Fasting and Hormones..
What’s the link between fasting and hormones?
All types of fasting have become more and more popular the last few years. Personally, I started doing small seasonal fasts over 30 years ago. I stopped eating after Friday lunch and then only drank water or herb teas until Sunday evening, when I would have a vegetable soup and some kind of salad. I always did it on a weekend when I could rest, sleep, read and generally take it easy. And I always felt amazing afterwards. Then once I had children I just couldn’t find the time to dedicate a whole weekend to resting so fasting went out the window for several years. But with the surge of research into Intermittent Fasting I’ve been experimenting again with both Time Restricted Eating and juice fasts, and like before, I enjoy it.
But, it’s not for everyone, and many people will have different reactions depending on their Age and Stage. It’s important to know if fasting is right for you, so we’ve set out a few simple guidelines
What Does Fasting Actually Mean?
Fasting is when we restrict the amount we eat, or the times that we eat. So it’s either cutting down the calories, or cutting down the hours when we consume food - or both!
Water fasts, or juice and soup fasts have always been popular - that’s when you either drink only water for 24 hours or a few days, or consume just juices and soups.
Then there’s Intermittent Fasting. This is more about time than calories. It means you eat intermittently. Some people do it by leaving a long break between the last meal of the day and the first one the next morning - up to 16 hours in some cases. Others do it by restricting their calories on 2 days a week. That’s the 5:2 diet, where you eat normally on 5 days of the week and severely restrict your calories on 2 days a week.
So what’s the link with hormones?
Well, as human beings, we evolved to eat regularly. And in really ancient times, unintentional fasting could mean you are entering a famine. So if you go over 36 hours or so, the body can start to think it’s in trouble.
For women of menstruating age, reduced food intake can lead to a hormonal response. Studies have shown that women undergoing a 2 or 3 day water fast in the first phase of their menstrual cycle before ovulation (the follicular phase) will be more likely to stop ovulating that month, especially if they are normal weight or underweight. This effect was not so pronounced if they were overweight.
But, if the same women undertook a 2 or 3 day water fast in the luteal phase (the second half of the cycle after ovulation), it could help relieve the symptoms of PMS, improve their heart rate variability and it didn’t affect ovulation the following month.
It makes sense in evolutionary terms. If the body thinks that now may not be a good time to get pregnant because there’s a famine coming, then it switches off ovulation until it feels safe again.
So if you are trying to get pregnant, it’s not a good time to fast because of these nutritional sensors in the brain and body.
And for menstruating women who are not trying to get pregnant, you will get more benefits from fasting in the later half of your monthly cycle.
What about the stress hormones?
Again, remember that the body will interpret loss of food as a stressor. So if you’re already suffering from high cortisol levels (peri and menopausal women, beware!), now may not be the best time to go on a prolonged fast. Time Restricted Eating may work better for you. But remember that the both the digestive system and insulin sensitivity work better earlier in the day. So instead of delaying breakfast, you may get better results from having a good breakfast, late lunch and skipping dinner.
In conclusion, fasting can be of great health benefit to the body, but make sure you take your hormones into account to achieve the best results.