One day, at the doctor's office

A woman walks into her doctor's office and says, "Doctor, I need to lose weight fast." 

The doctor ponders the request for a bit, and then replies, "Well, there IS a new, experimental treatment that you might want to consider. It was developed by a medical team in Switzerland. It’s called 'Reverse Ingestion,' and the way it works is, instead of taking in your food orally, you actually reverse the process and insert it into your rectum.”

Two months later, the woman shows back up at the office. "Doctor, it's a dream come true! I'm half the size I was!"

But the doctor notices that she is repeatedly bouncing up and down, so he asks, "Where did you get that nervous twitch?"

The woman replies, "I don't have a nervous twitch; I'm chewing bubble gum."