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Before the reactions to the headline get too out of hand, the article says the study couldn’t rule out that obesity and diabetes might drive this change. Occam’s Razor leads me to lean on this more than any other exotic explanation.

Of course, PFAS and microplastics aren’t great for sperm health, but neither were leaded gasoline and DDT before they were curtailed.

Also, it's highly person dependent.

I'm an obese american (lost 10% of my body weight in the last 7 months, so almost not obese anymore) who is 30+, but my testosterone has measured between 850 and 1400 in the last 7 months.

That probably helped with my weight loss, but I have a full head of hair still and am somewhat likely to keep it.

We'll likely spend longer measuring what the hormonal effects of PFAs and microplastics are than we'll have pfas and microplastics to deal with.

Good point. Age and obesity are the strongest correlates with low testosterone. Increases in sedentary lifestyles probably aren't helpful either, but not clear if that is anything other than a proxy for obesity
I’m pretty sure other experts are also saying that it’s due to a different way of measuring levels.
Which means, given GLP-1s, we should see a reversal in the next few years.

Random aside: is there a correlation between GLP-1 and vaccine acceptance? As in, given enough time, would one expect to see an obese, diseased, low-T population concentrating in on itself?

> Obesity was also not controlled for, which is known to be strongly correlated with low testosterone.
Testosterone is directly causally inverse to bodyfat in men (once above some very low baseline)

Fat directly converts testosterone to Estrogen via a process called aromatization.

Personally my Testosterone close to doubled when going from 25% bodyfat to 13%. I get blood tests regularly and can see the levels fluctuate pretty closely with fat levels

In the past decade, research suggests that testosterone levels have actually gone up[1].

[1]https://www.cremieux.xyz/p/why-are-testosterone-levels-risin...

Really makes the study completely pointless when the last 50 years has also seen the rise of the global obesity epidemic.
I don’t understand why obesity seemingly gets tossed aside when this subject comes up.

It’s the one problem you can see in plain sight at any gathering of people.

That's literally the main point of the article, the stand-first: "Exclusive: Researchers warn of ‘major crisis in male reproductive health’ partly driven by obesity and diabetes"
Because especially in this forum, obesity literally does not exist and if it does is never the person's fault but rather big food producing addictive meals / not walkable cities / exercise is bad for your joints / et cetera ...
Because it's too obvious. There needs to be some hidden, world encompassing conspiracy, so that people feel superior when they are one of the few enlightened ones that see through the matrix and start drinking raw milk to live like our testosterone pumped ancestors.
“The solution that’s being promoted is that we give you testosterone,” he said. “But if you give a man testosterone, you switch off his sperm production. I’ve seen that in the clinic.”

Interesting…

As explained by https://www.nytimes.com/2026/05/12/magazine/testosterone-mas..., "Supplementing with testosterone sends the message to the brain that testosterone is in oversupply, shutting down the testicles’ production of testosterone and sperm... The hormone is so incredibly effective at decreasing sperm counts that it is being tested as a possible male contraceptive."
It's becoming clear that it's not permanent. Discontinuing exogenous testosterone will lead to restarting your own body's production - it just takes a bit, and isn't fun to deal with.
Are you being sarcastic? That has been widely known by steroid users for decades, that's why many of them supplements with hCG in an attempt to preserve their natural production.
I really wonder, what is “normal”?

One class of doctors thinks roughly 250 is enough for a middle aged guy - anything over shouldn’t be medically treated. Of course, the “men’s clinics” don’t rest until it’s over 1000...

With the standard range so wide (even after age adjustment), why isn’t it measured annually, like the CBC and others?

Sure, it’s easy to point at obesity, but statistical ranges completely fail the individual.

There are wide ranges but it's more about how you feel personally and what you've noticed over time. Some men have below average T but feel great and build serious muscle anyway.

The two sigma range is something like 300-900 with std being 150 and median 600. This is for what is labeled as healthy 18-39 men. It doesn't include obese men.

If you want to take something away from it, just get yourself measured a few times over a few years. Then later if you have issues that relate to low T or whatever you can flag it with your doctor. In my case, it was super important because I found out I am in the top 0.01% of (healthy) total T producers. If I had "low T" type symptoms and went to my doctor without that information - they'd be like, "no, your T is amazing actually."

Everyone has a different baseline. I only wish I started measuring before I was in my mid-30s because I feel my levels before were even more ridiculous.

The effect is so variable that the reference range is nigh meaningless. Some people feel great at 300ng/dL. Some people experience genuine low-T symptoms at 650 that are fixed by bumping it to 1000. Some people are naturally over 1000 and have otherwise average hormonal profile (hair growth, muscle growth).

Also, the reference range is defined by an age span that is too wide to be useful, something like 21-59. The reference range is completely meaningless for a 25 year old man. Also the level varies drastically throughout days and weeks, so that one test is not a useful indicator of anything unless it's off the charts.

Basically, if you have low-T symptoms you should probably just get on T regardless of what number the test says. Find a doctor who agrees.

I'm old, but I get this subjective read: of my friends and even family who had sons, they seemed smaller and less bold than we were 50 years ago.
This study is measuring adult men’s testosterone levels, not children’s. Boys don’t even produce that much testosterone until puberty.

This study has more to say in comparing adult men today to their grandfathers.

There is also correlation of the elimination of Lead Paint to violent crime. So that may need to be taken into account.

Lead Paint elimination started in the Early 70s IIRC, so the same time period :)

less bold? what do you mean?
High cortisol lowers testosterone - some adaptogens like ashwagandha modulate the HPA axis and lower cortisol release, increasing T levels
I wonder how this correlates to Prostate Cancer. From what I heard, high testosterone can be one of the causes of Prostate Cancer. But that is over a long time.

So if levels are falling, is prostate cancer lowering a little bit ? But that will be hard to determine due to the advancement of Medical Treatment over the past 50 years.

> Rising levels of obesity and diabetes

Plastic Bottles also replaced glass starting in the early 70s too. I remember reading some type of plastic can leak estrogen into the food. So seems a lot of things happened of the past 50/60 years that will impact ones health negatively.

Could this be a possible factor in the reduction in violent crime (at least in some countries)?
That is extremely closely linked to lead, especially the ban on leaded gasoline
Also, aging populations.

There's a larger proportion of older males in the population now than there has been in most of history. Testosterone decreases as we age. The average is across _all_ males, even those outside of reproductive years. I assume if we controlled for outliers, that the results would be fairly comparable across time.

Per the article, they did at least try to control for age (it'd be a completely uninteresting result if they hadn't). The big concern is that they did _not_ control for obesity or diabetes.
“Obesity and diabetes could easily account for all of this,”

Wither Ozempic? I've seen several friends and family members use it to great effect and thought it might sweep the nation. But I imagine most of the same barriers that keep people from eating better or moving more are also in play when trying to engage with any new habit.

soy, cortisol, plastics, birth control remnants in the water and food supply, adipose tissue accelerating conversion of testosterone into estradiol, and compounds acting to keep free testosterone levels low and bound testosterone levels high. combine that with sedentary lifestyle, the demonization of red meat healthy fats and cholesterols (cholesterol is extremely close to testosterone and converts easily) and the systematic promotion of a plant based heavily processed diet can easily lead to this. the traditional diets of slaves and serfs was low meat & high grain to keep them weaker dumber and shorter in general. the lowered testosterone and will to fight and resist oppression was also a "feature, not a bug" as my llm likes to say every chance it gets.

the industrial revolution has been a disaster for the human race.

I'm playing with fire going against the narrative, but I'll just say this:

You should be highly skeptical of any claims of drastic variance in human biology over short time periods.

Sperm counts, too, have dropped precipitously.
Seems like a minor issue, since most men only utilize their sperm two or three times in their entire lives, if at all. Maybe men should be freezing sperm while they're young and virile.
I think testosterone increases when men do strength training.

I wonder if men nowadays don't move around or lift things as much.

America found the solution, put everyone on enhanced TRT and cash a shit load of bucks in the process :)

Others are trying to regulate pesticide, junk food (obesity, diabete). For instance nutriscore in Europe, also the recent change on pesticide allowed.

I'm not sure it will be enough, but at least they are attacking to the root cause. You're not just adding even more problem, like the increased cardiovascular event or erectile dysfunction with overdosed TRT.

Same for the semaglutides that everyone and their mother take in the usa, people wouldn't need them so much if they didn't eat absolute crap all the time.

We know that semaglutides have also side effects, and that rebound happen when you stop, but I guess it's better than just fixing the food lobby ?

Lift weights. Nobody lifts weights or does labor like they used to.

Endocrine function can still be normal despite obesity. There are plenty of fat guys with solid testosterone levels because they work with their hands all day.

I'm not saying that's all there is to health, far from it, but what kind of bubble does one have to live in to not see this counterexample? Do we just casually ignore them because they fit undesirable stereotypes of "toxic masculinity" or what? You don't have to become that guy just to lift weights.

I'd say "quality not quantity" but not in this case...
Nothing a war couldn't solve
It's just our shitty food system and sedentary lifestyle but everyone is projecting their weird hangups on it
The brain of Theguardian "journalists" has also halved in the last 13 years, post Snowden, so it must be something going on. Glyphosate effects maybe ? /s
Half way to utopia.
Endocrine disrupting compounds.