Is intermittent fastingbad for women?
3 min
Intermittent Fasting (IF): the practice of going without food for prolonged periods of time, is known to do some amazing things for your body: improved weight loss, decelerated aging and better heart health – if you’re a man that is. Women haven’t been so lucky.
Background
Every time you eat, your body releases insulin (see here). In today’s world, we eat more frequently than we should, driving insulin levels up. When this happens, you store more fat and risk disorders such as type two diabetes and cancer. By contrast, when you practice intermittent fasting (IF), your body is in a fasted state for anywhere between sixteen to forty-eight hours, therefore releasing less insulin.
There are several ways to practice intermittent fasting, some of the most popular include:
- The 16/8 Method: Fast for 16 hours each day
- The 5:2 Diet: Fast for 2 days per week
- Eat-Stop-Eat: Do a 24-hour fast, once or twice a week
(For more information see: healthline.com)
In a fasted state, your body also has the time and space to perform a key biological process known as autophagy: the repair and recycling of damaged cells. Autophagy improves your memory and focus, reduces your risk of cardiovascular disease, restores your skin cells (thus slows down the rate of aging), and puts you in an all-around better mood. Amazing stuff.
The female case against IF
Unfortunately, IF for women doesn’t bode so well when compared to men. Reported side effects include:
- Irregular periods
- Early menopause
- Metabolic disorders
- Sleeplessness
- Anxiety
- Brain fog
(Source: https://www.precisionnutrition.com/intermittent-fasting-women)
Why is this? Because female hormones do not respond well to calorie restriction. For instance, it is well established that the menstrual cycle and fertility hormones are impacted by malnutrition. Women who are underweight are at greater risk of infertility. That said, it’s not entirely clear why female hormones reject calorie restriction more than male hormones. The most plausible explanation relates to kisspeptin: a protein produced by the hypothalamus region of your brain.
In women, kisspeptin controls the hormones which regulate ovulation: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In men, it controls the production of testosterone. Since women produce more kisspeptin than men, theoretically this is one reason why they are more sensitive to caloric changes from IF. Studies support this notion. In the case of female mice placed on a calorie-restricted diet, they experienced a dip in kisspeptin levels and subsequently lower fertility rates.
And if you’re a woman with a weight loss goal, another study linked kisspeptin to obesity and metabolic disorders. Women are extremely sensitive to signals of starvation, and if the body senses that it is being starved, it will ramp up production of the hunger hormones leptin and ghrelin
The stress of intermittent fasting impacts women’s hormones disproportionately to what men deal with. Females should consider the risk factors outlined here and always consult their health practitioner in the first instance.
As always, pushing for health.
Photo Credit: www.musclemonsters.com
Hey Sukhey! Always nice to read your input. I’m curious though – if the root issue is caloric restriction, what does that have to do with intermittent fasting? There are definitely a lot of other experiments that would be worthwhile to conduct to see how women respond to each.
1) Eating at a caloric deficit but spacing meals out throughout the entire day (deficit, no fast)
2) Eating at a caloric deficit but limiting meals to certain times (deficit, fast)
3) Eating at a caloric surplus with meals spaced out (surplus, no fast)
4) Eating at a caloric surplus via only one or two very large meals in a day (surplus, fast)
Additionally – I wonder if these women were eating enough good fats which can directly affect estrogen levels in the blood.
And, anecdotally, I greatly prefer intermittent fasting. I always found it difficult to eat breakfast, I’d prefer to just drink coffee or tea, and cold water in the morning. I wouldn’t typically get hungry til the afternoon. It was a nice surprise to learn of IF and see some science that backed my habits. I had felt my preferred way of eating was ‘wrong’ due to being constantly told to eat 6 smalls a day or the typical 3 square meals a day. I feel better eating a really big lunch, a mid-day snack, then a small-ish dinner. It’s what has worked for me! But – that’s just personal preference 🙂
Hey Christina,
Thank you for the thoughtful reply. IF simulates calorie restriction because your body is not eating as frequently (foregoing opportunities to intake calories). Theoretically, during the eating window you can’t compete with someone who’s eating throughout the day… net effect restricted calories.
The effects of IF and Fat intake – I couldn’t find any studies on this. But there is certainly a good argument there, and I myself, since going low carb / high fat, have definitely felt satiated for longer periods of time.
All the IF science I could find, observed marked differences in kisspeptin levels in females who undertook IF.
That said, it’s not doom and gloom for for all women, which i’m glad to see includes you. It’s just another risk factor to be aware of.
Hope I shon some light.