Denmark recently implemented a tax on saturated fat. Most of the economic research on the topic suggests that such taxes are likely to have little effect on weight and health. It appears the Danish goverment is finding out the hard way.
According to this story, here is the Danish experience:
Only one year after its implementation, the Danish government is planning to scrap the “fat tax”. The reason why: reports show that it simply doesn't work.
Denmark is now likely to abolish the tax levied on saturated fats, as empirical evidence shows that its negative effects outweigh the benefits for the Danish Treasury. In particular, reports point to job losses in the food processing industry and Danes crossing the German border to buy cheaper products.