Resting heart rate but not heart rate variability is associated with the normal-weight obesity phenotype.

Objective: To determine differences in resting heart rate variability (HRV) and heart rate (HR) between young adults with normal-weight obesity (NWO) and normal-weight lean (NWL).

Methods: A total of 65 normal-weight individuals (18-25 years old, 50 women, body mass index 18.5 to 24.9 kg/m) were included in this cross-sectional study. Body fat percentage was determined using a whole-body dual energy x-ray absorptiometry scanner. Resting HRV and HR were assessed with the Polar RS800CX. Forty-one participants were classified as NWO and 24 NWL using cutoff points for body fat percentage (33.3% for women and 23.1% for men).

Results: There were no differences in HRV between NWO and NWL groups (all p > .05). HR was higher in NWO (mean 70 beats per minute [bpm], standard deviation [SD] 8) than in NWL adults (mean 65 bpm, SD 10), the adjusted mean difference 5 bpm (95% CI, 0 to 10 bpm).

Conclusion: HR is a noninvasive biomarker and relatively cheap, fast, and easy to measure that could detect "apparently healthy" young individuals with an adverse cardiovascular disease risk profile despite presenting a normal body weight.