Believe you me, it's an excellent way to lose weight. You won't get into race shape this way, but lose weight you can. I did. I was in almost the exact same situation (even similar weight and height). I lost 20 lbs over the course of about four or five months.

Basically, I rode about 13 miles each way to work and back for a total of about 26 miles, and I did this four days a week. I did group rides during the weekend. I stopped eating a huge amount in the evening; I cut my dinner portion in half. I didn't mess too much with my lunch portion, though I would eat less if I wasn't that hungry. I lost a steady one pound a week. You can do it faster, but you must suffer some hunger then; more than two pounds a week is pushing it. At one pound a week you don't really suffer hunger pangs at all.

So it is possible, and very easily doable. Just don't expect to get in shape in a matter of two or three weeks. It's a lifestyle change you are after, not a one time weight loss push. The key is to be consistent and not skip out on the commutes; anything less than three or four times a week doesn't really do anything for you; and to not increase your eating.