
Having low testosterone levels doesn't necessarily make you gain weight, said Scott Isaacs, MD, an endocrinologist, faculty member of Emory University School of Medicine, medical director for Atlanta Endocrine Associates, and author of Hormonal Balance: How to Lose Weight by Understanding Your Hormones and Metabolism. However, when you gain weight, your testosterone levels will decrease. “Obesity is the number one cause of low testosterone,” Dr. Isaacs said. "Taking testosterone alone rarely results in weight loss. Most patients need to change their eating habits.”