I know this forum is essentially just a sub-forum of bobybuilding.com and consists mostly of "making all kindz of gainz" bros and what not. Thus, I know such an opinion won't be popular around here, but I must say that if you want to live the healthiest life, you won't eat meat or cheese or drink milk.

For one thing, the heavier a diet is in protein, the higher your IGF-1 levels (an insulin signaling pathway). Yes, IGF-1 can be good for building muscle, but it also has been linked to All Cause Mortality (ACM) in a number of studies like this one. It has been linked to numerous cancers as well (a pretty significant risk of cancer, actually).

Indeed IGF-1 also has been linked to premature aging. This study and this study are good examples. It has been a primary focus of anti-aging researchers who have shown in roundworms, fruit flies and lab rats that the lower the IGF-1, the longer the animal lives (sometimes a significant increase in lifespan) and the fewer diseases they have including diabetes and cancer.

A lower level of IGF-1 is one of the primary benefits of intermittent fasting, which is believed to increase the lifespan of animals and humans. Researchers have long known that "calorie restriction" increased the lifespan of various species, but in the old days they didn't know exactly why it worked. Now we know that it's (mostly) IGF-1 -- the less you eat, the less IGF-1 will be circulating in your blood.

Outside of IGF-1, we all know about cholesterol, triglycerides and LDL-C increases because of meat consumption. While (dietary) cholesterol isn't the villain it used to be, there is still no doubt that trans fat and saturated fat is terrible for you. Study after study has shown this over and over again. Give me 100 vegans and 100 paleo people and let's test who has the highest triglyceride and LDL levels. Go to the paleo or keto subredit forums and look at all the people bitching about high cholesterol and LDL blood levels.

Now some people have the attitude "live fast, die young" which I can respect. Some people just want to get jacked in their 20's and are fine if they're dead by 50. It's the same with the fatass who says "I may die young, but at least I got to enjoy food." If that's your attitude, cool. You can stop reading.

But for those who want to maximize HEALTH and live the longest life their genes will allow, then a 100% plant diet is the only way, bros. It just is. Stop trying to claim your keto diet is healthy when hundreds of studies say exactly the opposite. Yes, you can lose fat, but you can lose fat with any calorie restricted diet. Being thin or even jacked doesn't mean you're healthy. Lots of bodybuilders have died in their 40's and 50's. Even Arnold himself has had bypass surgery. Yes taking steroids increases these risks (as well as cancer) significantly, but all that meat and protein doesn't help matters either. By the way, high levels of protein increases insulin sensitivity (no carbs aren't the only food that does this).

P.S. I am not a vegan fanatic who wants to "save the environment." I do it strictly for health reasons. I follow the science and the science says if you want to lower your risk of heart disease, cancer, diabetes and remain a normal body weight, you will eat plants and cut-out all meat.