Impact of weight loss with diet or diet plus physical activity on cardiac magnetic resonance imaging and cardiovascular disease risk factors: Heart Health Study randomized trial.

Objective: The primary aim of this study was to examine the change in left ventricular mass (LVM) in adults with overweight or obesity in response to a behavioral weight-loss intervention, with variable physical activity (PA) prescriptions.

Methods: A total of 383 adults were randomized to a 12-month intervention of diet modification (DIET), DIET plus 150 min/wk of PA (DIET+MODPA), or DIET plus prescription of 250 min/wk of PA (DIET+HIGHPA). LVM was measured with cardiac magnetic resonance imaging.

Results: Twelve-month weight loss was -10.2% (95% CI: -11.7% to -8.8%) in the DIET group, -11.0% (95% CI: -12.4% to -9.5%) in the DIET+MODPA group, and -10.3% (95% CI: -11.8% to -8.9%) in the DIET+HIGHPA group. LVM decreased at 12 months in the DIET group (-2.9 g [95% CI: -5.2 to -0.7]; p = 0.0114), with no change observed in the DIET+MODPA group (-0.8 g [95% CI: -3.0 to 1.5]; p = 0.4979) or the DIET+HIGHPA group (-1.1 g [95% CI: -3.3 to 1.1]; p = 0.3299).

Conclusions: Weight loss through dietary modification resulted in reduced LVM, whereas, when combined with at least 150 min/wk of prescribed moderate-to-vigorous PA, LVM was preserved. These may both be favorable adaptations to weight loss and PA in adults with overweight or obesity that warrant further investigation to understand the clinical implications of these changes on cardiovascular disease risk.