There is a big problem when it comes to exercise and nutrition prescription for women. Most of the studies that are used as evidence for prescription in the media were studies done on men—not women.
And certainly not active women.
There are so many different sex differences between men and women and further to that women in different stages and phases of life.
A study conducted on trained men between the ages of 19-24 will have a very different outcome than a woman who’s perimenopause.
The issue with the research is that it’s expensive to study women because of hormone fluctuations and finding consistency (men don’t have this problem—it’s easier). And even a female who’s the same age can still have very different functioning bodies depending on what their life is like (for example a 28 day cycle compared to a 38 day cycle).
When it comes to nutrition, especially, we MUST be discerning with the information we are taking in.
How does this apply to me?
Does this apply to me?
Does this fit my life function?
Intermittent fasting is a current diet trend (I’m not going to go into the rabbit hole of the problem with diet culture—today is just about giving you information and you making informed decisions for yourself). It’s quite a buzz word(s). There needs to be a BIG FAT CAVEAT here that acknowledges IF for medical reasons in diseased humans but if you are consider IF and it is not because of a diagnosed health reason, this article is for you.
In the media intermittent fasting (IF) is often revered as this incredible rejuvenating diet. It’s health benefits are spoken of. BUT the problem is that most research done on IF, like I mentioned before, has not been conducted on athletic populations and especially not athletic women (athletic doesn’t mean competitive sport, it means to be physically active). The media reports IF to give wonderful health benefits like:
Your body burning more fat
Having a longer life
Improving blood sugar
Cleansing the body
But what is not reported in the media is the very big difference between men and women with IF.
First just some examples of the different kinds of IF:
Mosely (5:2, fast 800)
Some of the main sex differences that happen on a physiological level
1. Kisspeptin is a neuropeptide that is responsible for reproduction, puberty, well-functioning adrenals and endocrine system. It is the feedback mechanism for Gonadotropin-releasing hormone (GnRH), which is responsible for the follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which allows us to have a menstrual cycle and a rocking endocrine system. Kisspeptin is more sensitive to ups and downs of the nervous system and lack of calories so can be the precursor to menstrual cycle dysfunction. Meaning, being in a fasted state and not eating enough leads to endocrine dysfunction because Kisspeptin isn’t able to do its job.
This is why educating my clients on the importance of eating enough is so important. You can still change your body composition when you are well fed. Not eating does not equate fat loss.
2. IF is parasympathetic in men but sympathetic in women. Men are able to reap the cognitive focus and clarity that IF presents in the media. In women, however, it is a sympathetic response: anxious, brain fog, depression, elevated heart rate. This is not enough calories contributes to a much higher sympathetic drive in the body. Again, another reason why the research is irrelevant to women.
3. Autophagy is your body’s ability to kind of clean itself up, to regenerate cells and get rid of others. IF can help to encourage this in men, but it has minimal effect in women.
4. There is an increase visceral fat in women. This is the fat around essential organs that increases cardiovascular risks and is harder to shift.
5. No improvement in glucose control in women.
So as you can see, for women there are many irrelevant and negative effects compared to men.
From a health standpoint, for women, it's not relvant.
Now, if you were still interested in it you could do more of an intentional fast which would contribute to perhaps getting some of the autophagy benefits. This would be stopping eating after dinner then not eating till the morning—which is probably what you do anyway. This would give you the rest and digest response, give your digestive system a break overnight without intentionally doing a fast. It might look like finishing dinner at 7pm then eating breakfast at 7am.
Active women and IF
There was a study that was done on endurance athletes that looked at the timing of when women ate during the day.
In the study there were women that ate in morning, exercised then didn’t eat again until night, even though they ate enough calories for the day but because they spent most of the day in a catabolic state they ended up with reproductive abnormalities like irregular cycles. This was because of the inability for kisspeptin to do its job through lack of calories (like discussed above).
This is so relevant for many women who are busy. Does this sound familiar?
Rush to the gym in the morning, do your workout (it’s usually intense because gotta go harder if it’s shorter, right?). You don’t have time to cool down properly but have to shower, get dressed and get to work. There’s definitely no time for breakfast in there so you’re not eating until much later—if and when you remember!
If you are having something small in the morning, training then going into life, being busy, and don’t eat until dinner, this can contribute to low energy availability (lack of calories = hormone dysfunction) and the ill effects of IF in an unintentional way!
The longer you stay in a catabolic state the more disruption there will be to the endocrine system and your metabolic rate.
I often hear women saying they are fasting but I always want to question: what actually are you doing this for? Being in a catabolic state (whether it be intentional due to an IF protocol or unintentional because you’re busy) really can contribute to thyroid and endocrine dysfunction. This can lead to fatigue, brain fog mood disruption and putting on body fat (even if you’re trying so hard to get it off).
I urge you to really consider why you’re choosing to do IF and if it is right for your life function.
The other thing to consider is how exercise fits into this.
Exercise puts us in a fasted state itself because you’re using fuel.
You’re creating stress and your body is responding to that stress. You are getting into a bit of autophagy (remember, this is the cleaning up of your body) because your body is cleaning up debris from the metabolic response from exercise.
Exercise helps you to regulate blood sugar control and insulin response.
Exercise helps you create more mitochondria.
It helps to lose body fat and create more muscle.
All the things that are reported as benefits in the IF literature are the same as exercise, right?
Can you instead fuel yourself well and train in a way that is right for you and your life with the right dose response to reap all these benefits?
Because exercise will do this.
Muscle protein synthesis (body repairing), body composition, anaerobic and aerobic adaptation are so much better when a woman goes to a training session in a fed state. For men there’s no real difference. Men respond differently to catabolic state and the stress of fewer calories compared to women (as you now know).
The bottom line is how you are fueling yourself to create that Kisspeptin response and how your endocrine system is functioning.
SO! Now that you have that information in your tool box, what are you going to do?
Being well fed and following a purposeful training program that has the appropriate amount of intensity is going to be the ticket to feeling all the things that IF is sold to you as.
If this sounds like something you need in your life and you want to eat and move in a way that makes sense you can get onto the waitlist for The Bold Collective here.