Introduction Ketogenic diets (KDs) that elevate ketones into a range referred to as nutritional ketosis represent a possible nutrition approach to address the emerging physical readiness and obesity challenge in the military. An emerging body of evidence demonstrates broad-spectrum health benefits attributed to being in nutritional ketosis, but no studies have specifically explored the use of a KD in a military population using daily ketone monitoring to personalize the diet prescription. Materials and Methods To evaluate the feasibility, metabolic, and performance responses of an extended duration KD, healthy adults (n = 29) from various military branches participated in a supervised 12-wk exercise training program. Fifteen participants self-selected to an ad libitum KD guided by daily measures of capillary blood ketones and 14 continued their normal mixed diet (MD). A battery of tests were performed before and after the intervention to assess changes in body mass, body composition, visceral fat, liver fat, insulin sensitivity, resting energy metabolism, and physical performance. Results All KD subjects were in nutritional ketosis during the intervention as assessed by daily capillary beta-hydroxybutyrate (βHB) (mean βHB 1.2 mM reported 97% of all days) and showed higher rates of fat oxidation indicative of keto-adaptation. Despite no instruction regarding caloric intake, the KD group lost 7.7 kg body mass (range −3.5 to −13.6 kg), 5.1% whole-body percent fat (range −0.5 to −9.6%), 43.7% visceral fat (range 3.0 to −66.3%) (all p < 0.001), and had a 48% improvement in insulin sensitivity; there were no changes in the MD group. Adaptations in aerobic capacity, maximal strength, power, and military-specific obstacle course were similar between groups (p > 0.05). Conclusions US military personnel demonstrated high adherence to a KD and showed remarkable weight loss and improvements in body composition, including loss of visceral fat, without compromising physical performance adaptations to exercise training. Implementation of a KD represents a credible strategy to enhance overall health and readiness of military service members who could benefit from weight loss and improved body composition.

Animal data indicate that ketogenic diets are associated with improved mitochondrial function, but human data are lacking. We aimed to characterize skeletal muscle mitochondrial changes in response to a ketogenic diet combined with exercise training in healthy individuals. Twenty-nine physically active adults completed a 12-week supervised exercise program after self-selection into a ketogenic diet (KD, n=15) group or maintenance of their habitual mixed diet (MD, n=14). Measures of metabolic health and muscle biopsies (Vastus lateralis) were obtained before and after the intervention. Mitochondria were isolated from muscle and studied after exposure to carbohydrate (pyruvate), fat (palmitoyl-L-carnitine), and ketone (β-hydroxybutyrate+acetoacetate) substrates. Compared to MD, the KD resulted in increased whole-body resting fat oxidation (p<0.001) and decreased fasting insulin (p=0.019), insulin resistance (HOMA-IR, p=0.022), and visceral fat (p<0.001). The KD altered mitochondrial function as evidenced by increases in mitochondrial respiratory control ratio (19%, p=0.009), ATP production (36%, p=0.028), and ATP/H2O2 (36%, p=0.033) with the fat-based substrate. ATP production with the ketone-based substrate was 4 to 8 times lower than with other substrates, indicating minimal oxidation. The KD resulted in a small decrease in muscle glycogen (14%, p=0.035) and an increase in muscle triglyceride (81%, p=0.006). These results expand our understanding of human adaptation to a ketogenic diet combined with exercise. In conjunction with weight loss, we observed altered skeletal muscle mitochondrial function and efficiency, an effect that may contribute to the therapeutic use of ketogenic diets in various clinical conditions, especially those associated with insulin resistance.

Background: Acute ingestion of ketone supplements alters metabolism and potentially exercise performance. No studies to date have evaluated the impact of co-ingestion of ketone salts with caffeine and amino acids on high intensity exercise performance, and no data exists in Keto-Adapted individuals. Methods: We tested the performance and metabolic effects of a pre-workout supplement containing beta-hydroxybutyrate (BHB) salts, caffeine, and amino acids (KCA) in recreationally-active adults habitually consuming a mixed diet (Keto-Naïve; n ¼ 12) or a ketogenic diet (Keto-Adapted; n ¼ 12). In a randomized and balanced manner, subjects consumed either the KCA consisting of $7 g BHB (72% R-BHB and 28% S-BHB) with $100 mg of caffeine, and amino acids (leucine and taurine) or Water (control condition) 15 minutes prior to performing a staged cycle ergometer time to exhaustion test followed immediately by a 30 second Wingate test. Results: Circulating total BHB concentrations increased rapidly after KCA ingestion in KN (154 to 732 lM) and KA (848 to 1,973 lM) subjects and stayed elevated throughout recovery in both groups. Plasma S-BHB increased >20-fold 15 minutes after KCA ingestion in both groups and remained elevated throughout recovery. Compared to Water, KCA ingestion increased time to exhaustion 8.3% in Keto-Naïve and 9.8% in Keto-Adapted subjects (P < 0.001). There was no difference in power output during the Wingate test between trials. Peak lactate immediately after exercise was higher after KCA ($14.9 vs 12.7 mM). Conclusion: These results indicate that pre-exercise ingestion of a moderate dose of R-and S-BHB salts combined with caffeine, leucine and taurine improves high-intensity exercise performance to a similar extent in both Keto-Adapted and Keto-Naïve individuals.

Excess visceral adipose tissue (VAT) and VAT volume relative to subcutaneous adipose tissue (SAT) are associated with elevated health risks. This study compares fat measurements by dual-energy X-ray absorptiometry (DXA) and magnetic resonance imaging (MRI). In total, 21 control subjects (Control) and 16 individuals with metabolic syndrome (MetSyn) were scanned by DXA and MRI. The region measured by MRI was matched to the android region defined by DXA, and MRI reproducibility was also evaluated. In addition, liver fat fraction was quantified via MRI and whole-body fat by DXA. VAT measurements are interchangeable between DXA and MRI in the Control (R = 0.946), MetSyn (R = 0.968), and combined cohort (R = 0.983). VAT/SAT ratio did not differ in the Control group (P = .10), but VAT/SAT ratio measured by DXA was significantly higher in the MetSyn group (P < .01) and the combined (P = .03) cohort. Intraobserver (ICC = 0.998) and interobserver (ICC = 0.977) reproducibility of MRI VAT measurements was excellent. Liver fat fraction by MRI was higher (P = .001) in MetSyn (12.4% ± 7.6%) than in controls (2.6% ± 2.2%), as was whole-body fat percentage by DXA (P = .001) between the MetSyn (42.0% ± 8.1%) and Control groups (26.7% ± 6.9%). DXA and MRI VAT are interchangeable when measured over an anatomically matched region of the abdomen, while SAT and VAT/SAT ratio differ between the 2 modalities.

Synopsis The bio-mechanical properties of the stratum corneum are of great importance for the subjective perception of skin conditions (dry vs. normal), as well as for its multiple functions. The recently developed Gas Bearing Electrodynamometer allows us to measure objectively the viscoelastic properties of the stratum corneum in vivo and to evaluate, in terms of skin softness, the changes of this parameter induced by the application of emollients. The principle of the technique, as designed by Christensen et al., is briefly described in context with our results. During the probe movement, there was a modification of the skin surface relief: compression of the skin furrows ahead of the moving probe, and extension-flattening of the relief behind the probe. The variations of the skin softness were studied in context with the reproducibility of the measurements: the coefficient of variation was found to be about 3%. Considerably higher variations were found as related to: the anisotropy of the skin surface relief, various areas of the body, and individual differences. The effects of emollients and water on the skin softness were studied. Water had a clear effect but of very short duration (around 10 minutes). Water-containing emollients of the type o/w emulsions displayed a distinct long-lasting effect (followed up to 6 hours). Its magnitude was generally higher than that obtained with w/o emulsions. It was found that the emollient's non-volatile components (oil phase) play an important role in the product's softening effect. In conclusion, results to date have established this technique as a promising tool for studying skin softness in general, and effects of topical applications, new formulae and specific ingredients in particular.