Fruit juices are very bad. They concentrate the sugar content of a lot of fruits into a small mass and volume. For instance apple juice is usually considerably more sugary than Pepsi, with around 11-12 g/100g sugar content, and also with a worse sugar profile, with 66% fructose, compared to HFCS's 55 percent as it is commonly used in soft drinks (note: fructose is the worse sugar). Other fruit juices are usually above 8% sugar too.