(1) Background: The influence of ketogenic diet on physical fitness remains controversial. We performed a randomized controlled trial to compare the effect of cyclical ketogenic reduction diet (CKD) vs. nutritionally balanced reduction diet (RD) on body composition, muscle strength, and endurance performance. (2) Methods: 25 healthy young males undergoing regular resistance training combined with aerobic training were randomized to CKD (n = 13) or RD (n = 12). Body composition, muscle strength and spiroergometric parameters were measured at baseline and after eight weeks of intervention. (3) Results: Both CKD and RD decreased body weight, body fat, and BMI. Lean body mass and body water decreased in CKD and did not significantly change in RD group. Muscle strength parameters were not affected in CKD while in RD group lat pull-down and leg press values increased. Similarly, endurance performance was not changed in CKD group while in RD group peak workload and peak oxygen uptake increased. (4) Conclusions: Our data show that in healthy young males undergoing resistance and aerobic training comparable weight reduction were achieved by CKD and RD. In RD group; improved muscle strength and endurance performance was noted relative to neutral effect of CKD that also slightly reduced lean body mass.

Myokines represent important regulators of muscle metabolism. Our study aimed to explore the effects of a cyclical ketogenic reduction diet (CKD) vs. a nutritionally balanced reduction diet (RD) combined with regular resistance/aerobic training in healthy young males on serum concentrations of myokines and their potential role in changes in physical fitness. Twenty-five subjects undergoing regular resistance/aerobic training were randomized to the CKD (n = 13) or RD (n = 12) groups. Anthropometric and spiroergometric parameters, muscle strength, biochemical parameters, and serum concentrations of myokines and cytokines were assessed at baseline and after 8 weeks of intervention. Both diets reduced body weight, body fat, and BMI. Muscle strength and endurance performance were improved only by RD. Increased musclin (32.9 pg/mL vs. 74.5 pg/mL, p = 0.028) and decreased osteonectin levels (562 pg/mL vs. 511 pg/mL, p = 0.023) were observed in RD but not in the CKD group. In contrast, decreased levels of FGF21 (181 pg/mL vs. 86.4 pg/mL, p = 0.003) were found in the CKD group only. Other tested myokines and cytokines were not significantly affected by the intervention. Our data suggest that changes in systemic osteonectin and musclin levels could contribute to improved muscle strength and endurance performance and partially explain the differential effects of CKD and RD on physical fitness.

Background: The influence of social media on adolescents’ eating habits is increasingly discussed, as social platforms often shape young people’s lifestyle choices and attitudes toward nutrition. This study aimed to examine whether the content shared on social media affects food choices, daily dietary decisions, and the overall approach of adolescents to nutrition. Partial objectives included identifying what types of nutrition-related content adolescents follow, whether it influences their behavior, and to what extent they are able to distinguish between reliable and misleading information. Methods: A quantitative online questionnaire survey was conducted among adolescents aged 15–19 years. A total of 356 responses were collected, of which 344 were analyzed after excluding respondents outside the age criteria. The sample consisted of 73.5 % girls and 26.5 % boys from various types of secondary schools. The questionnaire contained 27 questions covering demographic characteristics, eating habits, influence of social media on food choices, and self-perception. Data were processed in Microsoft Excel using descriptive statistics and expressed in absolute numbers and percentages. Results: Social media were shown to have a dual impact on adolescents. On the one hand, they can motivate healthier eating habits and support an active lifestyle. On the other hand, they often create pressure to conform to unrealistic appearance ideals and may promote unbalanced dietary practices. Respondents reported being influenced by nutrition- and fitness-related content, with varying levels of trust in its reliability. Conclusions: The study confirms that social media significantly affect the eating habits and attitudes of adolescents, with both positive and negative consequences. The findings highlight the importance of strengthening media literacy, critical thinking, and nutrition education, not only from professionals but also within schools and families.

(1) Background: The influence of ketogenic diet on physical fitness remains controversial. We performed a randomized controlled trial to compare the effect of cyclical ketogenic reduction diet (CKD) vs nutritionally balanced reduction diet (RD) on body composition, muscle strength and endurance performance. (2) Methods: 25 healthy young males undergoing regular resistance training combined with aerobic training were randomized to CKD (n=13) or RD (n=12). Body composition, muscle strength and spiroergometric parameters were measured at baseline and after 8 weeks of intervention. (3) Results: Both CKD and RD decreased body weight, body fat and BMI. Lean body mass and body water decreased in CKD and did not significantly change in RD group. Muscle strength parameters were not affected in CKD while in RD group lat pull-down and leg press values increased. Similarly, endurance performance was not changed in CKD group while in RD group peak workload and peak oxygen uptake increased.(4) Conclusions: Our data show that in healthy young males undergoing resistance and aerobic training comparable weight reduction were achieved by CKD and RD. In RD group, improved muscle strength and endurance performance was noted relative to neutral effect of CKD that also slightly reduced lean body mass.