Regarding exercise, muscle growth and weight, here is my personal experience.
With regular exercise (walking, running and cycling), I have obviously increased my fitness.
I have not lost weight. I still remain around the same weight (70Kg) that I was 15 years ago.
But most interestingly, I have become thinner or leaner. I used to wear 42 short jacket, then it dropped to 40 short and now even that look too baggy and I bought 38 S in Christmas sale. Same with waist, It reduced from 34 to 32 and now 32 look bit too loose.