What do films, hotels, appliances and now food all have in common? They have a star rating system designed to help us make better choices. And while sitting through a mediocre film does little more than waste our time, the star rating system on packaged foods has promised better health. But can a simple label on packaged food be the answer to rising obesity? The recently introduced system has got its detractors. For starters, how does a system rating healthiness give a better score to hot chips than greek yogurt? We'll get to that shortly. And how can we make best use of the labels despite their limitations?