There is good news and bad news for you.
I have biked over 10,000 miles in the last 12 months and gained weight. The good news is that my fitness has improved. My average speed is up and my HR is down for a given workout. My wife, a biker, is bitterly complaining that biking alone does not reduce her weight. Do not get me wrong, she looks great and is full of energy and healthy, but no weight loss.
I did go from size 40 waist to size 34 waist about two years ago. (I am 6 ft tall) That was done with a stringend diet of fish and veggies and oatmeal for breakfast. My energy was down while I was on that diet. I now do performance biking and can eat more and better. But still have to watch the food intake. Well, I am 65 years old and you younger guys may have an easier time.