Is it possible to turn your manboobs into pecs with the right diet and exercise?

Yes: Diet combined with focused exercise to tone the fat in that area can reduce man boons. However, depending upon severity and amount of weight loss incurred cosmetic surgical procedures may be required to completely obliterate them.

No: You will likely find that unless the increased breast size is caused by adipose tissue, that diet and exercise will not change the size/shape of your breast. If persistent, surgical intervention may be helpful. Gynecomastia is often best treated with partial excision of the prominent glandular tissue as well as liposuction surgery of the peripheral chest area.