Sex increases a man´s production of testosterone and a woman´s production of estrogen. Estrogen also improves hair growth and the synthesis of collagen. Collagen strengthens the connective tissue of the skin, helping women fight cellulite and, therefore, obtaining tighter and smoother skin. Men benefit equally from a higher testosterone level as a result of an active sex life. They feel energetic, fitter and enjoy better moods. The muscles react and grow more from weight training. When both men and women climax it improves the blood flow in the skin which helps to keeping it looking young and toned.