Some of you aren't going to like me saying this, but I sincerely believe that plant-based diets are going to take over the men's health community eventually here in the U.S., a space traditionally dominated by Paleo and Low Carb. And I believe it's going to be sooner rather than later. I think I am somewhat unusual in the sense that I am plant-based (whole foods vegan) and yet have read a large body of Paleo and Low Carb writing and research. In spite of that, I still think meat eating is going to dramatically decrease over the next 20 years and plant based eating will rise to ascendancy rapidly.
First of all, Low Carb Diets are already dying a fairly quick death for all the reasons I outline here: The Best Summary of the Research-Backed Dangers of Low Carb Diets. That leaves the Americanized version of Paleo, and I think it, too, will rapidly die out and be replaced by the following three types of diets:
a) Vegan and Plant Based. These diets are 100% plant based. Generally speaking, plant based means now someone who is vegan but eats only whole plant foods.
b) Vegetarians. Vegetarians generally, eat 90+% plants and 10% a combination of eggs or dairy.
c) Flexitarian. If you feel that you have to have some meat, then there is a diet called flexitarian. This simply means someone who eats 90+% plants and 10% meat, eggs or dairy.
I am sure that some if not most of you are very skeptical, but I think you'll see why I say this when I explain Five Great Reasons to Go At Least 90+% Plant-Based:
1. Testosterone. Did you know that the best study that we have to date shows that vegetarians have testosterone equal to meat eaters and that vegans have the highest total testosterone? I discuss the study in detail in my page on Testosterone and Vegetarianism. Now vegans actually probably don't have higher free testosterone, since their SHBG will tend to be a bit higher. But the real point is that you can eat a TON of plants and no animals and have total testosterone at least equal to the meat eaters around you. Yes, it is a complete myth that plant foods lower testosterone, and there is no research whatsoever to support the ludicrous statements that I hear to the contrary.
2. Nitric Oxide and Blood Flow. Let me give you the #1 reason that diets with at least 90% plant are going to win with men: plants are incredibly powerful boosters of nitric oxide and blood flow and animal foods and meat suck at it. This is the reason I wrote my book The Peak Erectile Strength Diet. In my book - and at the time I wrote I was the only one who wrote about the subject as far as I know - I documented one reason after another that plant foods were such powerful aids in erectile strength. They are packed with nitrates, flavonoids, polyphenols, anti-inflammatories, antioxidants - the list goes on and on - and many other phytochemicals that protect your arteries from plaque and boost nitric oxide.
This is in direct contrast with animal foods which have no such ability whatsoever. If you sit down and eat a steak or chicken, will it boost your blood flow and lower your blood pressure? No way! Quite the opposite. This is a unique property of plant foods, and again you can read about it in my book.
CRITICAL POINT: So why is this so important? Because guys are all about erections and plant foods can be a life saver in the bedroom, especially as you age. If you eat a ton of plant foods, you boost your nitric oxide AND you get to keep your testosterone. Is this an unbeatable formula or what?
T + NO = Max Erectile Strength
So what's not to like?! You basically get to have your cake and eat it too.
Again, men are short-changing themselves in the bedroom with low carb and certain Paleo Diets that load up on animal foods. Yes, young guys can eat that way and have great erections because they have a lot of buffer and nice clean arteries. Most middle-aged and senior men have no such "luxury."
3. Gut Health. One of the things that just floors me is that men don't stop and think about how much we look like an ape. We are incredibly similar both internally and externally. Nowhere is that more apparent than in our GI tract. Our gut, in particular, is almost totally that of a herbivore. It is long, twisting and convoluted. This in direct contrast with the typical carnivore that has a short and straight gut. It's basically a pipe to shoot that stuff out as rapidly as possible.
Stop and think about why this is the case: iff you eat a a large amount of meat, the contents of the bowel are going to be a rapidly putrifying, slowly moving, fatty blob. This mass needs to "get in and get out" which is why a carnivore's gut makes that so easy.
Plant eaters instead have a long twisting gut that requires a lot of fiber and bulk for obvious reasons. What a disaster to shove a steaming pile of fat and meat into our poor gut, where it moves slowly and painfully through our herbivore-like GI tract! No wonder Crohn's, diverticulitis, IBS, colitis, etc. are at epidemic levels. And no wonder our gut flora is a disaster. One study after another has come out about the important of gut flora on health. And high fiber, whole foods, plant-based diets are king in this area.
If you don't have two easy, non runny and non-constipated bowel movements per day, then you need to get to a plant-based regimen.
4. Sustainability. I get amused with people who are worried about the fact that we have an aging population. I'm not being callous to demographic effects on the economy, but this is just the beginning! There are now huge players in anti-aging, regenerative medicine and life extension that are going to revolutionize and extend both healthspan and lifespan very soon. And I am not talking about supplements here: I am talking CRISPR (gene editing), sterm cell therapies, nano technology and so on.
Already we already curing several types of blood cancer. And the progress against cancer has been so impressive that it is not at all unreasonable to believe that cancer will be completely defeated in the next forty years. As I write this, several of the nastiest genetic diseases have clinical trials underway to be eradicated with gene editing. This research is going to rapidly accelerate.
So how does this fit into an argument for plant foods? Because as the population ages, there will simply be no way to feed men significant percentages of animal foods and products. At some point we all have to admit that plant foods are much more sustainable. Check out these stats as examples:
--Livestock produces more greenhouse gases than all cars, planes and trucks combined.
--To produce a pound of meat generally takes between 500 and 2000 gallons of water. To produce a pound of most plant foods is between 30 and 200 gallons.
--"In the United States, more than 9 billion livestock are maintained to supply the animal protein consumed each year." 
--"This livestock population on average outweighs the US human population by about 5 times." 
--"At present, the US livestock population consumes more than 7 times as much grain as is consumed directly by the entire American population." 
--"The amount of grains fed to US livestock is sufficient to feed about 840 million people who follow a plant-based diet." 
I know lots of men on my forum who are into sustainable energy sources and get excited to hear about advances in solar power and other similar technologies. What they don't realize is that shifting to a largely plant-based diet can have easily the same level of impact in achieving sustainability on our planet.
5. Supercultures. There are a handful of supercultures that have a unique combination of qualities: they live without chronic disease (heart attack, autoimmune disorders, stroke or cancer) and also have extreme longevity. These cultures typically have a high percentage of centenarians and men and women in their 90's are usually very alert and mentally and physically active. The Tarahumara of northern Mexico are a great example of this. John Robbins provides four other examples in his book, which I review here: Healthy at 100. All of the supercultures have several things in common, but one of them are diets that are very high in and based upon plants. This is powerful evidence in my opinion that optimal performance and longevity is obtained with a 90+% plant-based diet.
So get busy and choose one of those diets and get started! Solid testosterone, high nitric oxide, great gut health and maximum longevity. What's not to like?