I would assume most men really care about 
testosterone and fertility. This short on   testosterone has become pretty popular. It's a 
clip from this interview with Andrew Huberman   on the "Mark Bell's Power Project Podcast." 
[Andrew] "If you're not getting enough fat,   forget having decent testosterone. If you went 
on a low-fat diet, sub caloric low-fat diet,   is, you know, it's a form of nutritional 
castration, basically. Some people require more   fat than others, but that is absolutely deadly to 
the reproductive system. If you increase your fat,   in particular saturated fats…the vegan community 
is pretty angry with me right now because I said,   sin of all sins, I said that I eat butter.

I like 
grass-fed butter not I don't eat chunks of it,   I eat a little bit of it. And there's a video on 
the internet saying, you know, he's bad advice.   My blood lipids are great, thank you. Dietary 
cholesterol is, is vital for hormone production.   Some amount of saturated fat is good. If you put 
your saturated fat to zero, your testosterone will   drop. There's no question about it." I assume he's 
exaggerating there, but just in case he's not,   who eats a zero saturated fat diet? Even a 2,000 
calorie diet of just bananas has some amount of   saturated fat, like, 2.5 grams.

Everybody eats 
some amount of saturated fat, even people on a   low-fat diet, even vegans. Vegans can eat a lot 
of saturated fat, if they want to. But really,   he has two claims here. So first, he's saying 
that low-fat diets are bad for testosterone,   they are nutritional castration. [Andrew] 
"If you went on a low-fat diet, it's a form   of nutritional castration, basically." That's 
a fantastic phrase. And then the second claim,   saturated fat is good for reproductive health 
good, for testosterone levels. [Andrew] "Some   amount of saturated fat is good. If you put your 
saturated fat to zero, your testosterone will   drop. Let's start with saturated fat. Is there 
any evidence on saturated fat and testosterone?   There is, and at first glance, it seems to support 
Andrew's claim. This study found that both total   and bound testosterone levels were higher for 
those eating a high fat diet, with almost four   times more saturated fat than the low-fat group. 
This one, very similar, with the high fat group   eating more than double the amount of saturated 

One of my favorite sources for nutrition and   supplement information is They're 
about as unbiased as you can get. No ads,   no sponsorships. They don't sell supplements. 
Highly recommend them. Anyway, as they point out   about these studies, the differences found 
are small, 10-15%. And more importantly,   the low-fat groups, their testosterone levels 
are still within the normal range. And the   biologically-active, the free testosterone, the 
testosterone that your body can actually use,   was the same between groups. Probably why examine 
makes no mention of saturated fat on their page   about boosting testosterone. So it really does not 
make sense to eat saturated fat for testosterone,   but if for some reason you think you need it, 
you don't have to harm animals to get it. The   only things he mentioned, of course, is, like, 
butter and beef and egg. [Andrew] "For me, butter,   red meat from good sources, is wonderful. Eggs are 
really good." Coconuts exist and they are full of   saturated fat. So now on to Andrew's second claim, 
that low fat is bad for reproductive health,   for testosterone. [Andrew] "…absolutely deadly 
to the reproductive system." It's important to   note that the studies about saturated fat that 
I mentioned earlier, they weren't really on   saturated fat and testosterone.

They were on total 
fat intake and testosterone. So not only were the   low-fat groups eating low saturated fat, they 
were eating low fat in general, very low fat,   less than 15 percent in this study. On a 2,000 
calorie diet, that's only 33 grams of fat. And   luckily for us, there is a recent meta-analysis on 
this exact topic. They analyzed 6 studies total,   206 participants total, with low-fat intakes 
from 6.8% to 25%. 6.8? What is that, like,   2 grams of fat? 15 grams on a 2,000 calorie diet. 
To give you some idea of what that looks like,   one avocado has 21 grams. So yeah, kill me. They 
did find a positive correlation between fat and   testosterone, the low-fat groups had lower 

But there were several limitations:   lack of randomized controlled trials, only 6 
studies, small sample size again 206 participants   total. As per usual, more research is needed. 
You really cannot draw firm conclusions from   this review. So to be so confident that a low-fat 
diet is absolutely deadly to testosterone levels?   Why? What about vegans, specifically? You 
might have heard of this recent study that   found normal testosterone levels for plant-based 
eaters, whether they ate a healthy plant-based   diet or an unhealthy one. Another recent one had 
similar results no difference between vegans and   omnivores. There could be a couple reasons for 

First, again, fat intake. If we look at   that second study, we can see that while the vegan 
men were eating significantly less saturated fat,   as we would expect, overall fat intake was almost 
30 percent of total calories, or about 64 grams of   fat per day. So they were not eating a low-fat 
diet, they were not following recommendations   from organizations like PCRM that promote 20 
to 30 grams of fat per day.

[Neal Barnard] "In   the course of a day, about 20 or 30 grams of 
fat, if you're reading labels or whatever,   that's all you're going to need. You don't need 
more than that." They were eating more than double   the high end. Second, BMI. Multiple studies have 
found a negative correlation between obesity and   testosterone, and when people lose weight, 
their testosterone levels rise quickly.Even   a small reduction, a 5% reduction in weight, can 
significantly increase testosterone levels. As we   know, and as the second study shows quite clearly, 
vegans tend to have healthy BMIs. Whatever the   reason, the evidence clearly does not support 
this claim that saturated fat is needed for   healthy testosterone levels, and that vegans are 
therefore at risk for low testosterone. Even the   link between total fat intake and testosterone 
is pretty weak. That's not to say fat is not   important. You guys know me, I eat a whole lot of 
fat. And if I were a man, I definitely would not   take PCRM's advice and eat 20 to 30 grams of fat 
per day." [Neal] "About 20 or 30 grams of fat,   you don't need more than that." That was Dr. 
Neil Barnard, he's president of PCRM.

He even   says that we really only need 3% of total 
calories coming from fat. That would be 6.6   grams on a 2,000 calorie diet." [Neal] "Maybe 
only maybe about 3% of your calories every day   should come from those fats. That's it." Which, it 
might be true. I have no doubt that many people,   if not most people, could survive on a very low 
fat diet for a long time. But I don't think most   of us are interested in just surviving, right, 
on the bare minimum.

Higher fat is correlated   with benefits that maybe don't impact longevity, 
but that we really care about. I would assume most   men really care about testosterone and fertility. 
So going by the minimal evidence we have on fat   intake and testosterone, and the good amount of 
evidence we have on fat intake and heart disease,   it just does not make sense for men to eat 
a low-fat diet, vegan or otherwise.

Eating a   decent amount of unsaturated fat, it may help men 
achieve and maintain healthy testosterone levels.   And if it doesn't? These foods are still healthy 
and delicious. It's a win-win. Just for fun,   let's look at fertility, in general. For both men 
and women, saturated fat is linked over and over   and over again to worse fertility. Now, does that 
mean saturated fat is bad for fertility? No, it's   a correlation. Nutrition research is rife with 
confounders that are really hard to control for.   The average person eating lots of saturated fat is 
also eating lots of refined carbs, minimal fruits   and vegetables, is sedentary, is overweight. 
All of these are linked to decreased fertility.   Perhaps someone eating lots of saturated fat, but 
also eating lots of fruits and vegetables, is fit,   is active,.

Maybe they wouldn't have an increased 
risk for fertility problems? It's possible. But   the evidence definitely doesn't say saturated fat 
is good for fertility. What about veganism and   fertility? There really isn't a lot of research 
on veganism, specifically. There are a couple   of sperm quality and motility studies. One found 
vegans had worse motility. The other found vegans   had better motility and better quality overall, 
so not super helpful.

And also, the total number   of vegans, both studies, only 15. So yeah, I don't 
think there's a lot we can learn from this, other   than vegans can have healthy sperm or unhealthy 
sperm. Shocking! But things that vegans tend to   do, again, maintain a healthy weight, eat fruits 
and vegetables, limit mercury, right, we don't eat   fish, seem too positively influence fertility 
in various ways. And the evidence definitely   doesn't say veganism is bad for fertility. Back 
to testosterone. What if you're vegan and you   have low testosterone levels, or you're just 
worried about your testosterone levels? Well,   besides saturated fat, Andrew also recommends 
a couple herbal supplements. [Andrew] "Now,   for people that aren't getting prescribed 
trt, but want the increase in testosterone,   they're these plant compounds like Tonga Ali 
and another one, which is very interesting,   it's a Nigerian shrub called fadogia agrestis." 
Unsurprisingly, there's very little evidence for   these, either.

But there are a few things you 
can do. They're things that you really should   be doing anyway. They're important for everyone, 
beyond testosterone. Adequate sleep and physical   activity, particularly resistance training. 
Maintaining a healthy weight,. Adequate nutrition,   particularly zinc vitamin D and magnesium. It's 
hard not to get enough magnesium on a vegan diet,   but you can definitely be lacking in vitamin D and 
zinc. So make sure you have a source for those,   make sure you are eating legumes and other 
foods, pumpkin seeds, that are high in zinc.   And make sure you're taking a vitamin D supplement 
or getting some amount of sun. And of course, talk   to your doctor. Who is Andrew Huberman? I wanted 
to put this at the end instead of starting the   whole video with "this guy's a quack." I wanted 
to just look at his claims on their own and see if   they hold up, right. But it is interesting. He's a 
neuroscientist. He has actually done his research,   I mean, literally he's done his research.

makes this whole interview, and other interviews   he's done, even more confusing to me. I mean, he 
knows better than to rely so much on anecdotes   and his kind of clinical experience with athletes. 
And he should know that guidelines are not based   on anecdotes or even clinical observation. That's 
what research is for, to see if there is really a   connection between testosterone and saturated 
fat, for instance. Also confusing, he really   emphasizes his own experience. [Andrew] "My blood 
lipids are great, thank you. And I'll be happy to   share my blood lipid profiles, and show I've done 
the experiment." Who gives a [ __ ], man? I mean,   again, this is what research is for. One person's 
experience tells us one thing: it tells us about   one person's experience.

But since Dr. Huberman 
loves anecdotes so much, my partner, my husband,   has been vegan for more than 15 years. We have 
3 beautiful children together. Gosh, sometimes,   like, I want to plaster them all over my channel! 
A six-year-old, three-year-old, and a six month   old. And we had no trouble conceiving. The first 
two took one month, and then six month old, it was   four months until I got pregnant. And there are 
lots of other vegan parents out there. So clearly,   not being vegan is "nutritional castration" and 
"absolutely deadly" for the reproductive system,   right? Has this guy been interviewed by Joe Rogan? 
Like, you know he has. Oh yep, he has. I shouldn't   have called him a quack. He seems like a nice guy, 
and I like that he said he's not promoting lots of   saturated fat.

[Andrew] "I never said to consume 
butter in large amounts." But it seems like he,   again, is really interested in anecdotes, which is 
just weird, and seems to base recommendations off   of that. He really seemingly wants to come off as 
an authority figure, which I get, he apparently is   actually working with patients on improving their 
testosterone. But again, you don't make confident   claims based on that, recommending supplements 
that have virtually no evidence for what he's   claiming, that they improve testosterone. It 
seems like he is very easily influenced by   minimal data. So not a quack, but, you know, 
just just be careful, right. Just be careful   listening to people. Always go for an outside 
source. Always check consensus, right, Harvard   health is really good. Again,

you so much for watching everybody! I hope you   enjoyed that. I would love to know your thoughts 
on testosterone and veganism, or fertility in   general. I was really interested in, partly 
why this took me longer than it should have,   I was reading a lot into the study that looked at 
a healthy plant-based diet and an unhealthy one.   They were using this plant-based diet index 
from a different study that some researchers   developed. And yeah, it's just very interesting. 
So I spent way too much time looking at that,   and it really was not relevant to this, but that's 
that's what happens every time. Learning is too   fun, I can't help it. Like the video if you 
liked it. Subscribe. You can hit the bell if   you want to be notified every time I upload a 
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I've already uploaded the 
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