Association between blood pressure and insulin resistance in obese femalesduring weight loss and weight rebound phenomenon

The purpose of this study was to investigate the effect of weight loss on b lood pressure and its related variables in moderately obese Japanese female s, including an investigation of the rebound phenomenon. Study I examined t he effects of weight loss on blood pressure in 138 moderately obese, nondia betic females (BMI 29.3 +/- 0.3 kg/m(2); age, 46.3 +/- 0.8 years) during a 3-month therapeutic dietary and exercise program. Study II investigated the effect of weight rebound on blood pressure over an additional 21 months of exercise in 48 subjects from Study I subjects. After 3 months, the BMI sig nificantly decreased to 27.9 +/- 0.3 kg/m(2). Abdominal total fat, visceral fat (V), and subcutaneous fat (S) also decreased significantly. In additio n, the summation of insulin (Sigma IRI), plasma glucose (Sigma PG) and HOMA during 75 g oral glucose tolerance test also all significantly decreased. Significant decreases in both the SBP and DBP were observed after the 3 mon th weight reduction program. Multiple regression analysis revealed that the reduction in SBP was significantly and positively associated with the redu ction in log ZIA] and the reduction in log 24h-urinary norepinephrine excre tion at the end of Study I. The DBP showed a significantly positive associa tion with the log Sigma IRI. With regard to the weight rebound phenomenon, Study II showed that the SBP, DBP and Sigma IRI all increased significantly , and a positive correlation was observed between the changes in the SBP an d those in the log Sigma IRI. However, no such correlation was observed reg arding the abdominal total fat and visceral fat during both periods. These results suggest that weight loss therefore caused the BP to decrease due to both an improvement in hyperinsulinemia and a decrease in the adrenergic a ctivity which may be involved in the urinary catecholamine. As a result, hy perinsulinemia is thus considered to play an important role in the pathogen esis of blood pressure due to obesity not only during weight loss, but also during the weight rebound phenomenon.