Let’s talk weight loss, and more specifically intermittent fasting. (If you've landed here via my post on Facebook or Instagram then skip ahead to "What is Circadian Fasting?").
There are different styles of intermittent fasting but the one I see most commonly in clinic is people skipping breakfast and having their “eating window” (the time during which they will eat their meals) later in the day.
Hardcore Intermittent Fasters will tell you that breakfast is no longer considered the most important meal of the day.
They also claim that it’s in fact healthier to skip breakfast.
You’ll not only lose weight, but you’ll be more focused, less inflamed, and will become smarter and fart rainbows 🌈
If you can’t tell, I have some issues with the messaging around intermittent fasting.
Like a lot of things, there’s been substantial hype around it.
Is it good for some people? Yes ✅
Does that mean it’s good for everyone? No ❌
Here are the big issues with Intermittent Fasting:
1. The initial studies that showed the benefits were conducted (yet again) on men and not women. The physiology of the biological male and biological female is very different.
Subsequent studies that have included both men and women have shown that while intermittent fasting may be beneficial for men and post-menopausal women (keyword: *post*, meaning after not during), it can have negative effects on blood sugar and hormones for those individuals still experiencing a menstrual cycle.
Intermittent fasting can disrupt estrogen balance and have a knock on effect on adrenal and thyroid hormones.
2. When intermittent fasting, people are also more likely to start their day drinking black coffee on an empty stomach.
Those of you who’ve been following me for a while now will know I once suggested to the internet that to avoid screwing with your stress hormone levels and to protect the function of your stomach it was better to drink coffee 60-90 minutes after waking up, and preferably after (or with) your breakfast.
Some of the internet got more than a little cross with me for such a suggestion, but I stand by it.
3. According to Chinese medicine theory (I say that so much it could be a drinking game 🤭) the digestive system is most active between 7AM-9AM making breakfast time the most optimal time of the day to eat to support digestion.
Within the framework that I practice, skipping breakfast is not advised.
The problem is: with menopause comes weight gain. Suddenly women find themselves gaining weight around their abdomen and bra strap line overnight.
And very often Fitfluencers on the internet will tell you intermittent fasting is going to melt away menopausal belly fat like magic.
But while shifting your "eating window" (imagine I'm doing that thing in the air with my fingers while I say that 🤭) back to later in the day may have some benefits for biological men and post-menopausal women, for biological females still experiencing menstruation - even those in peri-menopause - any benefits to intermittent fasting could be outweighed by the negative impacts.
However, there are benefits to giving your body a break from constantly digesting food - and that includes for pre-menopausal and peri-menopausal women.
If you want to experience these benefits without messing up your hormones then you might be better off trying CIRCADIAN FASTING.
WHAT IS CIRCADIAN FASTING?
Circadian fasting is intermittent fasting’s less sexy friend.
I say that because it requires you to shift your eating window forward - meaning you eat breakfast but skip dinner (or have a light meal a lot earlier than you’re probably used to).
This is less fun. Let’s discuss.
Most people claim they aren’t hungry in the morning anyway. Chinese Medicine philosophy tells us this is due to imbalanced digestive function. Additionally our modern understanding of the body suggests that if you aren't hungry in the morning this is probably due to an impaired functioning of your adrenal system.
Think about it, you should be hungry at breakfast because ideally you just went 10+ hours without eating.
But even if you're adrenals are tip top and you do find yourself hungry in the morning, for a lot of people it’s still easier to squash your appetite with caffeine (when we’re all time poor and rushing out of the house anyway) than it is to have the discipline to eat your evening meal before 7PM and then avoid snacking on the couch until 10PM (no judgement, we’ve all done it).
The evening meal is also a pretty social event, either among the family or going out with friends. A lot of the time people are only just meeting up for pre-dinner drinks or getting home from work at 6PM, so circadian fasting can require some adjustment at best and missing out on fun stuff at worst.
I get that I’m not really selling it here, so please read below to learn the BENEFITS of circadian fasting.
WHAT IS THE CIRCADIAN RHYTHM?
Your circadian rhythm is an internal body clock. It’s aligned to the natural rhythm of day and night and is also sometimes called the sleep-wake cycle.
It covers many aspects of the functioning of your body, from your temperature to blood pressure, hormone secretion, co-ordination, strength, reaction time, as well as memory and digestive function.
Ever wondered why you don’t get up in the night to poop? That’s thanks to your circadian rhythm. The function of your bowel is suppressed at night. This is because your very clever body knows there are far more important things to do at night.
Namely, resting and repairing.
Which brings us to the topic at hand:
WHAT ARE THE BENEFITS OF CIRCADIAN FASTING?
A lot of it comes down to the role of two key hormones: insulin and melatonin.
When you eat, your pancreas secretes a hormone called insulin to help regulate your blood sugar.
If you have a friend who is a diabetic, you will know that proper insulin secretion and absorption is literally a matter of life and death.
Your body is designed to produce insulin during the day, when you’re awake and eating food for energy.
Melatonin on the other hand is a hormone that is produced by your brain in response to darkness. Melatonin promotes sleepiness and your body starts to produce it a few hours before bedtime.
But melatonin has other functions.
Hormones are the chemical messengers of the body – they run around your bloodstream delivering instructions. In addition to making you feel drowsy, melatonin binds itself to receptors in the pancreas and in so doing delivers a message that it is time to temporarily shut down the production of insulin overnight.*
When you eat in the evening, you’re asking your body to produce insulin. Not only is it not an optimum time for you produce insulin but thanks to melatonin binding to pancreatic receptors, it’s a task your pancreas will have an impaired ability to perform.
Over the longer term, this can lead to blood sugar and insulin dysregulation, which can lead to diabetes, weight gain and obesity, and other metabolic problems that can result negative health outcomes.
It’s also worth noting that while insulin resistance makes it easier to gain weight, it isn’t always accompanied by weight gain. Which means you could still have insulin resistance (and be susceptible to all the negative health outcomes that go along with it) without putting on weight/being overweight.
When you stop eating earlier in the evening, you’re helping your body by freeing it up to rest and repair.
It can focus on popping off cells that aren’t behaving as they should (left unchecked these bad boys can become cancerous), reducing inflammation, healing damage, fighting illnesses, and slowing your heart rate to take the pressure off your cardiovascular system.
A 12 hour fasting window is a good start and having dinner by 7pm and breakfast at or after 7am is pretty manageable for most people.
Once you’ve established a routine you can try having an earlier meal a couple of nights a week to extend your fasting window to 14 or 15 hours.
Of course, eating this way delivers the best benefits when you combine it with other habits that support a healthy circadian rhythm. This includes going to bed and waking up at the same time each day (bed around 10-11pm and waking around 6-7am is a good ballpark for most people), eating before 10am, getting sunlight into your eyes in the morning (pre midday) and spending time in nature.
If you’re a woman and you’ve been considering intermittent fasting for weight loss but you haven't gone through menopause yet (you have to go 12 months without a period to be diagnosed as having gone through menopause), give circadian fasting a try. You can enjoy all the same benefits without the potential drawbacks.
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