SHE WEIGHS HOW MUCH? WHAT?

Recently the wife and I took our cat to have her annual shots. One of the first things we have to do when we arrive at the vet is first weigh the cat. We put her on the scale and it came up at a whopping 18 pounds! What? My wife and I looked at each other. How much did she weigh the last time we brought her? 15 pounds was the reply. What? Now this didn't make sense. We've had our cat on a diet eating lo-cal food and she gains 3 pounds? I just don't get it. Maybe she has found a stash at a neighbors house or something. I dunno.....anyway we are back on another diet plan so stay tuned!