I am 18 years and i think suffering from gynecomastia,but there is no pain. can i join gym to reduce weight and gynecomastia?

Unlikely to matter: About a half of males will undergo a transient nipple/breast enlargement at he onset of puberty. Normally it will resolve in 6m-2y as other hormonal changes kick in.Carrying around extra weight can aggravate the issue as fat can masquerade as breast tissue.Weight loss may help some but it cannot reduce true breast tissue.I would consult a surgeon about having it removed.