On average we consume some 27 kilos of sugar every year - and that figure is on the rise. But is that a good thing, or is sugar the root cause of many of the world's biggest, not-so-sweet, health concerns? Ed Butler speaks to professor Robert Lustig, who is leading the fight against sugar, and gets a response from Sugar Nutrition UK. We go to Berkeley, California where a tax on sugary drinks has just been implemented. And we hear from a couple who rowed from California to Hawaii on a sugar-free diet.