Low fat chocolate is an abomination. Chocolate is more than a flavor: that luscious meltinyourmouthiness comes from giant awesome globs of cocoa butter. You can't get rid of the fat without destroying the essence of chocolate itself, but chemists have instead figured out how to magically replace it, using fruit juice.
The secret to good chocolate lies in the special type of fat that you find in cocoa butter. This fat comes in several different crystallized forms, and one of these, the β crystal, has a melting point of between 93 and 100 °F, which is why it melts in your mouth. So really chocolate has these delicious melty textural properties because of the crystal structure that the fat creates, not because of the fat itself.
With that in mind, chemists at the University of Warwick have managed to replace up to 50% of the fat in chocolate with fruit juice, without changing the way chocolate feels to eat. The trick is simple, if not straightforward: the chemists just took out a bunch of the fat inside that crystal structure and swapped it out with little blobs fruit juice measuring just 30 millionths of a meter in diameter. The crystal structure of the modified chocolate stayed exactly the same, meaning that the "mouth feel" didn't change at all, but it was suddenly half the fat. And fruity tasting.
This technique works for dark chocolate, milk chocolate, and white chocolate, and while the researchers tried it with orange and cranberry juice, you could use whatever flavor you like, or a mixture of water and ascorbic acid (vitamin C) to keep the chocolate taste intact. It's now up to the food industry to take over and start producing this new, healthier chocolate, and we're just excited because it means we can eat twice as much chocolate as we could before while still feeling the same amount of guilt. That is, none at all.