from Hacker News

Fasting lowers blood pressure by reshaping the gut microbiota

by porterde on 7/17/21, 4:50 PM with 115 comments

  • by inglor_cz on 7/17/21, 7:10 PM

    N == 1 here.

    I had a huge drop in blood pressure once I started fasting daily. Even though I lost only a modest amount of weight (approx. 10 pounds; I was never obese, only slightly overweight with BMI cca 27), my blood pressure plummetted from 150/95 with medication to some 115/75 without medication within a month.

    This holds even when I no longer fast daily, only a few times a week. Additional Concor, taken against post-Covid arrhythmias, reduced my BP to some 105/70 when relaxed. Going any lower would actually mean a risk of fainting.

    This seems to be consistent with the theory of gut microbiota being reshaped. I can also tolerate milk slightly better than before; my tolerance still has limits, but I won't get a rash after a single cappuccino, which I most definitely used to before.

  • by vericiab on 7/17/21, 9:12 PM

    I don't tend to experience hunger and, as a result, interrupting my activities to eat multiple times per day can feel like a bit of an inconvenience. So I've frequently fasted daily since before "intermittent fasting" entered the common lexicon. It's not really intentional though, I will quite literally forget to eat or otherwise just don't make it a priority.

    In my experience, I'm not sure it's quite the panacea it's sometimes made out to be. Perhaps there are psychological benefits to intentionally fasting that I'm missing out on. In any case, quite often when I'm wondering why I feel like shit I end up realizing something like I haven't eaten in 24 hours or in the last 48 hours I've eaten less than 1000 calories. Oops. I'm trying to be better about regularly eating 2 meals per day because I really do feel better if I've been eating consistently.

    I'm not sure it's doing my blood pressure any favors either. Despite regular fasting and having a BMI of 18.1 (technically slightly underweight, as the lower bound of a "healthy" BMI is 18.5), my blood pressure is usually around 140/95. But who knows, maybe it would be higher without the fasting.

  • by foobiekr on 7/17/21, 6:51 PM

    The gut biome must be at least strongly influenced by the environment you create - change should be assumed as soon as you change that environment.

    But does the change mean anything?

    I think this is going to turn out to be an incomprehensible problem that we will never really get a handle on due to the time it would take to even begin to understand things. We just aren’t able to run those experiments and this is the general domain where science for us fails and degenerates to just-so stories and observational correlations “studies.”

    To illustrate…

    Last year I did 5 months of OMAD to lose weight. I’d gained a bunch in the first few months of lockdown. It wasn’t hard but it wasn’t easy especially because my wife, who is effortlessly slender and eats a ton, needs to eat a big breakfast every day.

    I often wonder if a gut biome transplant from her would give me that - I’d love to see someone actually do that experiment.

    But not on me.

    Her and her brother can literally eat bags of iced mothers cookies per week and stay slender - her GP says she needs to gain weight. It just isn’t going to happen. It took me awhile to understand what’s going on but my observation is they get really warm and fidgety for the hours after overeating and just burn it off sitting there. Her whole family is pretty lazy, they don’t exercise recreationally. They aren’t running it off or whatever.

    Whereas my chronically overweight family lives ends up with moderately high boood pressure, they also all live long lives mostly free of debilitating illness until the end. Her family, on the other hand, has all manner of terrible issues once they hit their 70s…

    Obviously this could just be “genetics” but whose? Their nuclear genetics or their inhabitants? And do the long terms come out of that?

    I honestly don’t think we will ever know without experiments. And given things like the above I wonder if they can be even done, even if you decided to ignore the potential long term…

  • by omosubi on 7/17/21, 6:06 PM

    I just did a 40 hour fast to see if i could do it and it was a lot easier than i thought it would be. I'm trying to build up to a week long. We'll see how it goes.

    It's a shame that fasting has been eliminated from the culture, but i guess that's what happens to things you can't make money on.

  • by zkirill on 7/17/21, 9:35 PM

    Fasting was one of the most memorable and shaping experiences of my life. I fasted for three days (72 hours of nothing but water) and observed so many interesting and fascinating things happening to my body each day: skin flare ups and subsequent clearings, changes in mouth and gut odour, periods of brain fog and brain clarity, cravings followed by complete loss of feeling of hunger. Every passing day had different effects. The most memorable was an astronomical improvement in my olefactory senses. By day two I was able to pick out the smell of individual ingredients in any dish being prepared in my vicinity. By day three, I lost the majority of my muscle mass.

    The one and only time I ever did this was when I was young and in extremely good health (daily intense exercise, excellent diet, no health conditions). Slightly worried about doing it again today. Also, quite concerned having since learned that brain mass is the first stored energy source your body will go after during what is effectively starvation. Perhaps someone more knowledge on here can comment on how true that is.

  • by malux85 on 7/17/21, 6:07 PM

    I have been intermittant fasting for a month now and the results are fantastic. The mental clarity alone is worth it, let alone the weight loss and general well being (better sleep, better digestion)

    I only eat for 4 hours a day, some days 1 meal and grazing, other days 2 meals, but nothing outside those hours except water and tea (with no milk)

    I feel fantastic, I'm never going back to any other food schedule.

    The downside was that the first week was incredibly hard, I felt dizzy and had spells of intense anger, but I distanced myself from those I love so as not to accidentally explode at them and just got through it, now after nearly a month, it feels normal and I just feel great. Highly recommend it.

  • by qwertox on 7/17/21, 6:23 PM

    When I do sports (riding bike every day for at least one hour in mostly anaerobic mode) after not eating for at least 18 hours or so (which I don't do often), I feel like I've got unlimited resources of energy available.
  • by shoto_io on 7/17/21, 6:41 PM

    I regularly do IF and have seen great results for my weight and blood pressure.

    Just a word of caution about this study: it’s still only an animal model (rats). Should be added to the title for clarity.

  • by walshemj on 7/17/21, 6:31 PM

    Interesting after I had been on antibiotics continuously for an extended period - the corelectoral surgeon prescribed a course of symprove probiotic.

    Which does seem to make me feel a lot beter il have to experiment with fasting as well.

  • by mavci on 7/17/21, 6:35 PM

    Did you know that fasting for one month a year is obligatory in Islam?

    “O you who have believed, decreed upon you is fasting as it was decreed upon those before you that you may become righteous.

    Fast a prescribed number of days. But whoever of you is ill or on a journey, then let them fast an equal number of days after Ramaḍân. For those who can only fast with extreme difficulty, compensation can be made by feeding a needy person for every day not fasted. But whoever volunteers to give more, it is better for them. And to fast is better for you, if only you knew.“ - Surah Al-Baqarah 183-184

  • by frereubu on 7/17/21, 7:44 PM

    This study is in rats, and if I'm reading the article correctly it also involves a population of rats that are bred to be predisposed to hypertension. So although it sounds like there are some interesting anecdata stories in the comments, this is very far from being generalisable to human populations. Seems like it would be a pretty easy study to do in humans though, to the point where I wonder if it hasn't been done already, even if not specifically focused on gut bacteria.
  • by rozab on 7/17/21, 7:19 PM

    Does anyone have any fasting advice from a reputable health authority?

    For some reason the NHS doesn't really have any online, even though a sizeable proportion of the population observe Ramadan. They usually have good, well-cited articles on this kind of thing.

  • by snthd on 7/17/21, 7:09 PM