Weight loss by mobile phone: a 1-year effectiveness study

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/m(2)), 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; P(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; T(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.