A goal of dieting is often to reduce body fat.
However, experts in human reproduction have known for several decades that women need a certain amount of body fat in order to achieve the hormonal balance required for regular ovulation.
Changes to a woman’s body composition (i.e. percent muscle mass and percent fat mass) can disturb her monthly ability to release an egg and, if the changes progress to an extra lean extreme, her cycle may stop all together.
Adequate percent body fat for regular ovulation is likely a range between the low to mid 20s.