• Lindsay Tobias

Fasting and Female Hormones: What you need to know

Intermittent fasting has been getting a ton of popularity lately (thanks alot, Gwyneth Paltrow).

But here's the deal, diet companies are hopping on this opportunity because most people don't understand what fasting is, who it could benefit, and who it WOULDN'T.


Anytime you are listening to nutrition advice, please get in the habit of asking yourself, "who is this information intended for?"

Taking every new trend, study, or dietary theory as something YOU need to apply is going to be exhausting, and will keep you from ever truly being sustainably healthy or confident in your health.


However you like to absorb your information (via video or text) I have got you covered!



What is Intermittent Fasting (IF)?


IF is not a diet in that it restricts WHAT you eat, but rather WHEN you eat.

The most common form of IF is the 16:8 protocol, made popular by Dr. Jason Fung and Dave Asprey of Bulletproof.

This means that 16 hours a day you are fasting, and 8 hours a day you are eating.

(This could mean your last meal of the night would be at 7 pm and your first meal the following day would be at 11 am)


Other popular fasting variations are eating 500 calories 2x a week, or the full 24, 48, or 72 hr fast.

(Can we see how desperately we are grasping at straws for more rules to follow?!)


Who is it for? (and NOT for?)


Most of the studies done for IF are done on men or postmenopausal women.

This is because at all four phases of a female's cycle, there are different hormones at play. Hormones that change the way we feel, function, and respond to stress (fasting).


Even the most gung ho Intermittent Fasting Guru's deem that it is not fitting for the following populations:

  • menstruating females

  • those struggling (past or present) with a disordered eating

  • pregnant or breastfeeding females

  • those under 18

What are the supposed benefits?

  • fights oxidative stress

  • improves digestion

  • helps the body burn more fat

  • supports appetite control

  • helps balance blood sugar levels

  • encourages brain health and cardiovascular health

During sleep, our bodies experience rest and digestion. Imagine waking up 3-4 times during the night to eat, how would you feel? Don't you think you would wake up bloated?


This is because it is so important for our digestive system to have a period of time without incoming food.

For most people, this is what SLEEP does naturally.


Females can experience some of the digestive benefits of IF simply by getting a full night's sleep and decreasing late night snacking.


According to a recent study including both men AND women,

"Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day."

Why do females respond to fasting differently than males?


Fasting a stressor to the body.


According to hormone expert Alisa Vitti, "...anytime a woman’s body gets a “starvation signal” from her environment (like not eating for a stretch of time), it goes into preserve and protect mode, where it holds onto weight (to survive the famine), increases production of the hunger hormones ghrelin and leptin (so that you feel famished and rush to get food ASAP), and slows down non-essential functions like reproduction (so you can keep yourself alive and not waste energy on growing a baby)."


Here are some causes of high stress:

  • body fat percentage (females start to see issues under 15% body fat, some higher)

  • overall intake of food (cough cough, FASTING)

  • consistency and reliability of food (FASTING)

  • high intensity or chronic endurance exercise

  • physical and emotional stressors (work, deadlines, moving, marriage, divorce, trauma, etc...)

Fasting can disrupt or stop the menstrual cycle.


Similar to calorie restriction, fasting can disrupt estrogen, LH (luteinizing hormone) and FSH (follicle stimulating hormone) production from the hypothalamus, and these babies are critical hormones for ovulation, energy balance, weight management, and cognition.


Imbalanced hormones lead to more imbalances. Say hello to some cortisol (the stress hormone) imbalances, and impaired thyroid function.


So all in all, it's not a great time.


Blood sugar control is improved in males during fasting while IMPAIRED in females.


Blood sugar control is one of the toted benefits of IF. Recent studies show that while men experience beneficial changes in blood sugar control, (even as much as reversal of Type 2 Diabetes!), females can experience the opposite.


Fasting can damage your relationship to food.


Fasting tells you to eat according to a clock, not according to your own hunger and fullness signals.

To someone struggling with listening to your body, this can further sever that relationship, and teach you to overeat when you are finally "allowed."


What happens when you are done following this trend? How will you eat when you aren't following endless rules?

Why do you feel that you need external rules in order to be healthy?

I teach clients this daily, this beautiful concept of understanding your health enough to CREATE YOUR OWN, and no longer be swayed by all of the noise. You can do this, too.