Weight loss intervention in phase 1 of the Trials of Hypertension Prevention. The TOHP Collaborative Research Group

Phase 1 of the Trials of Hypertension Prevention was a collaborative, randomized controlled clinical trial designed to determine the feasibility and efficacy of selected nonpharmacologic interventions in reducing or preventing an increase in diastolic blood pressure.

Participants aged 30 to 54 years who had a high-normal diastolic blood pressure (80 to 89 mm Hg), and were between 115% and 165% of their desirable body weight, were randomly assigned to either an 18-month weight loss intervention (n = 308) or a usual-care control condition (N = 256). Intervention consisted of 14 weekly group meetings followed by monthly maintenance sessions. Intervention participants received training in behavioral self-management technique and were asked to make life-style changes aimed at achieving a moderate reduction in energy intake and an increase in physical activity.

The average weight losses in the intervention group at 6, 12, and 18 months of follow-up were 6.5, 5.6, and 4.7 kg for men and 3.7, 2.7, and 1.6 kg for women. The mean (+/- SE) change in diastolic blood pressure for intervention participants compared with controls at termination was -2.8 +/- 0.6 mm Hg for men and -1.1 +/- 0.9 mm Hg for women. For systolic blood pressure, the corresponding change was -3.1 +/- 0.7 mm Hg for men and -2.0 +/- 1.3 mm Hg for women. Blood pressure reductions were greater for those who lost larger amounts of weight. Sex-related differences in blood pressure response were largely due to the smaller amount of weight lost by women, and sex differences in weight loss could be accounted for by differences in baseline body weight.

During an 18-month follow-up period, this weight reduction program was shown to be an effective nonpharmacologic intervention for reducing blood pressure in overweight adults with high-normal blood pressure.