Exercise - Using compound lifts will strengthen muscle fibers and allow you to build testosterone. Not to mention exercising makes you feel good and look good. Great confidence booster. Being overweight can cause a hormonal imbalance so creating a doable workout schedule and sticking to it will help eradicate gynecomastia. HIIT (High Intensity Interval Training) shocks your body in a way that it releases masculine hormones that burn chest fat.
Nutrition - Eating a healthy balanced diet is key to a healthy life. Not only will a proper diet allow you to focus your energy more efficiently, you will be avoiding harmful hormone altering chemicals. Again, being overweight can cause imbalances in your hormones so mixing proper nutrition with an attainable workout program is highly recommended. Meats, fish, fruits, healthy fats and veggies should be given priority over pizza, burgers, alcohol and TV dinners.
Avoiding Hormone Disrupting Chemicals - Now, I understand you can't actually avoid all of these. Not only are there new ones being introduced all the time, many of these chemicals are contained in our daily use items. What you can do though, is minimize the exposure to these chemicals. Nutrition, as explained above, is one of the top sources of these chemicals.
Let's talk about underlying conditions for a moment. Your prostate, testicles and liver are crucial to the balance of your hormones. If an underlying condition is causing your gynecomastia, the only way to reduce your man breasts is to treat the cause. You must address that first and always consult your physician.
Changing your lifestyle and being consistent with diet and exercise is the best way to losing your man boobs naturally.