Lost your period? Maybe you just need to eat more. Many more. Losing your period to undereating is called hypothalamic amenorrhea and common, especially among women under thirty years of age.
Hypothalamic amenorrhea is sometimes misdiagnosed as polycystic ovary syndrome (PCOS) because both hypothalamic amenorrhea and PCOS can present with “polycystic ovaries” on a pelvic ultrasound exam.
Three signs of undereating and hypothalamic amenorrhea
If you miss your period with less food, you’ll likely have one or more of the following signs:
- no withdrawal bleed from the pill or a progestin-challenge
- low fasting insulin (less than 4 mIU/L or 25 pmol/L)
- a low ratio of luteinizing hormone (LH) to follicle-stimulating hormone (FSH).
You may also have polycystic ovaries (or not). Read Is it PCOS or hypothalamic amenorrhea?
How undereating stops menstruation
Too few calories or too little of any macronutrient (including carbohydrates) can shut down the hypothalamus’ signaling to the ovaries. This is not a malfunction; instead, the brain makes a smart decision to avoid pregnancy when there isn’t enough food to make a baby. It is also called relative energy deficiency, which is the ratio between energy intake, body mass, and energy expenditure (exercise).
Hypothalamic amenorrhea is like an “off switch” of ovulation.
Men do not have such an “off switch” because although the male hypothalamus can dial testosterone up and down, it cannot completely turn testosterone off. Why? A male hypothalamus never has to worry about having access to the 75,000 extra calories needed to grow a baby.
Ovulation can be turned on again by consuming more food and aiming for a daily intake of at least 2500 total calories and 200 grams of carbohydrate. With increased calories and carbs (mostly in the form of starch), ovulation should continue for six months. It takes that long because of the “100 days to ovulation” I describe Weather Adjustment Manual.
👉 Tip: Hormonal birth control is not an effective treatment for hypothalamic amenorrhea because pill bleeding is not menstruation.
Ovarian set point
But what about your friend who hasn’t lost her period even on a keto diet? Different women are more or less vulnerable to hypothalamic amenorrhea, depending on their ancestry. According to evolutionary biologist Grazyna Jasienska’s book Fragile Wisdom, different women have different “ovarian set points,” meaning different dietary energy requirements to ovulate.
Energy is the key to understanding ovarian function. ~Dr. Grazyna Jasienska
Have you lost your period on a low-carb or keto diet?
Do you have an eating disorder?
If you fear the idea of eating more, please consider whether you have an eating disorder. Approach it with self-love and self-forgiveness, and know that you are not alone. Eating disorders are common and nothing to be ashamed of.
Reach out for help.
