BACKGROUND There are inconsistent results for the effectiveness of using smartphone applications (apps) or websites on weight loss. We investigated the efficacy of a smartphone intervention using a designated app that utilizes a lifestyle intervention-focused approach, including a human coaching element, toward weight loss in overweight or obese Korean adults.

METHODS One hundred four adults aged 20-60 years with a body mass index ≥23 kg/m², who signed up for a smartphone program for weight loss (using the Noom app), were recruited. Participants received an in-person orientation about the study and app use, and a baseline blood sample was obtained. The in-app intervention with daily behavior and nutrition education content and coaching lasted 15 weeks. The primary endpoint of the study was a change in weight. The secondary endpoints were changes in metabolic risk factors such as blood pressure, waist circumference, and glucose and lipid profiles. Body composition changes were also assessed, and body weight at 52 weeks was measured to ascertain long-term effects.

RESULTS Participants showed a clinically significant weight loss effect of -7.5% at the end of the 15-week program (P < 0.001), and at a 52-week follow-up, a weight loss effect of -5.2% was maintained. At 15 weeks, percent body fat and visceral fat decreased by -6.0 ± 5.4% and -3.4 ± 2.7 kg, respectively (both P < 0.001). Fasting glucose level also decreased significantly by -5.7 ± 14.6 mg/dL at 15 weeks. Lipid parameters showed significant improvements, except for high-density lipoprotein cholesterol. The frequency of logging meals and exercise was associated with body fat loss.

CONCLUSIONS This advanced smartphone app was a useful tool to maintain weight loss in overweight or obese people.