No, I'm not a nutritionist and I don't play one on TV, but I AM an optimization geek and a very huge part of getting optimal results from your training is to eat to support your goals. So I pay attention.
While micromanaging intake (measuring everything) is only for obsessives like- well, me - I think having some nutritional awareness and a framework to use as basis for your diet is a good thing. Stops mindless eating and snacking out of boredom from happening (as much) - when you're using one particular nutrition lens or diet (Paleo, vegetarianism, veganism, 'eat clean', whatever) to sort out your diet you wind up removing the highly processed and calorie-dense foods from your diet most of the time.
Which is good as far as it goes, but sometimes the end result isn't quite what you had in mind for youself.
What if I invited you to start on a diet that ensured you either started suffering from chronic malnutrition and increased your risk and susceptibility to several diseases or practicaly had to live off highly processed industrial supplements to counter the damaging effect of your lifestyle?
Doesn't sound like a good idea, does it?
Okay then - how about I invite you to take up Veganism?
Sound healthy you say? Ah, but - veganism is that diet that either leves you chronically malnourished or dependent on supplements to stay alive.
Yeah, no thanks.
Vegetarianism - lacto-ovo, or pesectarianism are subsets ("I'm a vegetarian who eats eggs/dairy", or "i'm a vegetarian who eats fish" respectively) is a completely unnatural diet for humans, our genome evolved to get at least 50% if not more of our daily calories from animal sources.
Of course we also evolved to have kids at 14 and die of old age by 35, so the evolutionary argument only goes so far, but realise that when you're thinking of cutting out animal products from your diet, you're acting contrary to the nutritional profile that's optimal for your from an evolutionary perspective, so you're going to have to start obsessing about nutrition and diet to an amazing degree if you want to not just survive but thrive on a vegan or vegetarian diet.
Read What every Vegan should know about Vitamin B12.
If you don't supplement with it, you're screwed. A diet that requires that you live off supplements for the rest of your life does not qualify as natural in my book.
There's a number of vegetarian and even vegan athletes so it's doable to maintain the lifestyle and perform reasonbly well in a sport, but it does require a lot more dedication and planning than just going with the natural predisposition of your evolutionary blueprint.
How about Raw-foodism? Surely cooking your food is unnatural?
Bah. The earliest archeological trace evidence of humans using fire is about 500,000-600,000 years old, and the earliest evidence of actual cooking is approximately 125,000 years old.
Since even the most pessimistic estimate for how long we need to genetically adapt to something is 50,000 years and the most realistic that includes the effects of cultural forcing and smaller population groups give 1,150 and 3,000-5,000 years as estimates, humans have cooked food for 25-108 times longer than it would take our genome to adapt to cooked food.
From the PoV of your evolutionary blueprint, it's raw food that's unnatural; and our ability to live off it in extreme circumstances is more a testament to humanity's outstanding adaptability than anything else.
Actually, cooking is a large part of why humans were able to conquer the planet. Cooking our food killed parasites and infectious agents in it and allowed us to eat anything we came across without fear of fluke, flu, salmonella, e. coli or other nasties.
Uh, okay, but surely at least organic food must be healthier?
Nope. Organic growing is an offshoot of "vitalism", the magical thinking that there's some special life-energy in living things that goes beyond the various chemical constituents of it. Which leads to using 'organic fertilizer' - a code word for manure - on your plants.
Organic farming doesn't preclude the use of some of the most lethal pesticides known to man, and it's pesticide residue that's potentially harmful from any farming practice. In fact, several of the inorganic pesticides have shorter half-lives and are less lethal to humans than the organics.
Don't buy the hype. Slapping "organic" on the label doesn't make it healthier or safer. You're still trusting the farmer to have done a good job with his products - make sure you choose wisely.