Background: Weight reduction affects the heart rate variability (HRV). It is possible that repeated weight reduction (weight cycling) decrease HRV more than single one. We investigated the effects of weight cycling on heart rate variability in Koreans.
Method: We studied 21 Koreans (12 males and 9 females), in prospective way for 3 months. We divided subjects into two groups, weight cycling (WC) group and non-weight cycling (Non-WC) group before weight reduction. We measured anthropometry, obesity related parameters and heart rate variability (HRV) at baseline and after 3 month-obesity treatment using cognitive behavior modification, low grade exercise, low caloric diet and medication if indicated. We observed the changes inanthropometry, obesity related parameters and HRV parameters between groups by nonparametric test.
Results: At baseline, only the MHR in the WC was lower than in the non-WC, and the other HRV parameters in the WC were higher than in NON-WC, but the differences were not statistically significant. After 3 months treatment, MHR, TP, LF, HF decrease, LF/HF increase in both groups, but these results showed no significance either. After 3 months treatment, the weight change showed more markable in the WC than in the NON-WC (WC vs Non-WC; -7.16 ± 3.75 vs -4.16 ± 2.16, P = 0.032). Serum homocysteine and triglyceride levels were lower in the WC than in the NON-WC before and after treatment.
Conclusion: The changes of HRV after weight reduction in Weight cycling subjects were similar with those in Non-Weight cycling subjects.

Keywords: Weight cycling, Heart rate variability, Obesity, Weight reduction