This study is aimed to investigate alterations of HRV indices in different body weight disorders, which prevalently affect females.

Sixty-four healthy women (17-39 yrs) were distinguished as under-weight (UW), normal-weight (NW) and over-weight/obese (OW), according to their BMI. Subjects' body composition was measured by BIA. Subjects underwent a 5-min ECG recording, at rest. Spectral analysis was performed by the FFT method. The power of low frequency (LF) and high frequency (HF) spectral bands was measured. Poincaré plot descriptors (SD1, SD2) of RR intervals were considered, as well.

Significant differences were found in LF, HF and SD2. Compared to NW, a significant decrease of LF was observed in UW and OW subjects. Likely, a significant decrease in HF was observed merely in OW subjects. Also SD2 showed a significant decrease in UW and OW subjects. No difference was found between OW and UW subjects, in respect of each HRV indices. A significant second order polynomial regression was found between FFM and FM and LF, HF, SD2, respectively.

These results suggest a decreased sympathetic drive in UW and OW subjects and a parasympathetic withdrawal, observed only in OW subjects. Poincaré plot analysis showed a significant variability in UW and OW, reflecting the different temporal effects of changes in the parasympathetic and symphatetic modulation of heart rate. By considering the whole group of subjects, the significant correlation between HRV indices and FFM values evidenced a similar HRV pattern in both UW and OW subjects.