Beyond vectorial bioelectrical impedance: Assessing body composition changes with novel electrical parameters in...

Rapid weight loss with restricted diets can cause muscle mass decline. The aim of this work is to evaluate a new method for representing the raw electrical values obtained in the bioelectrical impedance analysis (BIA) in patients with obesity and osteoarthritis undergoing a meal-replacement diet.

We conducted a 1-group intervention study with meal-replacement diet for 3 months in patients with osteoarthritis prior to orthopedic surgery. Anthropometry and BIA was registered at baseline (B) and 3 months (3M) after the intervention. We have calculated traditional estimations of body composition over the raw electrical parameters of BIA parameters and a new bioelectrical impedance vector analysis (BIVA) based method to detect nutrition (NP), hydration (HP) and fat (FP) parameters without estimation.

A total of 272 patients (23.16% men; 76.84% women) were analyzed. There was a correlation between NP and body composition estimates (body cell mass [BCM] standardized by height (BCM/h): men: 0.96; p<0.01; women: 0.88; p<0.01). The correlation coefficient between HP and estimated total body water was 0.769 for men and 0.63 for women (p<0.01 in both cases). The correlation coefficient between FP and estimated fat mass (FM) standardized by height was 0.83 for men and 0.89 for women (p<0.01). There was a significant decrease in body weight (B: 99.33(15.0)kg; 3M: 92.03(16.0)kg; p<0.01); and FM (B: 49.93(6.67)kg; 3M: 44.22(9.08)kg). There was no difference in BCM and fat free mass. In new parameters a decrease in NP (B: +0.50(0.31); 3M: +0.42(0.42); p=0.03) and FP (B: +0.49(0.17) was reported; 3M: +0.38(0.16); p<0.01), although there was no difference in HP.

The new interpretation of BIVA as NP and HP have a high correlation with the body composition parameters estimated by regression models, and they report changes in body composition after a partial meal-replacement diet such as regression equations.