Impact of Intermittent Fasting Combined With High-Intensity Interval Training on Body Composition, Metabolic Biomarkers, and Physical Fitness in Women With Obesity.

Background: Intermittent fasting (IF) is a dietary approach that is widely popular due to its effects on weight and body fat loss, but it does not appear to ensure muscle mass preservation. Incorporating high-intensity interval training (HIIT) into an individual's routine could be an attractive and viable therapeutic option for improving body composition, lifestyle and health promotion. Problematizing the emerging situation of fighting obesity, led us to clarify gaps about IF and hypothesize that IF and HIIT in conjunction may protect against muscle mass decline without impairing nitrogen balance (NB), in addition to improving the physical fitness of women with obesity. Objectives: To evaluate the effects of IF alone and combined with HIIT on body composition, NB and strength and physical fitness in women with obesity. Methods: Thirty-six women (BMI 34.0 ± 3.2; 32.2 ± 4.4 years) participated and were randomly distributed into three groups: (1) Intermittent fasting combined with exercise group (IF + EX); (2) Exercise group (EX); and (3) Intermittent fasting group (IF). The interventions took place over 8 weeks and all evaluations were performed pre and post-intervention. The HIIT circuit was performed 3x/week, for 25 mins/session, at 70-85% of the maximum heart rate. The intermittent fasting protocol was a 5:2 diet with two meals within 6 h on fasting days, being 25% of total energy intake, plus 18 h of complete fasting. The protocol was performed 2x/week and 5 days of ad libitum ingestion. Resting metabolic rate (RMR) was measured by indirect calorimetry, body composition by BodPod®, NB from urinary nitrogen, food consumption by food records and physical and strength performance were measured by physical tests. ANOVA two-way repeated measures mixed model was performed followed by Sidak post hoc (p < 0.05). This project was registered in ClinicalTrials.gov, NCT05237154. Results: There were a reduction in body weight (P = 0.012) and BMI (P = 0.031) only in the IF + EX group. There was body fat loss in the IF + EX group (-4%, P < 0.001) and in the EX group (-2.3%, P = 0.043), an increase in fat-free mass in the IF + EX group (+3.3%, P < 0.001) and also in the EX group (+2%, P = 0.043), without differences between groups and the IF group showed no changes. The NB was equilibrium in all groups. All parameters of aerobic capacity and strength improved. Conclusion: Combining IF with HIIT can promote increments in fat-free mass, NB equilibrium and improve physical fitness and strength.

Taurine upregulates insulin signaling and mitochondrial metabolism in vitro but not in adipocytes of obese women.

OBJECTIVES: Based on taurine's beneficial roles in metabolic diseases in rodents and obese individuals, we investigated the effects of taurine supplementation on adipose tissue using transcriptome analysis, 3T3-L1 adipocytes, and subcutaneous white adipose tissue (scWAT) of obese women. METHODS: First, we applied bioinformatics analysis to evaluate the effect of the taurine synthesis pathway on the adipose tissue of several BXD mice strains. After that, using 3T3-L1 adipocytes, we investigated the effects of different taurine doses in proteins related to insulin signaling, lipid oxidation, and mitochondrial function. Finally, we evaluated the effects of taurine supplementation (3 grams, 8 wk) on the same proteins in the scWAT of obese women. RESULTS: The transcriptome analysis showed that the taurine biosynthesis pathway was positively associated with insulin signaling and mitochondrial metabolism in the scWAT of BXD mice. The experiments using 3T3-L1 cells highlighted that the taurine dosage has an essential function in taurine synthesis, insulin, and mitochondrial markers. In contrast, the 8-wk taurine administration did not change the basal insulin, proteins of the taurine synthesis or insulin pathways, lipid oxidation, or mitochondrial metabolism in the scWAT of obese women. CONCLUSIONS: For the first time, to our knowledge, we showed that supplementation with 3 g of taurine for 8 wk promoted no effect in the insulin signaling pathway in the scWAT of obese women. These findings bring new perspectives to investigate different taurine doses and the intervention period for human studies owing to the potential antiobesity activity of taurine.

Casein and Whey Protein in the Breast Milk Ratio: Could It Promote Protein Metabolism Enhancement in Physically Active Adults?

Due to the utilization of milk proteins such as whey protein (WP) and casein as sports nutrition ergogenic aids, the present study investigated the effects of the association of WP and casein in a ratio of 80:20, a similar ratio of human breast milk, on blood branched-chain amino acid (BCAA) profiles, markers of protein metabolism and delayed onset muscle soreness (DOMS), after a single bout of resistance exercise. A double-blind, crossover and acute study was carried out with ten men (age 29 ± 8 years; BMI: 25.4 ± 2.9 kg/m2; 77 ± 12 kg; 1.74 ± 0.09 m); each one consumed the following supplements randomly, one per session: WP, CAS (casein), WP/CAS (80% WP/20% CAS), CAS/WP (80% CAS/20% WP) and PLA (placebo). They were also subjected to the following evaluations: the one repetition maximum (1RM) test; resistance training session; blood extraction during each session to determine the BCAA profile; two food records; 3-day evaluation of DOMS (24 h, 48 h and 72 h) and nitrogen balance in each treatment. The intervention resulted in similar nitrogen urinary, creatinine and urea plasma levels and showed a positive nitrogen balance in all the trials. Regarding the BCAAs, the peak occurred at 60 min post-ingestion and remained higher until 120 min for WP, WP/CAS and CAS/WP. The DOMS was significantly lower for WP, WP/CAS and CAS/WP compared to the CAS and PLA treatments. There were no advantages in the association of WP and CAS in the BCAAs profile when compared to WP itself, but it induced a lower DOMS compared to CAS and PLA (Clinical Trial registration number: clinicaltrials.gov, NCT04648384).

Beta-alanine fails to improve on 5000 m running time despite increasing PAT1 expression in long-distance runners.

BACKGROUND: Beta-alanine has become a dietary supplement widely used by athletes due to its ergogenic effect. However, there is still no consensus on the performance benefit of beta-alanine on exercise lasting longer than ten minutes. The present study aimed to evaluate the effect of beta-alanine supplementation on running performance and the expression of TauT and PAT1. METHODS: This double-blind, randomized study enrolled 16 long-distance runners (37±8 years) who were randomly allocated to two groups: placebo (PLA) and beta-alanine (BA) (4.8 g/day 1) for four weeks. Maximal oxygen consumption, anthropometry, body composition, and food intake were determined. Before and after the intervention, the athletes undertook a 5000 m running time trial. Venous blood (TauT and PAT1 expressions) and ear lobe capillary blood (lactate) collected before and after exercise. Between tests, we monitored the training variables. RESULTS: The results were analyzed by t-tests and an ANOVA of repeated measures, with Sidak's post hoc (P<0.05). PLA exhibited lower body fat than BA (8.7±2.2 vs. 11.5±2.8%, P=0.04). After supplementation, there was an increase in PAT1 expression in BA when compared to PLA (1.17±0.47 vs. 0.77±0.18, P=0.04). No significant differences were shown for the 5000 m running time in PLA (PRE: 1128±72; POST: 1123±72s) and BA (PRE: 1107±95; POST: 1093±86s). CONCLUSIONS: Although beta-alanine supplementation increased PAT1 expression, there was no statistically significant improvement in 5000 m running performance. However, individual responses should be considered as the BA showed a higher delta than the PLA.

Performance of muscle strength and fatigue tolerance in young trained women supplemented with caffeine.

BACKGROUND: The aim of this paper was to verify the effect of caffeine supplementation on the muscular strength and fatigue tolerance of young trained women. METHODS: Eight women of 25±5-years-old, who had undergone a minimum of 12 months of continuous resisted training, Body Mass Index 20-23 kg/m2 were submitted to 4 tests: One Repetition Maximum (1-RM, kg) to pull down (PD), Hack Squat (HS), Bench Press (BP), and Knee Extension Exhaustion (drop-set, 100/80/60 kg, repetitions) (DS). They performed the tests in 4 consecutive blocks one-week apart crossover system: basal without caffeine (B); first caffeine (C1); placebo with starch supplementation (P); second caffeine (C2). Caffeine supplementation 6 mg.kg-1 30 minutes before. The paired t-test and repeated ANOVA with Tukey-Kramer were performed. RESULTS: Respectively for B, C1, P and C2 to each test were PD (52, 54, 56, 55, P>0.05); HS (99, 109, 108, 121*; P<0.001); BP (22, 26*, 25*, 27*; P<0.05); DS (28, 35*,**, 30*, 37**; P<0.001). To comparison of B, P and mean caffeine (C1+C2/2) results respectively were: HS (99, 108*, 115***; P<0.05); BP (22, 25*, 26*; P<0.05); DS (28, 30#, 36**; P<0.01 and P<0.001). The delta ([C1+C2/2]-[B+P/2]) were PD=0 (P>0.05), HS=12 (P=0.04), BP=3 (P=0.007), DS=7 (P=00.1). CONCLUSIONS: Caffeine improved tolerance to exhaustion and has tendency to improve strength in this young women. Probably caffeine supplementation is useful to improve performance in women engaged in sports with these physical valences. An investigation with a major numbers of volunteers could elucidate some controversies observed here.