Background: Cardiac autonomic function may play a role in obesity-associated hypertension. Most studies on the effects of weight loss on blood pressure and autonomic function do not distinguish between acute or continuing weight loss and steady-state weight maintenance after weight loss.
Objectives: We sought to clarify the changes in ambulatory blood pressure, heart rate and heart rate variability as assessed by spectral analysis during rapid weight loss and extended weight maintenance.
Participants: Abdominally obese (body mass index 35.2 ± 2.1 kg/m2, waist 114.3 ± 9.0 cm) men and women (n = 41) with the metabolic syndrome.
Methods and results: The 34 men and women completing the 1-year weight maintenance period lost 14.6 ± 3.5 kg during the 9-week very-low-calorie diet and maintained a 12.5 ± 7.5 kg weight loss to the end of the trial. Ambulatory 24-h blood pressure decreased dramatically during the diet (-9.0 ± 8.0/-4.6 ± 4.9 mmHg), but had risen to near baseline levels by the end of weight maintenance (-2.2 ± 8.2 /-1.2 ± 6.1 mmHg). Night-time heart rate decreased (-5.5 ± 9.6 beats/min, P = 0.012), and heart rate variability total and low-frequency power measured during 5 min of controlled breathing increased by 46-56% (P = 0.003-0.09) during rapid weight loss. These changes gradually attenuated during weight maintenance, and only the change in night-time heart rate was still of borderline significance after 1 year of weight maintenance (-3.6 ± 8.6 beats/min, P = 0.063). Heart rate variability high-frequency power tended to increase during weight loss and weight maintenance.
Conclusion: Despite successful weight maintenance, the decrease in ambulatory blood pressure after rapid weight loss was largely transient. The increase in parasympathetic tone was more sustained, but also gradually attenuated during 1 year of weight maintenance.