Malnutrition in cancer patients is one of the most influential factors in the evolution and mortality of such patients. To reduce the incidence of malnutrition, it is necessary to establish a correct nutritional intervention. For this purpose, precise tools and indicators must be developed to determine the patient’s condition. The main objective of this systematic review and meta-analysis was to analyze the relationship between different nutritional strategies, phase angle (PA), and handgrip strength in patients with cancer, with the secondary objectives being the modification of other indicators of nutritional status, such as weight and body mass index (BMI). A systematic review of randomized clinical trials was carried out in March 2023 in the databases PubMed, Web of Science, Cochrane, and Scopus. As a risk-of-bias tool, RoB 2.0 was utilized. A total of 8 studies with a total of 606 participants were included in the analysis. A significant increase in PA was observed after the different nutritional strategies (SMD: 0.43; 95% CI: 0.10 to 0.77; p = 0.01; I² = 65.63%), also detecting a significant increase in handgrip strength (SMD: 0.27, 95% CI: 0.08 to 0.47; p = 0.01; I² = 30.70%). A significant increase in PA and handgrip were observed in cancer patients subjected to different nutritional strategies. These results suggest that these indicators could be used in the nutritional and functional assessment of the patients.

Background/Objectives: The objective of this meta-analysis was to determine the impact of bariatric surgery on phase angle (PhA) and other bioimpedance measures among adults with obesity, comparing the effects of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). Methods: A systematic review and meta-analysis were conducted following PRISMA guidelines, including studies up to May 2024 from MEDLINE, Scopus, Cochrane Library, and Web of Science. Eligible studies assessed PhA changes pre- and post-bariatric surgery in adults with BMI ≥ 30 kg/m². Data on PhA, fat mass (FM), fat-free mass (FFM), body cell mass (BCM), weight, and BMI were extracted and analyzed. Results: Thirteen studies with a total of 1124 patients were included. Significant PhA reductions were observed at 6 months post-surgery (effect size: −1.00; 95% CI: −1.11 to −0.89; p < 0.001), with a more substantial reduction in RYGB patients compared to SG. FM and FFM decreased significantly at 12 months (FM: −27.58; 95% CI: −32.58 to −22.57; p < 0.001; FFM: −10.51; 95% CI: −12.81 to −8.94; p < 0.001). Weight and BMI showed marked reductions at 6 months (Weight: −31.42 kg; 95% CI: −37.28 to −25.26; p < 0.001; BMI: −11.39; 95% CI: −12.60 to −10.18; p < 0.001), with sustained decreases at 12 and 24 months. Conclusions: Bariatric surgery significantly reduces PhA, FM, FFM, weight, and BMI, with initial greater impacts observed in RYGB compared to SG. PhA shows potential as a marker for monitoring post-surgical recovery and nutritional status. Further long-term studies and standardized measurement protocols are recommended to optimize patient management.

Background: Roux-en-Y gastric bypass (RYGB) is a highly effective treatment for severe obesity, achieving substantial weight loss and metabolic improvement. Beyond weight, assessing body composition and functional markers is essential. Phase angle (PA), obtained through bioelectrical impedance, is a relevant indicator of cellular integrity and nutritional status. The rise of glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide (GLP-1 and GLP-1/GIP) agonists makes comparison with surgical outcomes increasingly important. This study aimed to evaluate changes in fat mass, lean mass, hydration, and PA after RYGB and compare these findings with evidence from pharmacological therapies. Methods: A retrospective observational study was conducted in 15 patients (18–50 years, BMI > 35 kg/m²) at Quirón Salud Hospital Torrevieja. Body composition was assessed using multifrequency bioelectrical impedance (TANITA BC-980) before surgery and at 3 and 12 months. All patients received structured nutritional follow-up. Repeated-measures ANOVA and the Friedman test were applied. Results: After 12 months, weight decreased by 40.06 ± 11.86 kg; fat mass by 30.43 ± 10.81 kg; and fat-free mass by 9.64 ± 5.31 kg. PA declined 11% during the first 3 months and then stabilized. Women lost more fat mass; men lost more lean mass. Conclusions: RYGB combined with nutritional support produces high-quality weight loss with relative preservation of lean tissue and stabilization of PA, which proves valuable for postoperative monitoring.