27/02/2026
Is extended overnight ‘fasting’ affecting your bone density? 🤔 Very interesting 🧐
And while we're talking all things 'peri' you might recall I said during this period our bones adopt the 'brace position' - you know before you crash?!😰...unless...we know how to preserve properly
PTH is an acute responder to any dip in Calcium
Within seconds it surges
Within mins to increase Calcium’s paracellular uptake, the GIT becomes ‘leaky'
Within 1-3hrs the bones have been tapped
PTH peaks first thing in the morning partly in response to an endogenous circadian rhythm but also because, quite simply, we’ve been fasting and no new Calcium has come into the system. So what if we extend our overnight fasting? The PTH gets higher and stays up for longer, resulting in more negative impact on the bones. And SO many women have embraced TRE or at least extended overnight fasting – for good reasons, right? But what about the impact this is having on one of the most modifiable risk factors for osteoporosis? I’ve just had this conversation again with yet another woman. We had sequential PTH measures one at 7.20am (PTH 4.7 pmol/L), one at 8.30am (PTH 5.3 pmol/L) – both are too high for optimal BMD preservation. But the real issue is she doesn’t actually eat her breakfast usually until about 10am. This translates to a very long period of exposure not only to high PTH but peak cortisol concentrations to boot. She was taking Calcium (and doing everything else, including targeted resistance training) but I had to tweak the timing of her first dose… and then we had to try and reconcile this with her TRE.
For a patient like this with this tendency of the PTH to push up too high – the 1st dose of Calcium must be within 2hrs of waking
Compared with other supplements it’s an easy one to take (not a gastric irritant like some) & with just 50-100ml of whatever milk or substitute you prefer is an easy ask before hitting the gym or the pavement or the desk! Alternatively, of course, if someone is not adhering extended overnight fasting, your just bring breakfast forward & ensure it’s a calcium rich choice. This is what I mean when I say science drives the most successful prescribing…not the bad most basic of nutritional science that SCREAMS, ”Deliver Ca to those bones like a concrete-mixer. Just pour it in!”
Nope.
The exceptional science that reveals the real nuance of how nutrients work and how then to employ them to achieve the very best results.
And if now you’re rushing to reach for Calcium but have questions about best form and dose, duration and combinations…and are hungry to experience the same level of confidence prescribing all the other nutrients to boot…well might I suggest 🤓 you look into undertaking our Nutrient Prescribers' Program?
Or if you now feel an urgent need to polish your parathyroid knowledge, assessment, understanding, management...then check out these two Update un Under 30 episodes
🎧Working with Micromanaged Minerals https://rachelarthur.com.au/content/working-with-micromanaged-minerals/
🎧and this one one what gets missed and mistaken for 'just' (peri)menopause including unmasking of hyperparathyroidism which comes with a great clinical tool
https://rachelarthur.com.au/content/menopause-missed-misdiagnoses-part-1/
