Is it that artificial light drops T levels, or is it the lack of sleep? Though admittedly the former often leads to the latter.

https://www.sciencedaily.com/releases/2011/05/110531162142.h...

In mammals generally? Sorry, couldn't resist - in truth your question is good because while "sleep" is repeated endlessly, not just in the news but often by researchers who aren't controlling for photoperiod - that's NOT what the research says. It's light that's key, controlling the master hormone melatonin. Which is also a stunningly efficient antioxidant, of supreme use in taking out the garbage - something not irrelevant to Alzheimer's. If you sleep into the light regularly,long sleeps, your lifespan actually shortens.

Pretty much impossible to separate these days.

Testosterone also drops from high consumption of animal products.

But consumption of animal products have dropped since the 70s.

Testosterone drops from high consumption of soy products too, so what are you going to do?

It actually doesn't [1] [2]. But if it did, then just avoid both.

[1] Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis.

https://www.ncbi.nlm.nih.gov/pubmed/19524224

[2] Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence.

https://www.ncbi.nlm.nih.gov/pubmed/20378106

It actually does, there is a documented event of it happening, but to be fair it is harmless for the majority of the population in resonable consumption : https://www.ncbi.nlm.nih.gov/pubmed/18558591

A 60-year-old man was referred to the endocrinology clinic for evaluation of bilateral gynecomastia of 6 months' duration. He reported erectile dysfunction and decreased libido. On further review of systems, he reported no changes in testicular size, no history of testicular trauma, no sexually transmitted diseases, no headaches, no visual changes, and no change in muscular mass or strength. Initial laboratory assessment showed estrone and estradiol concentrations to be 4-fold increased above the upper limit of the reference range. Subsequent findings from testicular ultrasonography; computed tomography of the chest, abdomen, and pelvis; and positron emission tomography were normal. Because of the normal findings from the imaging evaluation, the patient was interviewed again, and he described a daily intake of 3 quarts of soy milk. After he discontinued drinking soy milk, his breast tenderness resolved and his estradiol concentration slowly returned to normal.

Also there is a clear explanation of why so much plant products have hormonal disruptors in it, to modulate the fertility of herbivore, but it's not a story NutritionFact would tell you

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1474615/

Plants have physical and chemical mechanisms for defense from attack by animals. Phytochemical defenses that protect plants from attack by insects include antifeedants, insecticides, and insect growth regulators. Phytochemical options exist by which plants can modulate the fertility of the other major group of plant predators, vertebrate herbivores, and thereby reduce cumulative attacks by those herbivores. The success of such a defense depends upon phytochemical mimicry of vertebrate reproductive hormones. Phytoestrogens do mimic reproductive hormones and are proposed to be defensive substances produced by plants to modulate the fertility of herbivores.

So in huge quantities it rarely happens... soy is also completely optional and not necessary, so not a big concern. Avoiding animal products is laughably easy without soy.

80's myth. It's been ruled out by population studies in Asia.

I'm wondering if the downvotes are from me not citing sources or from people getting triggered.

Definitely the former. HN doesn't take well to people making unsubstantiated assertions.

If you want to make a statement like this, don't bother unless you have evidence.

It's also usually better to frame it around the evidence, like "this study from UCLA found that higher consumption of animal products led to decreased testosterone levels". This way, the discussion will be focused on the evidence or the conclusion you drew from it.

“The atom bomb works. Fission makes uranium explode.”

See how I didn’t need a citation?

It’s because the facts are not only well-understood, but a river of citation is ready to flow for you, and you would have to dig for verifiable evidence. You could pull up a youtube video, and watch facts unfold, as real world events from the past.

“My pets love me. I know this is true because I see it in them every day.”

You know what? Possible. But you couldn’t offer a citation, if you wanted to. And on top of that, there’s no easy way to discern what goes on inside an animal’s mind, or whether the situation changed and the statement no longer holds up.

“Animal products cause problems for those who consume them.”

Is a broad statement, enough to be useless.

“It’s been found that consuming animal products is associated with this specific problem.”

Better, but says who? And associated does not indicate cause and effect. It doesn’t even indicate a direct relationship.

“Consuming animal products causes this specific problem.”

How? Under what conditions? What’s the mechanism? Who can replicate these results? Why is it not universally applicable, when we can look back on history, and point to people living over 100 years, without encountering the specific problems mentioned?

Some statements might warrant citations, while some might not. That is your argument, right?

Given! Now, hop along your merry way!

Eating meat is a manly-man activity and what no one wants out of study like this is to have their preconceptions challenged or to hear they might have to change their behaviour in any way.

>> Eating meat is a manly-man activity

This is something that baffles me. The biggest, strongest mammals are herbivorous - elephant, bull, bison... Even the best carnivorous animals meditate for a few hours and seek divine help before messing with these guys.

Why is eating grass, not a manly-man activity?

> Eating meat is a manly-man activity and what no one wants out of study like this is to have their preconceptions challenged

Not really - for example most “manly-men” can agree heavy drinking decreases testosterone levels.

> Testosterone also drops from high consumption of animal products.

Does it? As far as I can tell high levels of saturated fat increases testosterone levels.

> If you take men on a high-protein diet—”meat, fish, poultry, egg white[s]”—and switch them to a high-carb diet of “bread, vegetables, fruit, and [sugary junk,]” their cortisol levels drop about a quarter within ten days. At the same time, their testosterone levels shoot up by about the same amount.

https://nutritionfacts.org/video/the-effect-of-animal-protei...

> After the intake of cow milk, serum estrone (E1) and progesterone concentrations significantly increased, and serum luteinizing hormone, follicle-stimulating hormone and testosterone significantly decreased in men

https://www.ncbi.nlm.nih.gov/pubmed/19496976

Nutritionfact is a poor science site pushing an undisclosed vegan agenda using chery picked studies.

I’m not sure what I’m meant to take from those links. Do you know of any direct studies comparing similar macros etc to isolate meat or any longer term analysis across similar target demographics?

The first one seems to be about low carb vs high carb - where was the meat + carb vs no meat + high-carb comparison?

The second seems to be specific to milk and not animal products in general.