidly with the evolution of internet environment transformed from requiring computer skills for information searching to self-managing health data and applying information. Therefore, a more diverse range of eHealth skills is required and these skills are referred as eHealth literacy. However, most eHealth literacy studies focused mainly on information searching skills. Little is known about eHealth usage behaviors of college students in this day and age.

OBJECTIVES

This study aimed to investigate how Chinese college students engage with eHealth tools and to determine the elements of their eHealth literacy.

METHODS

A purposive sample of 18 Chinese college students was recruited for in-depth interviews. Interviewees included three males and three females of each city (Beijing, Wuhan and Putian) from sports, medical, and non-health-related majors. Conventional content analysis was applied for data analysis.

RESULTS

The eHealth usage of different-major-students were compared and profiled by three themes of Expectance, Usage pattern and Perception. In Expectances, non-health major students applied eHealth only for urgent health need, sport major students used it to monitor health while medical major students, as frequent users for searching health database. In Usage pattern, purposes of eHealth for personal, practical and theoretical were identified for non-health major, sport major and medical major groups, respectively. In Perceptions, sport students felt more curious about eHealth than the other groups who perceived either fear (non-health students) or skeptical (medical students). By compiling those themes, the whole picture of eHealth usage was emerged. Based on that, the current study identified the related skills using the trilogy of Web 1.0 to 3.0, and derived a conceptual framework for eHealth literacy in the present day.

CONCLUSIONS

The current study obtained a comprehensive understanding of eHealth usage and a framework of eHealth literacy required for Chinese college students. And it gives a clearer look at web 3.0 related eHealth behaviors.

Lean mass sparing in resistance-trained athletes during caloric restriction: the role of resistance training volume

Many sports employ caloric restriction (CR) to reduce athletes’ body mass. During these phases, resistance training (RT) volume is often reduced to accommodate recovery demands. Since RT volume is a well-known anabolic stimulus, this review investigates whether a higher training volume helps to spare lean mass during CR. A total of 15 studies met inclusion criteria. The extracted data allowed calculation of total tonnage lifted (repetitions × sets × intensity load) or weekly sets per muscle group for only 4 of the 15 studies, with RT volume being highly dependent on the examined muscle group as well as weekly training frequency per muscle group. Studies involving high RT volume programs (≥ 10 weekly sets per muscle group) revealed low-to-no (mostly female) lean mass loss. Additionally, studies increasing RT volume during CR over time appeared to demonstrate no-to-low lean mass loss when compared to studies reducing RT volume. Since data regarding RT variables applied were incomplete in most of the included studies, evidence is insufficient to conclude that a higher RT volume is better suited to spare lean mass during CR, although data seem to favor higher volumes in female athletes during CR. Moreover, the data appear to suggest that increasing RT volume during CR over time might be more effective in ameliorating CR-induced atrophy in both male and female resistance-trained athletes when compared to studies reducing RT volume. The effects of CR on lean mass sparing seem to be mediated by training experience, pre-diet volume, and energy deficit, with, on average, women tending to spare more lean mass than men. Potential explanatory mechanisms for enhanced lean mass sparing include a preserved endocrine milieu as well as heightened anabolic signaling.

Paleolithic Diet-Effect on the Health Status and Performance of Athletes?

The aim of this meta-analysis was to review the impact of a Paleolithic diet (PD) on selected health indicators (body composition, lipid profile, blood pressure, and carbohydrate metabolism) in the short and long term of nutrition intervention in healthy and unhealthy adults. A systematic review of randomized controlled trials of 21 full-text original human studies was conducted. Both the PD and a variety of healthy diets (control diets (CDs)) caused reduction in anthropometric parameters, both in the short and long term. For many indicators, such as weight (body mass (BM)), body mass index (BMI), and waist circumference (WC), impact was stronger and especially found in the short term. All diets caused a decrease in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG), albeit the impact of PD was stronger. Among long-term studies, only PD cased a decline in TC and LDL-C. Impact on blood pressure was observed mainly in the short term. PD caused a decrease in fasting plasma (fP) glucose, fP insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) and glycated hemoglobin (HbA1c) in the short run, contrary to CD. In the long term, only PD caused a decrease in fP glucose and fP insulin. Lower positive impact of PD on performance was observed in the group without exercise. Positive effects of the PD on health and the lack of experiments among professional athletes require longer-term interventions to determine the effect of the Paleo diet on athletic performance.

The metabolic and performance effects of carbohydrate timing in resistance trained males undergoing a carbohydrate restricted diet

The purpose of this investigation was to examine the importance of carbohydrate (CHO) timing while consuming a carbohydrate restricted diet (CRD) and completing a high-intensity exercise program. Eighteen males completed 6 weeks of training with the first 2 weeks serving as familiarization. During the final 4 weeks, subjects were randomized into 2 groups and completed 3 days of resistance training and 2 days of high-intensity interval training, while consuming a CRD (∼25%, ∼25%, and ∼50%, CHO, protein, and fat, respectively). The supplemented group (n = 9) ingested 30 g of CHO during exercise and 40 g of CHO immediately after each training session. The non-supplemented group (n = 9) consumed a non-caloric placebo during exercise. Pre- and post-testing measures included back squat and bench press 1-repetition maximums (1-RM), peak oxygen consumption (V̇O_2peak), anaerobic power, body composition, fasted glucose, insulin, and total testosterone. Both groups significantly improved back squat and bench press 1-RM, V̇O_2peak, and power output (p < 0.05), but there were no differences in blood markers or body composition. Our data suggests that CHO timing does not negatively impact training adaptations during a high-intensity exercise regimen when dietary CHO intake is restricted, but that favorable adaptations can be made while consuming a CRD. Novelty: Carbohydrate restricted dieting has no negative impact on resistance training adaptations. Short-term high-intensity interval training is effective in increasing peak oxygen consumption.

A 3-Week, Low-Carbohydrate, High-Fat Diet Improves Multiple Serum Inflammatory Markers in Endurance-Trained Males

Waldman, HS, Heatherly, AJ, Killen, LG, Hollingsworth, A, Koh, Y, and O'Neal, EK. A three-week, low-carbohydrate, high-fat diet improves multiple serum inflammatory markers in endurance-trained males. J Strength Cond Res XX(X): 000-000, 2020-This study examined the effects of a low-carbohydrate, high-fat diet (LCHF) on inflammatory marker responses in middle-aged endurance athletes. Eight male runners maintained their habitual mixed diet (HMD) in the first phase of the study before switching to a noncalorically restricted LCHF diet (∼70% of kcals from fat; carbohydrate <50 g) for 3 weeks. Subjects completed a 50-minute fixed pace treadmill running protocol in a hot environment, followed by a 5-km outdoor time trial. Fasting serum samples were collected immediately after exercise and heat stress restriction, and again 24 hours after the exercise/heat stressor. Thirty inflammation markers were assessed using the multiplex flow immunoassay technique. Seven markers (BAFF/TNFSF-13, sCD30/TNFRSF8, sCD163, Chitinase3-like1, gp130SIL-6Rβ, sTNFR-1, and sTNFR-2) reached statistical significance (p < 0.05) favoring LCHF before exercise, and sCD30/TNFRSF8 favored (p < 0.05) LCHF before (HMD = 459 ± 111; LCHF = 296 ± 100) and after (HMD = 385 ± 104; LCHF = 285 ± 104 pg·ml) exercise. Although the current dietary intervention was short in duration, LCHF seems to offer some protection against multiple chronic inflammation markers for physically active men between ages 30 and 50 years.

Ketogenic Diet: from the Historical Records to Use in Elite Athletes

PURPOSE OF REVIEW

To review the available literature/evidence on low carbohydrate/high fat (LCHF) and low carbohydrate ketogenic (LCKD) diets' effects on human athletic performance and to provide a brief review of the physiology and history of energy systems of exercise.

RECENT FINDINGS

Multiple studies have been conducted in an attempt to answer this question, many within the last 3-5 years. Studies are heterogenous in design, intervention, and outcome measures. Current available data show that LCHF and LCKD do not significantly enhance or impair performance in endurance or strength activities. However, there is a trend towards improved body composition (greater percent lean body mass) across multiple studies. While this may not translate to enhanced performance in the primarily laboratory conditions in the reviewed studies, there could be a benefit in sports in which an athlete's strength-to-weight ratio is a significant determinant of outcome.

A 28-Day Carbohydrate-Restricted Diet Improves Markers of Cardiometabolic Health and Performance in Professional Firefighters

Waldman, HS, Smith, JW, Lamberth, J, Fountain, BJ, and McAllister, MJ. A 28-day carbohydrate-restricted diet improves markers of cardiometabolic health and performance in professional firefighters. J Strength Cond Res 33(12): 3284-3294, 2019-We investigated the effects of a 4-week ad-libitum, nonketogenic, carbohydrate-restricted (<25% of calories) diet (CRD) on cardiometabolic and performance markers in firefighters (FF). Subjects (n = 15) completed 9 sessions (trials 1-3 [familiarization], trials 4-6 [baseline], and trials 7-9 [post-CRD]). Following habitual western diet, anthropometric measures were assessed, glucose tolerance measured, and then completed a graded cycling test, maximal Wingate test, and conducted their FF physical performance assessment (FPPA) to measure performance while metabolic variables and perceptual responses were recorded. Subjects then adhered to a CRD for a 4-week duration and returned for repeat testing. Body fat as measured by BodPod, and 7-site skinfold thickness decreased (p < 0.01), and a decrease was observed in blood pressure (BP) (p < 0.01; ∼5 mm Hg) after CRD. There were no differences found for glucose tolerance, but an increase was found for fat oxidation rates (p < 0.01; ∼0.07 g·min) and a decrease in carbohydrate oxidation rates across a range of intensities (p < 0.01; ∼0.24 g·min). Finally, the 2.41-km run and pull-up performance during the FPPA improved (p < 0.01; ∼41 second and 3 repetitions, respectively) and with no differences observed between treatments regarding the Wingate test. To date, this is the first CRD implemented with FF and resulted in decreased fat mass (∼2.4 kg), BP, and improvements to performance on the FPPA while preserving high-intensity exercise. These data suggest that a 28-day CRD can benefit markers of health in professional FF without detriments to occupational performance.