Taxing Sugary drinks has zero effect on obesity

Advocates of taxing sugary drinks such as soda point to numerous studies that show that when you tax sugary beverages 1) The government gets more money from it's customers citizens and 2) there is a reduction in the purchase of sugary drinks.

That is great.  This is a tax that is supposed to help reduce obesity.  There has not been a single study to that it reduces obesity at all.  But, we feel better and the government gets more money.  

What is not to like?