Background/Objectives: The purpose of this proof-of-concept study was to examine the effects oligosaccharide 6′-sialyllactose (6′-SL) supplementation (900 mg/d) during training on exercise performance and training adaptations in recreationally active males. Methods: In a randomized, double-blind design, 19 healthy males (24.4 ± 6.0 yrs, 174.9 ± 5.9 cm, 82.0 ± 15.2 kg, 27.1 ± 4.7 kg/m², 26.4 ± 6.9% body fat) ingested 3 × 300 mg/d of a placebo or 6′-SL for 12 weeks while partaking in a supervised resistance-training program while following their normal diet. Body composition (DXA), body water, submaximal lactate and substrate oxidation, 5RM dynamic muscular strength, ventilatory anaerobic threshold (VANT), peak aerobic capacity (VO₂), blood lactate, cycling anaerobic sprint capacity, and fasting blood samples were obtained at week 0, 6, and 12 of training and supplementation. Data were analyzed using multivariate and univariate general linear models (GLM) with repeated measures, along with assessments of mean changes from baseline and corresponding 95% confidence intervals. Results: Both groups observed positive training adaptations with no significant differences observed between groups in body composition, 5RM dynamic strength, or anaerobic sprint capacity. Significant interaction effects were observed VANT (p = 0.032), VO₂ at VANT (p = 0.028), and submaximal glucose and fat oxidation (p = 0.034) while time to reach peak VO₂ (p = 0.083), absolute (p = 0.075) and relative (p = 0.057) peak VO₂ approached significance. At Week 6, changes in time to peak effort (196 s [−16, 409], p = 0.068), absolute (0.76 L/min [−0.005, 1.53], p = 0.051) and relative (10.9 mL/kg/min [0.52, 21.5], p = 0.045), and fat oxidation (20.5% [3.1, 37.9], p = 0.023) were significantly greater in the 6′-SL group while VANT (−9.2% [−18.3, −0.04], p = 0.049), VO₂ at VANT (−4.8% [−9.8, 0.2], p = 0.06) and submaximal glucose oxidation values (−20.5% [−37.9, −3.1], p = 0.024) were lower with 6′-SL. After 12 weeks of training, VANT (−9.7% [−17.7, −1.5], p = 0.023) and VO₂ at VANT (−6.4% [−11.8, −1.0], p = 0.024) values were significantly lower in the 6′-SL group. No significant differences were observed in resting, submaximal, or maximal exercise blood lactate while the ratios of LDL to HDL (−0.27 [−0.53, −0.01], p = 0.042) and total cholesterol to HDL (−0.32 [−0.60, −0.04], p = 0.028) decreased significantly from baseline after 6 weeks of training with 6′-SL. Conclusions: 6′-SL supplementation did not promote greater gains dynamic strength, fat free mass or changes in body composition. However, while there was some evidence that 6′-SL supplementation influenced training-induced changes in aerobic capacity during the first six weeks, fewer effects were observed after 12 weeks. Moreover, several differences only approached significance in this small proof-of-concept study, so results should be viewed as exploratory and hypothesis generating for additional research.

Ashwagandha (Withania somnifera) has gained interest as an anti-stress agent due to its withanolide content. Ashwagandha’s adaptogenic nature, through regulation of the hypothalamic–pituitary–adrenal (HPA) axis, makes it a promising agent for improving responses to external stressors, including changes in body composition. Studies have demonstrated that ashwagandha can positively affect stress regulation, metabolism, and muscle strength, but how these adaptations impact body composition has not been thoroughly described. Theoretically, ashwagandha’s mechanistic effects may reduce body fat and increase muscle mass, thereby optimizing body composition. This review summarizes the current evidence on the effects of ashwagandha supplementation on body composition metrics and proposes mechanisms that explain the results. Therefore, this literature review analyzed the current literature examining changes in body composition metrics, including body mass, fat mass, lean mass, muscle mass, and anthropometric measurements, in adults when supplementing with ashwagandha. The discussion details specific protocol and population differences between the included studies and how these differences influence body composition results. The discussion also outlines future research directions on potential effects on weight management and sex-specific adaptation to better understand ashwagandha’s underlying effects on body composition.

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