Garmin has, accidentally I'm sure, put the tool for you to get very angry -- and healthy -- at the same time in your hands at a reasonable price.
Specifically, any of their "smartwatches" that can do overnight HRV.
It takes 2-3 weeks to get a baseline but once you have it you can do "notch testing" if you are careful and change one thing -- specifically, what you eat.
I just ran one of these.
Those who have followed my writing over time know that in 2011 I changed my food intake to be low-carb, high (animal) fat, moderate protein and it changed my life. 60lbs disappeared without effort and vigorous exercise became not difficult and even enjoyable. Its 13 years later and at 61 I still find running enjoyable along with all manner of other vigorous outdoor activity such as back-country hiking and skiing. Indeed just a couple of days ago I got back from skiing -- at 10k feet altitude in Colorado. It was awesome.
The so-called (as claimed by various medical "authorities") inexorable path of obesity and Type II diabetes halted, reversed and my insulin sensitivity returned over time. Not one drug was involved in any of that, by the way, and thus there were no drug adverse effects either (they're not "side effects" when they harm you so stop calling them that. We should all pledge that anyone using the term "side effects" instead of the proper term "adverse effects" gets an immediate baseball bat to the mouth.)
Over the last few years I've become more and more convinced that the largest issue for non-diabetic people isn't the carbs per-se, other than the stupidly-fast processed carbohydrates -- its seed oils.
I've "busted" local eateries serving them without my knowledge by, for example, cooking vegetables in them or serving me "butter" that really isn't. It is 100% repeatable -- it will tank my overnight HRV every time.
So I decided to try something as a "notch test" on fairly fast carbs in the knowing absence of seed oil of any sort.
Back from my carb-heavy days I had bought a breadmaker; a fairly nice one from Williams Sonoma. It has sat in my kitchen cabinet for more than 10 years unused. Plugged it in, it powered up. Ok.
I went to the store and bought a bag of bread flour and the smallest package (3 packets) of yeast.
Into the machine went the following:
2 cups Bread Flour
Sugar (ordinary white, granulated)
Salt
Yeast
Warm water
Melted butter (not the called-for vegetable oil)
Push button, came back in 3 hours.
There's a nicely-baked loaf of bread in there.
So I slice off two thick pieces, slather in more butter, and eat them yesterday afternoon and early evening, respectively.
What happens to my overnight HRV?
Its within the normal range.
Yes, my water balance shifted (as it does when you run on carbs) because carbs require more water to process than fats. And while I didn't look I'm sure that I'm not in nutritional ketosis at this point for that specific reason.
But..... no adverse HRV impact at all.
Now I'm not insulin resistant anymore -- I was 15 years ago, but going low-carb reversed that over time. It took several years so I would not expect this to be a good idea if you are insulin-resistant, as eating carbs like that will blow up your blood sugar levels. And were I to return to this on a regular basis the same thing would almost-certainly happen to me.
However, this is a very solid piece of evidence that the bigger impact on your health is in fact those goddamned seed oils and for me, at least, its irrefutable in that a challenge of baked goods where I know there are no seed oils in them because I put the ingredients in the machine and there were zero such in the ingredients it did not hit my overnight HRV despite being wildly carb-laden.
Folks, I said over a decade ago that seed oils are literally "heart attack in a bottle."
This was based on the fact that all substances, concentrated sufficiently, are poisonous and it is up to someone to demonstrate that a specific dose is safe, not the other way around and the correlation with increasing obesity, heart disease and diabetes tracks almost-exactly with the increase in seed oil consumption on a per-capita basis. On the other side of the debate to counter this correlation there is no such evidence of safety when it comes to seed oils and in fact we now know that the so-called "consensus" was tainted at best and quite-possibly deliberately corrupted.
Subsequent reexaminations of this evidence by nutrition experts have now been published in >20 review papers, which have largely concluded that saturated fats have no effect on cardiovascular disease, cardiovascular mortality or total mortality.
Ancel Keys alleged "work" was false; whether it was deliberately false originally doesn't matter. The fact is that the claims were not reproduceable and yet it turned into the basis of a very profitable set of conditions for both the food and medical industries, all of which have made a crap-ton of money off cheaper food ingredients on the food side and human misery, disease and death at insane profits for every single entity involved on the medical and pharmaceutical side. You're free to conclude this was a "mistake" -- I argue it was deliberate and worthy of capital punishment of every single person involved both originally (although they're likely already dead) AND ALL WHO ADVANCE IT NOW THAT WE KNOW IT WAS AND IS BOTH BULLSHIT AND IS ACTIVELY KILLING PEOPLE.
But you don't have to take my word for it or read studies because you can test it in your own physiology, which is of course distinct to some degree from everyone else's and is also 100% true 100% of the time for any person who does so and is thus irrefutable for you as an individual.
Now, of course, we have also polluted this debate with so-called "climate science" arguing that animals are polluters. That's so fucking laughable that anyone arguing it should be executed where they stand; this nation, for example, has been estimated to have had thirty million bison roaming the United States just prior to Columbus' arrival. Obviously they did not make the planet hot enough to kill everyone and in fact by 1890 there were only a thousand left and we did not fall into an ice age as a consequence of that slaughter.
It ought to be screamingly obvious that animals are in fact part of the ordinary cycle of the Earth's biome and that is a good thing. After all we're animals too, you know, and we fart just like a cow or bison does.
All of this crap has combined over time to lead so-called "experts" recommend that you quite-literally slowly poison yourself and worse, your children. Go look in any store and see what's on the label of every infant formula, typically as the third ingredient by volume. Yep -- seed oils, all of which hit my HRV severely and that directly implicates metabolic damage.
This crap is an utterly huge component of the medical mess. I'm convinced of it. While I'm sure there are people who don't have the negative metabolic impact of what I witness myself I also believe its extremely rare because every person I've talked with that has such a device, and who I've convinced to remove these substances even for a single day sees improvement and thus sees the damage for themselves on a notch challenge. I've yet to run into the person without that response - again, I'm sure such people exist but its very uncommon and this sort of evidence is something you can develop and test for yourself, personally, with a tiny bit of effort.
If you do, and find the same thing, then please explain why you let the government, doctors, so-called "health authorities" in the media and elsewhere make a recommendation that you kill yourself by eating metabolic poisons rather than the alternative (animal fats) that have no such impact on your body without doing anything to those who, on the evidence in your person with your own individual testing, have been and are trying to poison you -- and your kids.
Do you really hate yourself and your children enough to let this go unanswered when the clear motivation is simply MONEY at the expense of your health and life?
And oh yes, they all know it too -- the data has been there for decades and deliberately ignored.