Differences in mechanisms between weight loss-sensitive and -resistant blood pressure reduction in obese subjects

This study was conducted to clarify the mechanisms involved in the sensitiv ity for blood pressure (BP) reduction in response to weight loss. In partic ular, we focused on the contributions of sympathetic nervous system activit y and fasting plasma leptin and insulin levels to BP levels during weight l oss in obese subjects with weight loss-sensitive and -resistant BP reductio n. Sixty-one young, obese untreated hypertensive men (FIT) and 52 obese nor motensive men (NT) were enrolled in a weight loss program consisting of a l ow caloric diet and aerobic exercise over a 24-week period. At entry and at week 24, body mass index (BMI), BP, plasma norepinephrine (NE), leptin and insulin were measured. Successful weight loss and BP reduction were respec tively defined as a more than a 10% reduction in BMI or mean BP from baseli ne at week 24. More than 60% of subjects in either group successfully achie ved weight loss by this definition. The percentage of subjects who successf ully achieved BP reduction was higher (64%) among those subjects who achiev ed weight loss than among those who did not (22%). Plasma NE level at entry in subjects who failed to achieve BP reduction despite weight loss was sig nificantly higher than that in subjects who succeeded in BP reduction. Plas ma leptin and insulin levels were similar between subjects with and without BP reduction. In addition, the absolute decrement and percent decrement in plasma NE in subjects who succeeded in BP reduction were significantly gre ater than those in subjects who failed to reduce their BP. Absolute and per cent decrements in plasma leptin and insulin were similar in both groups. T hese results suggest that individuals who are resistant to weight loss-indu ced BP reduction have more sympathetic overactivity both at the out-set of and during weight loss.