“We all breathe oxygen, get stronger and fitter when we work out, use the same neurotransmitters, and produce the same hormones. The biological basics are identical”
This mornings read is from Mark Sisson's blog, Mark's Daily Apple
Below are some of the main points I found interesting:
Fasting As Hormetic Stressor and the Influence of Biological Sex
Men and women both need to enter a “fasted” state in order to burn body fat. This should go without saying, but regularly undergoing periods where you’re not inserting calories into your mouth is an absolute requirement for weight loss and basic health, no matter your sex.
By definition, a fast is a hormetic stressor—a stressful input (no food) that in the right dose triggers an adaptive response that makes us stronger and healthier.
One study found that while IF [Intermittent Fasting] improved insulin sensitivity in male subjects, female subjects saw no such improvement. In fact, the glucose tolerance of fasting women actually worsened.
Later, both obese men and women dropped body fat, body weight, blood pressure, total cholesterol, LDL cholesterol, and triglyercides on a fasting regimen. These people were obese, however, and perimenopausal women were excluded from the study, so the results may not apply to leaner people or women in the perimenopausal window
What About the Effects of Training While Fasted?
Only men showed greater skeletal muscle adaptations when fasted. Women had better muscle adaptations when fed.
How About Autophagy?
One of the main benefits of intermittent fasting is an increase in autophagy, the process by which our body clears out cellular debris and repairs damaged cellular structures like mitochondria. A decrease in autophagy is usually linked to increased aging; an increase in autophagy tends to stave off the ravages of aging. Fasting-induced autophagy is usually a good thing
Only that might not be true for both sexes; another study shows how while “male neurons” respond to starvation as we’d expect—by undergoing autophagy—”female neurons” respond by resisting autophagy.
My Conclusion…For Now
As it stands right now, I’d be inclined to agree that pre-menopausal (and perhaps peri-menopausal) women are more likely to have poor—or at least different—experiences with intermittent fasting (at least as a weight loss tool). That said, it appears to be a potentially gender-neutral therapeutic tool for chemotherapy, cancer, and age-related neurodegeneration patients
So, Who Should and Who Shouldn’t Consider Fasting?
“If you haven’t satisfied the usual IF [Intermittent Fasting] “pre-reqs,” like being fat-adapted, getting good and sufficient sleep, minimizing or mitigating stress, and exercising well (not too much and not too little), you should not fast”
I would also caution against the already lean, already calorie-restricted woman jumping headfirst into IF. I mean, fasting is ultimately sending a message of scarcity to your body. That’s a powerful message that can get a powerful response from our bodies. If you’re already lean (which, depending on the degree of leanness, arguably sends a message of scarcity) and restricting calories (which definitely sends a message of scarcity), the response to fasting can be a little too powerful
I’d also say that daily fasts, a la 16/8 or even 14/10, run the risk of becoming chronic stressors and should be approached with caution by women
Some Warning Signs To Watch For
- Weight Gain (especially in the midsection)
- Insomnia
- Muscle Loss or Reduced Performance In the Gym—It’s perfectly reasonable to suffer in the gym on fasting days, but watch out for persistent strength losses. If your fitness and strength levels are consistently trending downward, fasting may not work for you.
- Infertility
- Loss Of Your Period—Skip meals, not menstrual cycles.
- Excessive Hunger—Feeling peckish is good for everyone and makes food taste better; constant satiation is a trap of modernity. But you shouldn’t be ravenous. Thoughts of food shouldn’t consume you.
Some Thoughts For Women Who Want to Fast
Instead of aiming for the longest fast you can tolerate, aim for the shortest fast that gives results
I’ve never prescribed intermittent fasting as a requisite piece of the Primal lifestyle, but rather as an elective addition, a personal choice—only as a potentially therapeutic strategy that each individual must test for him or herself
These are only some highlighted points, please read the full post if you want to find out more: https://www.marksdailyapple.com/women-and-intermittent-fasting/?awt_l=5qx.z&awt_m=JxpuXiEUwhWvYa&utm_source=mda_newsletter&utm_campaign=mda_newsletter_051618&utm_medium=button1
I get asked relatively often about Intermittent Fasting for women, and my response is always the same. Make sure you are sufficiently fat adapted and following the guidlines that people like Mark outline.
Fasting can either be the single most beneficial or descrtuvtive stressor you place on your body.
Always complete fasts with caution and under strict supervision from doctors and experts -- I am not anyone of these but my job is to share my findings. As a male, fasting and Intermittent Fasting has changed the way I diet and train. It's a powerful tool -- but, like Mark said, I don't do it chronically. I listen to my body. When I feel I can go longer, I do. When I feel like shit. I EAT!!!
Hope this helps.
Happy IF, Josh