Weight-Adjusted Waist Index as a New Useful Tool for Assessing Body Composition and Risk of Metabolic Disorders in Adult Women

(1) Background: Commonly used anthropometric indices have limitations that discriminate their relevance. The subject of this research was to evaluate the health risks associated with body composition using the new weight-adjusted waist index (WWI). (2) Materials and Methods: The research group consisted of two hundred and thirty-nine Caucasian women. Body composition was analyzed by the MF-BIA method using InBody 970. The WWI was calculated as waist circumference divided by the square root of weight. Biochemical parameters (lipid profile, glucose, hs-CRP and uric acid) were analyzed using a Biolis 24i Premium biochemical analyser. One-factor variance analysis, a post-hoc test, Pearson correlation analysis and WWI quartiles were used for the statistical evaluation. (3) Results: The results showed significant differences between WWI quartiles. Compared to the lowest quartile, participants in the highest quartile groups had the highest values of body weight (58.49 vs. 87.17 kg; p < 0.001), waist circumference (WC) (76.47 vs. 109.45 cm; p < 0.001), body mass index (BMI) (20.65 vs. 32.06 kg/m2; p < 0.001), waist-to-hip ratio (WHR) (0.84 vs. 1.03; p < 0.001), waist-to-height ratio (WHtR) (0.46 vs. 0.66; p < 0.001), fat-free mass (FFM) (44.97 vs. 49.12 kg; p < 0.001), fat mass (FM) (13.52 vs. 38.05 kg; p < 0.001) and visceral fat area (VFA) (56.94 vs. 150.62 cm2; p < 0.001), confirming a higher risk of obesity. The women in the highest quartile had significantly higher values of total cholesterol (TC), triglycerides (TG), glucose (GLU), uric acid (UA), high-sensitivity C-reactive protein (hs-CRP) and systolic and diastolic blood pressure (BP). The correlations showed a strong positive relationship of the WWI with WC (r = 0.924), VFA (r = 0.907) and FM (r = 0.901) and a strong negative relationship with %FFM (r = −0.9) and %SMM (skeletal muscle mass) (r = −0.887). The correlation analysis also confirmed a strong positive association with WHR (r = 0.964), WHtR (r = 0.944), FMI (r = 0.902) and BMI (r = 0.863). (4) Conclusions: Our results confirmed that the WWI is a useful tool for assessing fat and muscle components, as well as for assessing health risks.