Dissociation Between Long-term Weight Loss Intervention and Blood Pressure: an 18-month Randomized Controlled Trial

Abstract

Background: Obesity is associated with elevated blood pressure (BP). In patients with obesity and hypertension, weight loss lowers BP, but the long-term effect of weight loss on BP is less clear.

Objective: We aimed to assess the effect of long-term weight loss intervention on BP in normotensive and hypertensive subjects.

Design: Randomized controlled trial.

Participants: Two hundred seventy-eight subjects (mean age 47.9 ± 9.3 years, 89% male, 56% hypertensive) with abdominal obesity or elevated serum triglycerides and low high-density lipoprotein cholesterol were recruited.

Intervention: Eighteen-month weight loss intervention.

Main measures: Body weight and BP were measured at baseline, after 6 and 18 months.

Results: After 6 months of intervention, in the weight loss phase, body mass index (BMI) decreased by an average of -2.2±1.5 kg/m² (p<0.001) and both diastolic BP (DBP) and systolic BP (SBP) decreased by -2.1±8.8 mmHg and -2.3±12.9 mmHg, respectively (p<0.01 for both). The change in BMI was similar in normotensive and hypertensive subjects (-2.0±1.6 and -2.3±1.5, p = 0.246). However, DBP and SBP decreased significantly (-5.2±7.1 mmHg and -6.2±12.5 mmHg, respectively, p<0.001 for both) in hypertensive subjects, and increased in normotensive subjects (1.8±9.3 mmHg, p = 0.041 and 2.7±11.7 mmHg, p = 0.017, respectively). After 18 months, in the weight maintenance phase, BMI slightly increased (0.9±1.3 kg/m², p<0.001) but remained significantly lower than at baseline (p<0.0001). Unlike BMI, DBP and SBP increased significantly in hypertensive subjects (p<0.001) and returned almost to baseline levels.

Conclusion: Weight-loss intervention reduced BP in hypertensive patients, but this was not maintained in the long run.

Clinical trial registration: ClinicalTrials.gov Identifier: NCT01530724.

Keywords: blood pressure; body mass index; hypertension; randomized controlled trial; weight loss.

Figure 1

Changes in body mass index and diastolic and systolic blood pressure during weight loss (6 months) and weight maintenance phases (18 months) of dietary intervention. Black line, BMI (body mass index); orange line, DBP (diastolic blood pressure); blue line, SBP (systolic blood pressure). Paired samples t test was used for between time-points comparison. (a) Significantly different from time 0. (b) Eighteen months significantly different from 6 months. Statistical significant—p<0.05.

Figure 2

Changes in body mass index and blood pressure during the intervention among normotensive and hypertensive participants. Changes in (A) body mass index and (B) diastolic and (C) systolic blood pressure among normotensive (green line) and hypertensive (red line) participants, during weight loss (6 months) and weight maintenance (18 months) phases of dietary intervention. Paired samples t test was used for between time-points comparison. (a) Significantly different from time 0. (b) Eighteen months significantly different from 6 months. Independent t test was used for between groups comparison. Statistical significant—p<0.05.

Figure 3

The relation between changes in body mass index and blood pressure among hypertensive and normotensive groups. Mean change in (A, C) diastolic and (B, D) systolic blood pressure after 6 and 18 months of dietary intervention between quartiles of BMI changes, among normotensive (black bars) and hypertensive (gray bars) groups. Paired samples t test was used for between time-points comparison. Linear regression analysis was used to assess the trend between BMI change quartiles and changes in blood pressure. *p<0.05.