New York, Sep 9: If you are an obese man planning to get under the knife to loose that extra paunch, think twice. According to a study, undergoing a type of bariatric surgery may raise the risk of frequent sperm aberrations and lower fertility rates in men. The findings revealed that men who underwent Roux-en-Y gastric bypass(RYGB) surgery reported elevated levels of the estrogen hormone estradiol and deficiency in vitamin D, factors which could negatively impact semen and fertility. This reduction was despite improvements in weight, androgen levels and sexual quality of life following the procedure, the researchers said. "This study is one important piece in solving the puzzle of male infertility. The challenge is to see if correcting hormonal and micronutrient aberrations are enough to reverse male infertility," said Edward Lin, Surgical Director, at Emory University's Gastroesophageal Treatment Centre in Georgia. In a Roux-en-Y gastric bypass, only a small part of the stomach is used to create a new stomach pouch, roughly the size of an egg. The smaller stomach is connected directly to the middle portion of the small intestine (jejunum), bypassing the rest of the stomach and the upper portion of the small intestine (duodenum). For the study, published in Bariatric Surgical Practice and Patient Care, the team compared the long-term effects of weight loss following RYGB among a group of sexually active men attempting to conceive with a partner to the semen parameters and fertility of obese men who did not undergo bariatric surgery and to a control group of lean men.