1. Get the Diabetes Forum App for your phone - available on iOS and Android.
    Dismiss Notice
  2. Guest, we'd love to know what you think about the forum! Take the Diabetes Forum Survey 2022 »
    Dismiss Notice
  3. Diabetes Forum should not be used in an emergency and does not replace your healthcare professional relationship. Posts can be seen by the public.
    Dismiss Notice
Dismiss Notice
Find support, ask questions and share your experiences. Join the community »

How Low is Too Low on Extended Fast?

Discussion in 'Low-carb Diet Forum' started by droog, Jul 12, 2020.

  1. droog

    droog Type 2 · Member

    Messages:
    10
    Likes Received:
    0
    Trophy Points:
    41
    I am a 55 yo male, type 2 (diag 2012) on Metformin only (2000mg extended release). Last two A1C: 30.1 mmol/mol (4.9%). Current weight 210 down from 400+ a few years ago. No complications. Diet: VLCHF, < 20gr carb daily. Well most days. ;)

    Fasting Regime: Water, tea, black coffee, vitamins & salts only.

    After 3-4 days of continuous fasting, I am in deep purple ketosis and my blood sugar typically hovers around 3.6 mmol/l (65 mg/dl). But occasionally has dipped down around 3.0 mmol/l (55 mg/dl), confirmed by two tests 10 minutes apart. When it is in the 50's I definitely feel low energy. Having blood sugar in the 50's concerns me and I break my fast.

    However, I have read that some experiments from decades ago demonstrated that fasting patients in ketosis showed no ill effects from blood sugars below 20 following injection of insulin. While I am understandably skeptical about that...

    QUESTION: How low is too low when on an extended fast?

    Thank you.

    Oh, anyone have a reference to the study I mentioned, I can't find it?
     
    • Winner Winner x 1
  2. bulkbiker

    bulkbiker Type 2 · Oracle

    Messages:
    19,044
    Likes Received:
    12,608
    Trophy Points:
    298
    I've experienced 3's usually on day 3 of a fast but it soon goes back up to the low 4's for days 4-7 (never gone for more than 7 days)
    The study you are looking for is I believe one of George Cahills of the 1970's where they injected people in deep ketosis with insulin to drive their BS levels down to the 2's with apparently no ill effects.

    I'll see if I have a link to it.

    Edit to add I think its this one but I haven' t read through it to check! Sorry cooking dinner

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2441301/pdf/tacca00109-0225.pdf
     
  3. droog

    droog Type 2 · Member

    Messages:
    10
    Likes Received:
    0
    Trophy Points:
    41
    Bulkbiker,
    Thank you for your reply. I read through the document you posted. It didn't mention the experiment regarding inducing extremely low blood sugar during deep ketosis, but it was fascinating reading none the less.
    All the best,
    Droog
     
  4. LaoDan

    LaoDan Type 2 · Well-Known Member

    Messages:
    927
    Likes Received:
    594
    Trophy Points:
    153
    Great work on the weight loss!!!
     
  5. MarkMunday

    MarkMunday Type 1 · Well-Known Member

    Messages:
    421
    Likes Received:
    177
    Trophy Points:
    83
    Low blood glucose is a concern if there is excess insulin action driving it down. As you are not using insulin, IMO low blood glucose should only be a concern if you are not feeling well. The liver will supply enough glucose to keep you going until you end the fast..
     
    • Agree Agree x 1
  6. bulkbiker

    bulkbiker Type 2 · Oracle

    Messages:
    19,044
    Likes Received:
    12,608
    Trophy Points:
    298
    Sorry about that I'll have another dig around. It was mentioned in a Phinney video and I'm sure I have a link saved somewhere...
     
  7. bulkbiker

    bulkbiker Type 2 · Oracle

    Messages:
    19,044
    Likes Received:
    12,608
    Trophy Points:
    298
  8. droog

    droog Type 2 · Member

    Messages:
    10
    Likes Received:
    0
    Trophy Points:
    41
    Well... I hit a new low today. On the third day of my fast I hit BG=45 (2.5) and confirmed it a few minutes later as BG=46.

    This was around 12:30 pm. I felt fine. No problems what so ever. An hour later it was up to 55 (3.0). Three hours later it was 65 (3.6). By then I was feeling tired. Time for a siesta.
     
  9. droog

    droog Type 2 · Member

    Messages:
    10
    Likes Received:
    0
    Trophy Points:
    41
    Anyone else letting their blood sugar crater during extended fasts?
     
  10. Roggg

    Roggg Type 2 · Well-Known Member

    Messages:
    268
    Likes Received:
    158
    Trophy Points:
    103
    Mine doesn't crater. I've never been into the 3s, even on multi-day fasts. TBH I would probably be a little bit freaked out if it did.
     
  11. LaoDan

    LaoDan Type 2 · Well-Known Member

    Messages:
    927
    Likes Received:
    594
    Trophy Points:
    153
    Checking my history, lowest I’ve been is 3.6. note, I’m not using insulin.

    I usually feel ok at this range if I’m in ketosis, otherwise I feel like I’m out of gas.
     
  12. bulkbiker

    bulkbiker Type 2 · Oracle

    Messages:
    19,044
    Likes Received:
    12,608
    Trophy Points:
    298
    You still taking the metformin?
    Might be worth considering dropping it if extended fasting?
    See what happens then?
     
  13. brassyblonde900

    brassyblonde900 Type 2 · Well-Known Member

    Messages:
    331
    Likes Received:
    567
    Trophy Points:
    113
    I find that with any Abbot freestyle glucometer, my BG give ultra low readings on fasts.
    I have driven myself crazy testing with multiple glucometers.
    I now use a CGM and just watch trends which for better or worse lets me know how meals impact me.
     
  • Meet the Community

    Find support, connect with others, ask questions and share your experiences with people with diabetes, their carers and family.

    Did you know: 7 out of 10 people improve their understanding of diabetes within 6 months of being a Diabetes Forum member. Get the Diabetes Forum App and stay connected on iOS and Android

    Grab the app!
  • Tweet with us

  • Like us on Facebook