What's Under That Fur Coat?

My cat is fattening up. She's gone from 7.5 pounds to about 10 in 6 months. That's like me putting on 25 pounds. But we're not talking about me. She's still average, but I see other cats in the neighborhood and wonder if there's something in the water. Now that she's a teenager, I worry she might have a boyfriend. We were gone for two weeks over Christmas...I saw no evidence of partying, but she's always been pretty tidy. And secretive. I should have never gotten her that cell phone. How she is able to text without thumbs...Let's just say her weight gain is legit, though, and she's on her way to becoming a fatty. Is she an apple or a pear? I'm thinking pumpkin. Most fat cats are really big around the middle and have the same sized head of a normal cat. That's the route she's going to take, I can see it in her gut. I just don't understand the weight gain. She eats the same thing every day: crunchies. That's the scientific name for Iams orange bag hard food that comes in little triangle-shaped what I thought were "bite sizes." I watched her this morning. She eats three in one bite. But she only takes two bites and then walks away like it's the worst thing she's ever tasted in her life. Last night she chased a dropped grape around the living room. She seems sensible about her diet and gets plenty of exercise. Her litter box is in the basement. Sometimes she sprints three flights just to take a whiz. Granted, she sleeps two hours in a sunbeam by the sliding glass door, four hours in a box of coats in the bedroom, three more hours while watching TV (she is a Biggest Loser FANATIC!!!) and another 10 hours through the night practically on my face. So maybe she could be a little more active, but I think her bursts of panicked galloping from one end of the house to the other burn at least 7 calories each time. That's probably two bites of crunchies. I checked the food bag, not a lot of info there other than she shouldn't be eating more than a cup a day for her weight class. The chart goes up to 20 lbs. What is that, cougar? I have nothing against fat cats, I just wonder how they got to that point. I imagine them eating whole birds and standing up just to pee. I think a pair of tight jeans might help. If cats wore clothes, it would be a whole different ball game. When you can see folds flopping over fabric, it's a bit of an inspiration. But Maverick's not quite there yet; she falls asleep reading Shape magazine just like her Momma(s).