A randomized controlled trial of an innovative, user-friendly, interactive smartphone app-based lifestyle intervention for weight loss

Abstract

Objectives: Most electronically delivered lifestyle interventions are labor intensive, requiring logging onto websites and manually recording activity and diet. Cumbersome technology and lack of a human coach may have contributed to the limitations of prior interventions. In response, the current program of research created a comprehensive electronically delivered lifestyle intervention using a user-friendly, interactive, smartphone app-based model, and evaluated it in a randomized controlled trial.

Methods: Twenty-eight adults, body mass index 25-42 kg/m², with smartphones and sedentary jobs, were randomized to the intervention, along with conventional outpatient weight-management visits every 3 months, or to a wait-listed control group that received only weight-management visits. The intervention included wearable activity trackers, smartscales, food photography logs, physician-driven app-based behavioral coaching, and peer support via the app. The prespecified primary outcome was a comparison of change in weight in kilograms, in the intervention versus control group at 6 months.

Results: At 6 months, the intervention group experienced a statistically significant weight change of -7.16 ± 1.78 kg (mean ± SE, 95% CI -11.05 to -3.26, p < 0.01), which differed from the weight change in controls by -4.16 ± 2.01 kg (95% CI -8.29 to -0.02, p < 0.05, prespecified primary outcome). Weight change in the control group was -3.00 ± 1.05 kg (95% CI -5.27 to -0.73, p < 0.05). Waist circumference and hemoglobin A_1c significantly improved (intervention vs. control: p < 0.01, p < 0.05, respectively, prespecified secondary outcomes). Weight change in the intervention group correlated with numbers of food photographs participants shared (rho = -0.86, p < 0.01), numbers of their text messages (rho = -0.80, p < 0.01), number of times and days each participant stepped on the smartscale (rho = -0.73, p < 0.01; rho = -0.608, p < 0.05, respectively), and mean daily step counts (rho = -0.55, p < 0.05).

Conclusion: This app-based electronically delivered lifestyle intervention produced statistically significant, clinically meaningful weight loss and improved metabolic health. Engagement with the intervention correlated strongly with weight loss. Given the limited sample size, larger and longer studies of this intervention are needed.

Keywords: lifestyle intervention; smartphone app; weight loss.

FIGURE 1

Prespecified primary outcome: comparison of the changes in body weight in kg, from baseline to 6 months, in the intervention group versus the control group. Values are mean ± SE. n = 13 intervention, n = 15 control, p = 0.0488 by the unpaired two‐tailed t‐test

FIGURE 2

Body weights in the intervention and control groups over the 6 months of the study. Values are mean ± SE. *p < 0.05 for the comparisons of the changes in body weight at 3 months (prespecified secondary outcome) and at 6 months (prespecified primary outcome) between the two treatment groups (unpaired two‐tailed t‐test). Body weights at baseline were not statistically distinguishable between the two groups (Table 1). n = 13 intervention, n = 15 control. Calculated p‐values can be found in the legend to Figure 1 and in Tables 1 and 2

FIGURE 3

Weight change in kilograms from baseline to 6 months for each participant in the intervention group (panel A) and in the control group (panel B). The vertical arrows in each panel indicate participants who achieved ≥5% weight loss, a standard threshold for a clinically meaningful change. “X” denotes a participant who achieved <5% weight loss

FIGURE 4

Changes in waist circumference (panel A) and hemoglobin A_1c (panel B) over 6 months. Values are mean ± SE. **Changes in waist circumference at 6 months, intervention versus control, p = 0.0097. n = 13 intervention, n = 15 control. *Changes in hemoglobin A_1c at 6 months, intervention versus control, p = 0.0131. n = 9 intervention, n = 8 control

FIGURE 5

Correlations of each participant's weight change in the intervention group with objective indicators of different aspects of each participant's engagement with the app‐based lifestyle intervention over the 6 months of the study. Shown are correlations of weight change with total number of food photographs sent via the app (“shared”) (A), total number of text messages sent (B), total number of times on the smartscale (C), total number of unique days when the smartscale was used at least once (D), and average daily step counts (E). Displayed are Spearman's rank correlation coefficients (rho) and the corresponding p‐values. In panel A, one participant achieved a weight change of −5.48 kg and shared 60 food photographs, and another participant had a weight change of −5.53 kg and shared 59 food photographs, and so their data points mostly overlap on the graph; these numerical data are given in Table S3

FIGURE 6

Correlations of each participant's change in waist circumference in the intervention group with objective indicators of different aspects of each participant's engagement with the app‐based lifestyle intervention over the 6 months of the study. Shown are correlations of changes in waist circumference with total number of food photographs shared (A), total number of text messages sent (B), and average daily step counts (C). Displayed are Spearman's rank correlation coefficients (rho) and the corresponding p‐values