My natural diet is different from my best friend (First Nations origins). I do best on mostly veggies with whole-grains, eggs, dairy and a little fish. I'm European origins mostly and that's what we've eaten for thousands of years. Admittedly peasants didn't get as much of the dairy/meat as the rich folks, but they ate it too. So for me, mostly vegetarian does the trick.
For my First Nations friend, she does best on meat plus fruit and veggies. She is opposed to a low fat diet, liking grass fed butter. She does not do well on grains. Essentially, she has found by trial and error that what works best for her is closer to her ancestral diet also.
Now, two people don't make a scientific proof, and folks have random allergies and reasons for not wanting certain things and that's okay. I just think that the mythical "magic diet" is just that - a myth. We're all different!
I would say, find what works for your body - your biology. Personally I find myself getting in better shape when I don't weigh myself or calorie count; I know how I'm doing by my reflection in the mirror and how my clothes fit. I eat mostly healthy choices (wholegrains) but have something sweet every day (we Brits say "a little bit of what you fancy does you good!) I don't stick to set meal times (eat when I'm hungry) I walk the dog most days (some Vancouver rain is monsoon quality!).
I think with some listening to your own body you can figure out what you need. Just like most recipes work when you put together flavours you like - these things are actually just about having the courage to try a way that works for you and stop googling for answers.