Everyone's body is different, not one-size fits all on how long it will take to see changes in your body when you start working out. It also depends on the kind of workouts you're doing, and what your lifestyle is like. At a physiological and hormonal level, changes start to occur in the body instantly after a workout, but most people will start actually seeing results within the first month or two of making regular workouts part of their weekly routine. These results will start small but will improve and become more noticeable as time goes on.
Change is mainly determined by the condition your body is in when you begin training.
If you've never exercised, you will start seeing results quickly. Even if your workouts are basic. You'll experience increases in strength, fitness and endurance after the first couple weeks of training. If you are at an intermediate level, or have trained on and off for some time, you'll more likely see results after the first month or two. If you're advanced, such as an athlete or person who has been training consistently for years, noticeable increases in strength or fitness will take a couple of months, as the body is already highly conditioned. Hope that helps!
I agree with mike... I started working out 6 weeks ago and noticed results around 4 week, and now a few people have asked if I've lost a bit of weight... Work hard and be patient... It's worth it... Good luck
One thing I like to live by is
4 weeks for results
8 weeks for you to see results
12 weeks for others to see your result