Randomized clinical trials of weight reduction in nonhypertensive persons

Abstract

Since 1987, four randomized controlled clinical trials with 872 nonhypertensive subjects have produced results on weight-reducing interventions, involving decreased caloric intake and/or increased expenditure, for effects on blood pressure (BP). The Hypertension Prevention Trial maintained a 3.5-kg net weight loss through 36 months with intake reduction alone. This program decreased BP by 2.4/1.8 mm Hg (systolic/diastolic) compared to controls, but both weight loss and blood pressure changes were smaller when combined with decreased sodium intake. A Stanford University trial achieved weight losses of 7.4 and 5.1 kg over 12 months with diet and exercise, respectively. Effects on clinic BP were in the range of 1.5 to 3.0 mm Hg and did not differ by intervention approach. The sole trial in children, conducted at University of Michigan, found similar weight loss (about 7 kg) and BP effects from limiting caloric intake over 20 weeks, regardless of inclusion of an exercise program; the latter did, however, result in greater reductions in percent body fat, heart rate, and serum insulin levels. The Primary Prevention of Hypertension trial tested a multifactor intervention including reductions in weight (mean, 2.7 kg), sodium and alcohol intake, and increased physical activity. During a 5-year period, clinic BP was reduced by 2.0/1.9 mm Hg, and the incidence of hypertension, by 52%. It is concluded that weight loss, however achieved, lowers BP in overweight nonhypertensive persons, and probably can contribute substantially to reducing the incidence of hypertension. Whether there are independent effects additive to weight loss from increasing physical activity and reducing sodium intake remains unknown.