The hypothalamus receives signals from your body that let it know when hormone levels need to be adjusted.
Based on the signals it receives, the hypothalamus produces hormones that either stimulate or inhibit the production of estrogen, progesterone, and other hormones by your pituitary gland.
Research has shown that this complex system is highly sensitive to changes in calorie intake and weight
When your calorie intake or body fat percentage drops too low, signals may become impaired, leading to changes in a number of hormones released.
Without the proper balance of reproductive hormones, pregnancy cannot take place. The first sign of this is hypothalamic amenorrhea or having no menstrual period for three months or longer.
In an older study, when 36 underweight women with amenorrhea or infertility related to calorie restriction increased their calorie intake and achieved ideal body weight, 90% began menstruating and 73% became pregnant.
If you are trying to conceive, make sure to consume a well-balanced, adequate-calorie diet in order to ensure proper hormonal function and healthy pregnancy.
Summary: Consuming too few calories can disrupt reproductive hormone signals, leading to difficulty getting pregnant.