If one side of your chest is bigger than the other…
It depends if the asymmetry is muscular in nature, or due to fat/glandular tissue. To keep it simple, let’s say the left side of your chest is bigger than the right side (the same advice would apply if the right side of your chest was bigger than the left).
More Fat/Glandular Tissue On One Side
If there’s more fat/glandular tissue on the left side of your chest, then the first thing you should do is see your doctor, since asymmetrical gynecomastia is more likely to be associated with an underlying disease process than symmetrical gynecomastia.
If your doctor checks you and there is no underlying disease process, then I would advise you to proceed with natural male breast reduction techniques, as though you had symmetrical gynecomastia. The same methods that work with symmetrical gynecomastia, work with asymmetrical gynecomastia just the same. You can learn about these methods in my website, and in my program, How To Lose Man Boobs Naturally, here:
More Muscle On One Side
If you have more muscle in your left chest than right, then you can do two things:
1. Get a personal trainer to help you perfect your exercise form. Sometimes muscular imbalances come from poor exercise form.
2. You can try to balance things out by spending more time and effort in growing muscle on the weaker side of the body (i.e. your right side). You might for example, for some time, train just the right chest using a dumbbell, or doing single arm pushups.