1. If you're a teenage boy and you're experiencing enlarged and/or sensitive breasts, especially if you're not otherwise overweight, then this is likely due to hormone fluctuations (mainly increased levels of estrogen) and a diet/exercise routine will not help you--you can either wait it out (it will go away eventually, probably by the time you reach your late teens or early twenties), or you can see a doctor to discuss hormone replacement therapy.

2. Otherwise, your man boobs are likely caused by being overweight, and the best course of action is a solid diet/exercise routine (if you're not overweight but are older than a teenager, then it could still be due to a hormone problem and you should see a doctor), of which there are several important aspects.

3. Firstly, you should diet properly: anything that cuts your calorie intake down below what you are burning every day WILL work. You can take your pick from Atkins, South Beach, The Zone, or my personal favorite, the French/Medeterranian diet (the best book about this is called 'The Fat Fallacy', by Will Clower).

4. Next, I highly recommend strength training because not only does it burn as much if not more calories than an aerobic workout of the same duration (many people don't know this and think only an aerobic workout is good for burning fat--not true!), but it also will help to harden, tone, and sculpt your pecs/chest so that they will look and feel attractive once you have burned off enough fat for the muscles to be visible. I recommend working each muscle group (chest, arms, back, legs, etc.) only once per week, as you WILL need at least a week to recover (I realize professional body builders do it a lot more often than this but you must remember they have 2 things you don't: GREAT genetics, and even more importantly, LOTS of steroids), so you could do arms, chest, and abs on Monday, then legs and back on Friday, or whatever you want, so that you're strength training 2-3 times per week. Combine this with aerobic exercise on 3 OTHER days during the week, and you're exercising almost every day, now aren't you? Think that might burn some fat off? You better believe it will!

5. Aerobic exercise--not only is it great for burning off fat when you're not strength training, but it has the side benefit of significantly improving your health, especially that of your cardiovascular system. Another plus is that there's so many ways to get it done: running, swimming, aerobics, spinning, cycling, elliptical machines, tread mills, stair climbers, racquetball, basketball, rock climbing, etc., so just pick your favorite and do it for 20-30 minutes 3 times a week (if you're not already in decent shape you should start out with only ONCE per week and work up to 3 times per week).

Consider A Pre-Packaged Program:

A friend of mine, who struggled with man boobs for years, has put together a prepackaged program for guys who want to lose their man boobs together, and I highly recommend it to those that are serious about doing this and especially if you have a severe problem that previous weight loss techniques have been unable to help with, since the method he delves into has to do with hormone balancing--I personally saw him lose his man boobs in about 3 months time, even his doctor was surprised he did it--check it out here: