Does the amount of body fat you have affect your fertility? Rapid weight loss can upset your menstrual cycle, which in turn affects ovulation and conception. Not having enough body fat can also produce irregular periods or cause you not to menstruate at all. This can also have effects on ovulation. Neither of these factors makes you infertile, but they do reduce your chances of successful conception. Excessive body fat, or obesity, can also affect ovulation. Since fat cells produce estrogen, your estrogen levels might be high. Too much estrogen acts like birth control, causing you to ovulate inadequately or not at all. Obesity can also put you at a greater risk for gestational diabetes or disorders that can lead to miscarriage. Overall, body fat doesn't cause fertility problems directly, but it does contribute to your general reproductive health.