I started working out 4 weeks ago and i gained 4 pounds the first week. i still haven't lost it and i am not eating any differently?

Muscle vs. fat: HI! If you are keeping the same diet and depending on how much and what you are doing in your workouts it is conceivable to gain weight for at least two reasons: 1) if you are building muscle - MUSCLE WEIGHS MORE THAN FAT PER VOLUME! 2) your metabolism may be slowing due to improved body efficiency but that may increase your fatty tissue and hence body weight. So R U more muscular or fatter?

Agree with Dr Waters: You may also be filling yourself and actually eating more either due to increased hunger or rewarding yourself for exercising. My FitnessPal is a great app to track bit exercise and food and see what you are really consuming. People tend to underestimate their food intake.