Like any other muscle in the body, studies have shown that when a man doesn't exercise his "Johnson" for an extended period of time, he's more likely to develop erectile dysfunction because sex helps to protect blood vessels and nerve fibers that are necessary for men to have an erection. It turns out that those who were having sex without a condom were significantly less depressed than those who were using condoms or not having sex at all. So if you go from having regular sex to none, and you notice that you've gained a few extra pounds, this could be why. Whatever the reason is, abstinence can have profound effects on your body, health, mood, and even performance. Seems like it might be a double edged sword. A study in the Journal of Sexual Medicine found that postpartum women who had not resumed sex yet were actually more concerned with their partner's needs and feelings about sex than their own. Your immune system gets weaker Orgasms are incredibly beneficial to your immune system, as psychologists Carl Charnetski and Francis Brennan Jr found. According to the North American Menopause Society, regular intercourse is important for vaginal health after menopause. That means you'll be more likely to get up and get to your workout and you might even be able to push through a bit more discomfort on the treadmill than usual. Read More What having a threesome is actually like, according to people who've tried Many of the effects apply to women entering the menopause Image: You may gain weight Shutterstock You might not realize just how many calories you're burning in between the sheets. Usually it's just a yeast infection or the result of some seriously tight jeans, but not having sex means you no longer have to worry — about most STIs at least. Maybe you and your partner have lost a bit of the spark in your love life. Changing positions, taking control on top, and even moaning every now and then will burn significantly more. Although studies have shown that depression and a lack of sex are linked, this reflects an association, not cause and effect.