by Steve Brodie No man wants to be able to fill his partners bra. Man boobs can cause extreme psychological discomfort for men, especially as there aren't many women who fall head over heels for wobbly pecs. Knowing how to lose chest fat boils down to dealing with the causes appropriately. Female hormones is one of the main culprits. The basic cause is a hormonal imbalance between estrogen and testosterone, the main sex hormones. An excess of estrogen will cause a feminization of male bodies