Female Hormones and Intermittent Fasting

The superior gender, I’ll say it.  I am amazed by women, I always have been.  Women create life, carry around life for 9 months, birth life, then can feed life.  And when you think about the male contribution to all of that, I’m just saying it’s kind of embarrassing.  We just don’t pull out.  I mean we do our favorite thing and women do the rest.  I digress.

I told you that story to tell you this one.  Women and men are different, thank the Universe.  Since we are different, why are so many folks surprised that intermittent fasting is different for the genders?  Or is it?  I am not one to listen to bro science or??? What is the female version of bro?  Anyway I digress again.  The point is that I am a researcher, I will listen to anecdotal “evidence,” however I accept it like I do anything that is not peer reviewed and repeated, with the tiniest of grains of salt.

Intermittent fasting is highly individualized and that is the essence of what makes it NOT a diet and more of a lifestyle change.  When you think of diets certain ones come to mind automatically, WW, Atkins, Keto, South Beach, Calorie Restriction, blah to the blah squared.  I.F. is none of these or all of these depending on how you set up your program.  But the essence of intermittent fasting is not to change what you are eating or how much you are eating.  IF lets you decide when to eat, how long to eat and how long don’t eat.

12 x 12, 16 x 8, 20 x 4, 23 x 1, OMAD, 5:2, ADF (1) and on and on.  The numbers are arbitrary, because as I always say it is YOUR program, YOUR rules.  You don’t even have to stick to one you can do all of the above or make your own.  That’s the glory of IF, it’s all about you. But that’s not why we are here today.  We are here to discuss if intermittent fasting is beneficial, safe, and / or effective for females.

First let us take a look at what shit talk the naysayers say about IF for women.

Intermittent fast causes glucose intolerance in women

Um I call bullshit.  The study being used for this “fact” is one that used 8 women and 8 men. The main similarity for these folks were that they were all “non-obese”.  That’s it…  age, weight, height, gut bacteria, food groups, nope… not important.  They also used the p value, which in science means the probability or our best guess. The study concluded that women had a “statistically significant” longer glucose response related to alternate day fast than did men.  They did a 36 hour fast, fed, then after 21 days performed testing on 11 of the 16 participants.  So forgive me if I question the validity of a study that used the results of 11 people that the only differences and similarities is that they were either male or female and that they were both non-obese (4).

You’re in luck, a study of over 800 people, over 46,000 meals found blood glucose levels in response to foods are highly individual. The importance needs to be placed on personalized food choices, prepared based on complex factors such as your gut microbes and lifestyle. Surprisingly, the foods that raise blood sugar levels differ dramatically from person to person. Lifestyle also matters.  The same food affected blood sugar levels differently in the same person, depending, for example, on whether its consumption had been preceded by exercise or sleep.  The study also fed volunteers either a meal based on “good diet” or “bad diet” for a week not much more of an explanation there, except both had the same amount of calories.  The “good” diets indeed helped to keep blood sugar at steadily healthy levels, whereas the “bad” diets often induced spikes in glucose levels — all within just one week of intervention. Moreover, as a result of the “good” diets, the volunteers experienced consistent changes in the composition of their gut microbes, suggesting that the microbiome may be influenced by the personalized diets while also playing a role in participants’ blood sugar responses. (3)  So hopefully we can put the fact that women and men respond differently to food and glucose in the no shit category.  We respond differently to a lot of stuff.

Intermittent fasting causes amenorrhea, the absence of menstrual period

Does it though?  There is a lot of anecdotal “evidence” that intermittent fasting fucks with hormones, yeah no shit.  What doesn’t impact hormones?  Hot peppers impact hormones and I’m still going to eat them.  BUT and this is a big one.  Is it IF that is affecting the hormones?  When people ride this gender specific wave it makes me cringe and it’s not that I don’t agree that it is an important discussion, but when I speak to people about this I find something very interesting.  Every time I find that it has little to do with intermittent fasting and a whole lot to do with calorie restriction.  I’ve not spoken to one person who has complained about amenorrhea that didn’t also admit that with their IF, they also were eating 500 to 700 calories less than before they started IF.  GUESS what causes amenorrhea?  Did you get calorie restriction?

Here is one such study that speaks to the horrors of intermittent fasting related to Functional hypothalamic amenorrhea which is a non-organic, reversible disorder in which the impairment of gonadotropin-releasing hormone (GnRH) pulsatile secretion plays a key role. There are main three types of FHA: stress-related amenorrhea, weight loss-related amenorrhea and exercise-related amenorrhea. (4)  Did you miss the part where it is IF’s fault?  Me too, must have been subtle.

And another study speaking to secondary amenorrhea and the stakes are getting higher.  When these hormones cannot communicate with the ovaries, you run the risk of irregular periods, infertility, poor bone health and other health effects (5)  Still nothing about IF, but plenty about calorie restriction.

I did find one study that did allude to IF causing similar reproductive issues in female rats as did the 20% calorie restrictive diet, however the study stated the following:  Forty-seven male and 47 female rats were fed 20% Calorie Restrictive Diet, 40% Calorie Restrictive Diet; IF (alternate day fasting); and high-fat/high-glucose (HFG). Control, CR, and IF groups received food pellets that contained 19% protein, 64% carbohydrates, and 17% fat.   This food had a caloric density of 3.774 cal/g and a glycemic load per kilogram of 442. Food was provided (or removed in the IF group) at 1000 h daily. (6)  This study left me grossly wanting, IF?  ADF?  How long was the period of fasting?  How many calories were consumed on the feeding day? And all of the conclusions spoke to the findings being related to calorie restriction.  Further, this study was conducted to elucidate the dangers of anorexia nervosa.

And this mess right here

This one I find very telling.  The abundance of “science” that is being used to cast a shadow of doubt on intermittent fasting are studies performed, first of all on rats, and secondly in direct relation to studies on the dangers of anorexia nervosa.  Further, all of the studies I have researched have spoken to alternate day fasting and not daily IF with a window of 16 X 8.

It may help to understand how the individual factors such as metabolic fuel, sex hormones, leptin, NPY and kisspeptin act as neuroendocrine regulators to link reproductive dysfunction to the perturbations in energy balance. Changes in the expression level of these molecules adversely affected GnRH expression and its release from the ME region of hypothalamus in both the male and female rats on IF-DR regimen, thus supporting the proposed hypothesis of a central link between reproduction and energy status   It may be suggested that the reduced leptin levels in IF-DR animals conveys the nutritional signal to arcuate nucleus of hypothalamus through the metabolic sensors such as NPY and kisspeptin, and further the alterations observed in their expression may be important factors in disrupting the function of HPG axis in response to negative energy balance. Moreover, the current results suggests that the GnRH neurons which occupy a master position in HPG axis, become target of many central and peripheral origin metabolic regulators directly or indirectly thus compromising reproductive functions in the face of energy status. The current data may help to understand the clinical basis of nutritional infertility observed in patients of anorexia nervosa and hypothalamic amenorrhea due to metabolic stress, excessive exercise, undernutrition etc. (7).  Are we seeing a theme here?  If you have read this far and your eyes are not rolling to the back of your head, it doesn’t take a scientist to figure out the common theme is calorie restriction or as some call it energy imbalance, undernutrition.

So what if you are not malnourished, what if you’re not restricting calories, what if you’re even overweight?

Diet and reproduction have a mutually benefiting relationship. Overweight and obesity in early adulthood appear to increase the risk of menstrual problems, hypertension in pregnancy, and subfertility.  Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women.  The clinical manifestation of PCOS varies from a mild menstrual disorder to severe disturbance of reproductive and metabolic functions. A recent study conducted on women with PCOS revealed that fasting can reduce the chronic sympathetic over activity in PCOS. This, in turn, will reduce stress neurohormone levels and ensure the physical and mental health.   Lifestyle change is the first-line treatment in an evidence-based approach in the management of the majority of PCOS women who are overweight.  Studies reveal that as little as 5–10% weight loss has significant clinical benefits improving psychological outcomes, reproductive features (menstrual cyclicity, ovulation, and fertility).  This bespeaks the role that fasting can play in enhancing women’s’ reproductive health. (8)

So hey, I am the last person to tell you how to work your program.  And I don’t do the mansplain thing, if you met me your first thought would never be wow look at that super masculine dude, it would be more like, “nice purse, where did you get that scarf?”  I am a researcher and bullshit detector.  If new evidence emerges I would be happy to pick it apart.  Peace….jj