Both low-fat and low-carb diets work equally well to help people lose weight over two years, new research has shown.

You may have read reports this week that schools are to tell parents if their children have weight problems.

There are many reasons why schoolchildren are becoming fatter, less fit and less active: most are driven to school; they eat more junk food, consuming ever more fat, salt and sugar; parental fear means many young people stay indoors, and they devote more hours to watching TV and playing computer games than to playing sport.