Yup, it's really simple.  Ok, so your skinny friends appear to eat more than you.  Maybe you somehow do have a slow metabolism (not really of course).  You're still just eating too much.  But really,  complaints about metabolism or the lack thereof directly reveal fatty priorities.  They think it's a blessing to have a "fast" metabolism because you can stuff your face more.  In reality, having a truly fast metabolism would make life pretty tough because of all the time, effort and money you have to spend on eating enough.