Background: The literature on whether physical activity (PA) and PA and diet (PA+Diet) mobile apps improve cardiovascular disease (CVD) risk factors is promising. Objective: The aim of this meta-review is to provide an evidence synthesis of systematic reviews and meta-analyses examining the influence of PA and PA+Diet apps on the major CVD risk factors. Methods: We systematically searched 5 databases until January 12, 2022. Included systematic reviews and meta-analyses (1) reported the CVD risk factor outcomes of BMI, waist circumference, body weight, blood pressure (BP), hemoglobin A(1c) (HbA(1c)), fasting blood glucose, blood lipids, or PA; (2) enrolled healthy participants >= 18 years who may or may not have the metabolic syndrome, diabetes mellitus, or preexisting CVD risk factors; (3) reviewed PA or PA+Diet app interventions integrating behavioral change techniques (BCT) to deliver their information; and (4) had a nonapp control. Results: In total, 17 reviews (9 systematic reviews and 8 meta-analyses) published between 2012 and 2021 qualified. Participants were middle-aged, mostly women ranging in number from 10 to 62,219. Interventions lasted from 1 to 24 months, with the most common behavioral strategies being personalized feedback (n=8), self-monitoring (n=7), and goal setting (n=5). Of the PA app systematic reviews (N=4), the following CVD risk factors improved: body weight and BMI (n=2, 50%), BP (n=1, 25%), HbA(1c) (n=1, 25%), and blood lipids (n=1, 25%) decreased, while PA (n=4, 100%) increased. Of the PA+Diet app systematic reviews (N=5), the following CVD risk factors improved: body weight and BMI (n=3, 60%), BP (n=1, 20%), and HbA(1c) (n=3, 60%) decreased, while PA (n=3, 60%) increased. Of the PA app meta-analyses (N=1), the following CVD risk factors improved: body weight decreased (-0.73 kg, 95% CI -1.45 to -0.01; P=.05) and PA increased by 25 minutes/week (95% CI 0.58-1.68; P<.001), while BMI (-0.09 kg/m(2), 95% CI -0.29 to 0.10; P=.35) and waist circumference (-1.92 cm, 95% CI -3.94 to 0.09; P=.06) tended to decrease. Of the PA+Diet app meta-analyses (n=4), the following CVD risk factors improved: body weight (n=4, 100%; from -1.79 kg 95% CI -3.17 to -0.41; P=.01 to -2.80 kg 95% CI -4.54 to -1.06, P=.002), BMI (n=1, 25%; -0.64 kg/m(2), 95% CI -1.09 to -0.18; P=.01), waist circumference (n=1, 25%; -2.46 cm, 95% CI -4.56 to -0.36; P=.02), systolic/diastolic BP (n=1, 25%; -4.22/-2.87 mm Hg, 95% CI -6.54 to -1.91/ -4.44 to -1.29; P<.01), and HbA(1c) (n=1, 25%; -0.43%, 95% CI -0.68 to -0.19; P<.001) decreased. Conclusions: PA and PA+Diet apps appear to be most consistent in improving PA and anthropometric measures with favorable but less consistent effects on other CVD risk factors. Future studies are needed that directly compare and better quantify the effects of PA and PA+Diet apps on CVD risk factors.
