daily eating window

A Guide to Having a Daily Eating Window

It has been well researched and documented that time-restricted eating has many benefits, such as: 

  • Increasing ketones
  • Increasing mitochondrial
  • health and stress resistance
  • Increasing antioxidant profile
  • Increasing autophagy (Programme cell clearance)
  • Increasing DNA repair
  • Decreasing glycogen (glucose stores)
  • Decreasing insulin
  • Decreasing mTOR
  • Decreasing protein synthesis

In fact, one study in ‘The Journal of Nutrition, Health and Agingin 2018 showed that in obese individuals there was dramatic metabolic improvement despite what they ate, given that it was in an 8-hour window. 

That’s not to say that you can or should eat what you want when you are fasting and, in fact, fasting with ‘intention’ can be more beneficial and effective than simply ‘skipping’ meals.

There are some cases whereby a person should not practise fasting, such as: 

  • If you have a known eating disorder, you must check with your GP before you try this way of eating.
  • Pregnancy and nursing is not the time to fast; you need more calories, nourishment and snacking while pregnant or breastfeeding.
  • Type 1 and 2 diabetics can achieve great results but check with your GP first.
  • People with thyroid issues don’t respond well to one meal a day because they need to ensure they have enough calories p/d.

If you are able to incorporate time-restricted eating within an 8–12-hour period then it can: 

Increasing ketones is also an important part of fasting and this begins to occur after 12 hours. Ketones are the preferred fuel source for our mitochondria which are the powerhouses of our cells. Our brain will also like to fuel on 50% glucose and 50% ketones if possible. Fasting can also increase autophagy which is the ‘cleaning up’ of the cells. A healthy microbiome may also help us in the fasted state, but we are all individuals and our microbiomes may play this out differently. 

Essentially, when we’re eating we are raising blood sugar, and so by waiting 1 hour or more before having breakfast and eating dinner 1-2 hours earlier, we’re limiting blood sugar spikes. It may be hard to start with, and everyone has their own fasting lifestyle; some people find that 12:12 is perfectly fine for them, while others thrive on a 16:8 window. 

Here are some of the metabolic processes that come into play after a certain number of hours: 

  • 12-16 hours daily – fat burning, ketones, growth hormones, increased testosterone.
  • 17 hours – autophagy kicks in, cells become more efficient because there is no food or nutrients; cell clean out; clear dysfunctional cells.
  • 36 hours – weight loss really kicks in, glucose mobilises from the liver.
  • 48 hours – dopamine systems may be reset – new dopamine receptor sites will be reformed – you may enjoy food and other things in your life more.
  • 72 hours – immune system and stem cells may be reset.

I’m only advocating a daily time-restricted eating window and not the above fasts. 

What you can and can’t have: 

  • Coffee will be fine for most people: the way to check would be to perform a blood glucose test to check whether caffeine spikes your blood sugar.
  • But stick to black coffee.
  • Consider adding MCT oil as this will keep you satiated and may enhance ketone production.
  • Ghee may also be fine but, again, best to check if it works for you with a test.
  • Electrolytes are a good option to add to water.
  • Fasted snacks include bone broth. Full fat foods don’t spike blood sugar, but they do kill hunger. Keto Cups are a full fat product.

What else do you need to know?

  • Anything that raises blood glucose to over 5 points will break a fast.
  • Protein will break a fast.
  • Muscle has more insulin receptors in it so it’s very important as we age.
  • Fasting creates a great new environment for the new bacteria to grow.
  • Polyphenol, probiotic and prebiotic rich foods will feed the new garden.
  • Fat will stop the desire to overeat once you start eating.

What About Women and Fasting? 

There are three phases to fertility, and we should be mindful of this when we come to fasting/eating windows. 

1 – Fertile phase – fasting can be very good during this phase.

2 – Perimenopausal phase (up to a 10 year journey) and includes weight issues, mood issues and sleep issues.  

3 – Menopausal phase – sex hormones are now being handled by the adrenal glands, so if the adrenals have been in high performance mode, the adrenals may be overloaded and so when the sex hormones come to rest on the adrenals, this is what can cause worsening of perimenopausal symptoms. 

To get the most from fasting, begin by tracking your cycle because oestrogen likes keto, fasting and exercise but progesterone needs nourishment, rest, more complex carbs. So, the front half of your cycle is good for fasting, but the back half is not good for fasting because oestrogen and progesterone are different. 

Progesterone doesn’t do well with fasting as it will decrease progesterone which may lead to more hair loss, weight gain, trouble sleeping and anxiety. 

If cortisol is high then progesterone goes low, so stressors (fasting and high intensity exercise) isn’t a good idea in the run up to our periods. Women are also more insulin-resistant in the week before periods as progesterone needs glucose to thrive.

So this is why progesterone makes a woman crave glucose, and crave chocolate too for the magnesium, so we should learn to slow down to make less cortisol so that progesterone can make its show. Oestrogen on the other hand will thrive when burning glucose, doing cardio, HIIT, fasting and low carb living. 

Women often push through this phase when they shouldn’t – it’s a time to rest. But avoid refined carbs and stick with nature’s carbs which are natural and complex like sweet potatoes and oats. 

Protein is also so important for women, aiming for 60g p/d, at least to fire up the amino acids for muscle growth – ideally 1g per pound of body weight, and this can be hard with fasting. 

Men’s hormones are different as they are on a 24-hour cycle, but as we know, women have three hormones on a 28–30-day period. Testosterone and fasting work well together, which may be why men seem to find fasting for long easier, as women only get testosterone in small parts of their cycle. 

For further insights and questions feel free to contact Layla Gordon.

Reference: Pelz, M. (2022) Fast like a girl: A woman’s guide to using the healing power of fasting to burn fat, boost energy, and balance hormones. Carlsbad, CA: Hay House.