The idea that "carbs are bad because they make you fat" is over simplified. Of all the things your body can burn for energy, carbs are the most efficient. Thus if you're not exerting much energy, but eating a lot of carbs, it only stands to reason that you get fat. And while you're not doing anything your metabolism is also dropping like a rock. This will aid you in your weight gain, but is very annoying if you're trying to lose weight.
So here's the idea. If'n you wanna start losing some weight you gotta work out a little bit. Aerobics for the win. Try this out and let me know how it goes. It worked REALLY well for me a couple of times.
Implementation. I prefer to do my working out in the evening, 3 nights a week for about 30 minutes or so. I have dinner a little early. Dinner consists of something with a stupid amount of carbs in it. Those instant pasta meals usually do it. (What are they called, like Pastaroni or something to that effect?) Anyways. Give yourself an hour or so for your food to settle. You shouldn't feel full to the brim when doing your work out. Not hungry, not full, just happy. Then do your aerobics. Really get into it too.
That's the beginning. After the first week of that your metabolism should be going into overdrive. The second week you do it you should experience the "runner's high." That's your body letting you know that your metabolism is in good working order. During and after the second week you can take it easy on the carbs. Just make sure you get enough.
But everyone works differently. Pay attention to what your body is doing. "Food coma" is usually a sign that your metabolism isn't high enough to warrant the amount of carbs you've just ingested. If the meal you just ate wasn't particularly high in carbs, then you could probably take advantage of some aerobics. If you ate a rather high carb content meal, well it's only to be expected that the food coma comes on with lots of carbs.
And may I recommend something else? Get off the scale. I've seen two instances already where my friends who were rather large dropped 4 dress sizes in the time we were working out together. I convinced them not to get on the scale for a while. But after they dropped 4 dress sizes they felt they were ready to see the numbers. Turns out they only lost about 25 pounds. Both of them almost quit on me.
Generally when people work out it's because they want to feel better about themselves when they look in the mirror, or because they don't want to feel exhausted after a 15 yard walk. Those then should be your bench marks. How do your clothes fit? Do you find you have more energy to do stuff during the day? If you walk around with a megaphone broadcasting your weight, then by all means stay on the scale.