What exactly is the “fat tax” paying for?

I was just reading Paul from Big Fat Blog’s take on the “fat tax”.  Every few months there is a new debate on taxing people for being fat to get back some of the costs of the burden that we place on the system.  Paul stated that we are already paying the tax, but its not being called that.
This got me to thinking when I pay more for a 2x shirt or size 40 slacks where does the extra money from that go?  Why did the fashion industry decide that it would charge more once you go above a certain size? If not the fashion industry, then who? Congress?
Considering the fact that the typical garment for a plus size individual is made from the same pattern used for smaller sizes there really is no logical explanation for higher prices.  The conclusion that I have come to is that its all about profit.  Since fat people are going to be quiet and pay whatever we are told then its to charge whatever rate.

There are some that say that the cost it too much on the manufacturers end to properly address plus sizes.  New garment tables, pattern redesigns, factory costs, etc.  I say bull.  If small startup businesses that carry plus size fashions can price there items at affordable rates then multi-billion dollar companies can do the same without charging more for plus sizes.

Another bright idea would be for a major company to pick up the contract and mass produce say Rosalee Women Size Apparel using her patterns and charge what would normally be charged instead of being lame and say that plus size clothing doesn’t make any money for us so we have to charge more for it.

If anyone else can answer the question as to where this extra money is going I would love to know or any other thoughts on this matter.