Running on a treadmill is NOWHERE NEAR as good as running outside. I'm not sure why, but it doesn't work the muscles in the same way and it doesn't work the muscles as much overall.
I guarantee you if you RUN (and by that I mean a fast jog) every day for a month, you will lose weight. You will have to keep running to keep it off, though.
I'm talking 2-5 miles, 6 days a week. Obviously you won't start out like that, but you should be able to work up to that within a month, depending on how fit you already are.
As for the carbs/protein thing -- let me just say that everyone's body works differently. I went on the atkin's diet for a couple weeks (WHILE running I might add) and I did not lose a single pound! In fact, I even gained a few!
However, when I was running and eating 4000 calories a day, 90% of those calories from carbs, I was at my thinnest ever (I looked like a skeleton!). I had to start eating more protein (esp meat, as I was primarily vegetarian at the time) and fat in order to gain some muscle and weight so that I didn't look like a nasty skeleton.
Now, the carbs thing only really applies to when I am running, but even when I am not running, too much protein will make me gain weight. For me, it is very important to eat a LOT of veggies and fruit, and then eat smaller amounts of protein and carbs (this is when I am not exercising).
The other thing I have found helpful in maintaining my weight (I am currently at my thinnest ever while not running and eating normally), is eating certain foods at certain times of the day.
Morning -- carbs, occasionally a bit of protein (usually in the form of milk), fruit
Noon -- some carbs, some protein, some veggies,
Night -- primarily veggies, very little or no pure carbs, small amount of protein
As for fat, I don't really worry about it too much. I drink whole milk, I use butter and cheese, and I eat baked goods occasionally. But, I consume small amounts of all of these. I avoid processed foods (AND HYDROGENATED OIL, which is the devil's food), and I prepare 80% of my own food.