Mobile-Health (mHealth) is the fastest-developing eHealth sector, with over 100 000 health applications (apps) currently available. Overweight/obesity is a problem of wide public concern that is potentially treatable/preventable through mHealth. This study describes the current weight-management app-market. Five app stores (Apple, Google, Amazon, Windows and Blackberry) in UK, US, Russia, Japan and Germany, Italy, France, China, Australia and Canada were searched for keywords: 'weight', 'calorie', 'weight-loss', 'slimming', 'diet', 'dietitian' and 'overweight' in January/February 2016 using App-Annie software. The 10 most downloaded apps in the lifetime of an app were recorded. Developers' lists and the app descriptions were searched to identify any professional input with keywords 'professional', 'dietitian' and 'nutritionist'. A total of 28 905 relevant apps were identified as follows: Apple iTunes=8559 (4634, 54% paid), Google Play=1762 (597, 33.9% paid), Amazon App=13569 (4821, 35.5% paid), Windows=2419 (819, 17% paid) and Blackberry=2596 (940, 36% paid). The 28 905 identified apps focused mainly on physical activity (34%), diet (31%), and recording/monitoring of exercise, calorie intake and body weight (23%). Only 17 apps (0.05%) were developed with identifiable professional input. Apps on weight management are widely available and very popular but currently lack professional content expertise. Encouraging app development based on evidence-based online approaches would assure content quality, allowing healthcare professionals to recommend their use.