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AHI and diet - tmoody - 08-19-2019

Hello again. It's been a while since I've posted. My basic info is: 66 year-old moderately obese male (BMI=33), idiopathic complex sleep apnea, using Philips System 1 ASV for a few years now. General health is good. No medications.

I was diagnosed with OSA in 2006 and used a non-data-capable Resmed S8 for almost 11 years, at a constant pressure setting of 11. When that machine finally broke down, I was given a bi-level "DreamStation" a few years ago. That machine revealed a fair amount of PB and CA events. After another sleep study, which failed to reveal any underlying cardiac condition, switching to a neuro sleep doctor, instead of a pulmonologist, the ASV was prescribed. With the help of the good people here, and a lot of patient self-experimentation, I got my settings dialed in. Since then, my usual AHI is under 2. Occasionally I'll get a few days of higher readings; but I'll also get strings of readings below 1. 99.9% of all events recorded are hypos. Once in a while a CA will sneak in; very rarely, an OA. And that's been fine. My more pressing sleep problem has been the normal senior's problem of waking up earlier than I'd like to.

Two weeks ago, I started getting higher AHI readings: from 5s to 9s. Again, they've been almost all hypos, with a few CAs and a single OA in the mix. My two-week average for this period is 6.1; I had just one day under 5, with a 3.0. I feel generally okay through all this, except when it gets up to above 7, at which point I feel jetlagged during the day. But of course I've been concerned, and would like to know what's going on.

I haven't fiddled with settings; I figured I'd just wait it out and see if it went back to normal. Then I noticed something interesting. I tried to discern any change in my daily living habits that might account for the high AHI. I couldn't find anything, until I checked my diet diary. I eat a healthy whole food plant-based diet, but I'm still obese, because I just eat too much. No mystery there. Two weeks ago, I started a strict kind of regimen that involves three measured meals and absolutely no snacks. So I eat dinner at 6:00 pm and then nothing until the following morning at about 7:30  -- almost 14 hours of fasting.

The first night of that diet was the first night of higher AHI, I discovered.

As I mentioned, there was one day with a lower AHI of 3.0. On that day, I had eaten a starchy snack in the evening: some rice and grilled peppers. I didn't do that again, and the numbers went back up.

My birthday was this past weekend, and we had a little party yesterday. I decided to use the occasion to do a little experiment. I simply ignored the diet, ate whatever I wanted, had a couple of beers, and enjoyed myself. In the evening, I had a leftover slice of key lime pie (my preferred birthday cake). This morning my AHI was 1.6.

This is not much of a data set to form any strong conclusions, but I'll add this. When I was younger, I could do fasting pretty easily, bus as an older person I've discovered I don't tolerate it well. If I try to fast for a day, by late in that day I start to feel definite "fight or flight" sensations of sympathetic nervous system arousal. This current diet has been effective, in that I've dropped over 7 pounds in the two weeks, but the calories are pretty low for a man my size. And of course there's the fact that I'm fasting 13-14 hours overnight every day.

So I'm just putting this out there for your consideration. My theory is that my diet is causing my cortisol levels to go way up, and that is somehow causing the hypos. I haven't found a lot of information about the relation between cortisol and CAs or OAs, except a few studies suggesting that apnea evens cause elevated cortisol, which certainly makes sense. But since idiopathic CA is still very...idiopathic, I'm not ruling out the possibility that there's a two-way causal connection.

Anyway, my plan is to modify my diet to include an evening snack of oatmeal and blueberries, and see what happens to my readings. Maybe this experiment will be of use to someone else who reads this.

Have a great day everyone.


RE: AHI and diet - Gideon - 08-19-2019

Are you by any chance diabetic (prediabetic counts)?  The change in diet could be causing your blood sugar to go low (especially when my carbs are way down) and I find that does bump my AHI up a bit, not alarmingly so, but a bit.


RE: AHI and diet - tmoody - 08-19-2019

(08-19-2019, 10:45 AM)bonjour Wrote: Are you by any chance diabetic (prediabetic counts)?  The change in diet could be causing your blood sugar to go low (especially when my carbs are way down) and I find that does bump my AHI up a bit, not alarmingly so, but a bit.

Good question. Before I switched to plant-based diet I was considered pre-diabetic, since my fasting BG was 103. After switching, FBG went down to 93, which is considered "normal" by the medical community, but still on the high side, really. And that was over two years ago. I haven't had it checked since, so it's possible it went back up. A lot of people lose weight when they switch to a vegan diet. I did too, but the weight came back, so it's possible that my FBG rebounded.

But we're on the same page with this line of thinking. When BG goes too low, the way the body signals for more to be released is to produce cortisol. And now that you mention it, I've experienced a few episodes of obvious hypoglycemia since starting my recent weight-loss phase: woozy lightheaded feeling.

If my evening snack experiment works, we'll have a better picture of what's going on. And if my weight loss continues, I should expect better glucose control anyway. I get a reasonable amount of exercise, but obesity will always make problems.


RE: AHI and diet - Justbreath - 08-19-2019

Very interesting, I have noticed when I eat late at night my ahi goes up significantly. Not sure why


RE: AHI and diet - Gideon - 08-19-2019

One of my quirks is that I believe that your either have diabetes, and prediabetes does NOT mean that you don't have it.
I equate Prediabetes to stage 1 cancer.  Managed Type 1 diabetes would be Stage 3 cancer.  (obviously not as bleak of an outcome).  Prediabetes means that you have diabetes, but it may be fairly easily managed or controlled frequently with diet and exercise.  OK, I'm jumping down off the soapbox for now.


RE: AHI and diet - SarcasticDave94 - 08-19-2019

I realize this isn’t exactly the diet aspect you’ve mentioned tmoody, but that bariatric sleeve I had done 3 years ago plus just eating less accounts for my 110 pound weight loss. That cut AHI roughly in half, but it was still very high.

I’m not diabetic (pre equals diabetic) or otherwise, but I’ve noticed mom’s health issues in general fluctuate in relation to her sugar levels and she’s diabetic.


RE: AHI and diet - tmoody - 08-19-2019

(08-19-2019, 03:46 PM)bonjour Wrote: One of my quirks is that I believe that your either have diabetes, and prediabetes does NOT mean that you don't have it.
I equate Prediabetes to stage 1 cancer.  Managed Type 1 diabetes would be Stage 3 cancer.  (obviously not as bleak of an outcome).  Prediabetes means that you have diabetes, but it may be fairly easily managed or controlled frequently with diet and exercise.  OK, I'm jumping down off the soapbox for now.

I don't dispute that. These terms have no real meaning. The numbers indicate the degree of loss of glycemic control, if any. A person with FBG in the 90s does not have good control. The pancreas stops putting out insulin over and above it's normal pulse when BG gets to 84, so that's clearly what the pancreas "thinks" is normal.


RE: AHI and diet - tmoody - 08-22-2019

Well, it's a few days later, and I've experimented with (a) having a substantial snack in the evening, at 9 pm or so, and (b) just getting my daily caloric intake up higher, but not so high that I stop losing weight. Both have resulted in AHI back below 3. Of course, it's too soon to draw any grand conclusions, but it seems to confirm the hypothesis that I was simply eating too little, and the resultant stress was somehow triggering hypos.

On my last visit to the sleep doc, in January, he noted that over 99.5% of my breaths were initiated by me, not the ASV machine, but on "bad" days that percentage would drop, with a pretty tight correlation to the actual hypo events, as you'd expect. The question of what causes the intervals of weak breathing remains unanswered, but I have at least a working hypothesis that the stress hormone cortisol is playing a role.

I was just doing an Internet search on the relation between cortisol and alcohol, since as I mentioned in my first post I also had a couple of drinks on my birthday last weekend, and had a low AHI the next morning. I said in that post that I had a couple of beers, but in fact I had two glasses of white wine. I had forgotten about this, since I rarely drink white wine. To my surprise, I found this article, https://www.abc.net.au/science/articles/2009/08/25/2662698.htm according to which different drinks have different effects on cortisol. Beer, my usual preference, reduces it at first, then increases it. White wine, but not red, decreases cortisol without rebound. I have no plan to start drinking white wine regularly, but I thought this was interesting. [url=https://www.abc.net.au/science/articles/2009/08/25/2662698.htm][/url]


RE: AHI and diet - SarcasticDave94 - 08-22-2019

Glad your AHI is trending back to good. Best to ya


RE: AHI and diet - tmoody - 08-23-2019

A quick update: My experiment hit the wall last night. Although my food intake should have been ample, my AHI was 10.5, almost all hypos, with three CA events. I'd upload the Oscar image, but I'm having trouble with that, and indeed with Oscar itself missing data.

If the AHI graph is to be trusted -- and I'm far from sure that it is -- a big part of the AHI was a large surge that occurred after I disconnected to go to the bathroom. But there's probably missing data, so I don't really know.

I haven't changed settings in over a year, as they've been working pretty well for me, although I will say that my AHI in 2019 has been a bit higher than in 2018, but not alarmingly so. It's only in the past couple of weeks that my 2-week average has been higher than 5. As I described earlier in the thread, I correlated that with starting a weight loss diet. That may still be right, but I'm at a loss to explain last night.

You'd think I'd be feeling pretty ragged today, but I'm not.

In case anyone's interested, the settings are:


Machine Settings

PAP Mode ASV (Variable EPAP)
Min EPAP 8.50 cmH2O
Max EPAP 22.00 cmH2O
Min IPAP 8.50 cmH2O
Max IPAP 25.00 cmH2O
PS Min 0.00 cmH2O
PS Max 16.00 cmH2O
Flex Level x2
Flex Mode

Heated Tubing
Yes
Humid. Lvl.
x3
Humidifier Status
Disconnected
Ramp Pressure
4.00 cmH2O
Ramp Time
5.00 Minutes