Objective: To investigate the short- and long-term effectiveness and the predictors of weight loss in a mobile phone weight-loss programme among healthy overweight adults.
Design: One hundred and twenty-five healthy, overweight (BMI = 26-36 kg/m2), 25-44-year-old, screened volunteers were randomized to an experimental group (n 62) to use a mobile phone-operated weight-loss programme or to a control group (n 63) with no intervention. Via text messaging, the programme instructed a staggered reduction of food intake and daily weight reporting with immediate tailored feedback. Assessments were at 0, 3, 6, 9 and 12 months for the experimental group; at 0 and 12 months for the control group. Main outcome variables were changes in body weight and waist circumference.
Results: By 12 months the experimental group had lost significantly more weight than the control group (4.5 (sd 5.0) v. 1.1 (sd 5.8) kg; F(1,80) = 8.0, P = 0.006) and had a greater reduction in waist circumference (6.3 (sd 5.3) v. 2.4 (sd 5.4) cm; F(1,80) = 55.2, P = 0.0001). Early weight loss, self-efficacy, contact frequency, attitudes towards the medium, changes in work and family life and changes made in dietary habits were the strongest predictors of weight loss.
Conclusions: This mobile phone weight-loss programme was effective in short- and long-term weight loss. As a minimum-advice, maximal-contact programme, it offers ideas for future weight-loss programmes.