The results of the pilot trial have been published in the Journal of Internet Medical Research.
The Department of Health has calculated the direct costs of obesity on the NHS to be £5.1bn a year and an estimated 40,000 people die annually from conditions attributable to being overweight or obese.
"Smartphone technology could be harnessed to promote health; generally people don't know how many calories they are eating daily. My Meal Mate really helped people monitor their food intake and resulted in an important amount of weight loss," said Professor Janet Cade, from the School of Food Science and Nutrition, who lead the project.
"The labelling on food packaging can help people to identify sensible food choices but it doesn't enable them to understand the cumulative effects of the foods they eat. Keeping a food diary allows us to see where we might be eating too much and the app has proved to be the most effective tracking method by far," added Professor Cade.
Unlike other currently available smartphone apps that are aimed at helping people monitor food intake and lose weight, My Meal Mate is the first free app to contain a large UK-based food database. This allows users to map their eating habits easily to the products they consume. It is also the first such app to be hosted for download on the NHS Choices website.
The pilot trial consisted of 128 overweight volunteers, split into three groups with each group using a different monitoring method. Their use of each method and their weight and other body measurements were monitored over six months.
"Whilst we wouldn't expect people to use My Meal Mate daily for the rest of their lives, it gives them the skills and education to monitor their diet themselves – to have a better understanding of portion sizes, nutritional content and the effect of exercise," said Michelle Carter, the lead author on the paper, who conducted the study as part of her PhD at the University of Leeds.
It is now available to download for Android smartphones from the NHS Choices website and from the Google Play Store.
The research was funded by a National Prevention Research Initiative grant, which is administered by the Medical Research Council. The app was developed by software company Blueberry Consultants.