Ok... I've read through a great deal of this thread, and just like any other nutrition debate, it has seemingly went nowhere.
So, with that being said, this is my personal account with a high protein-low carb food intake. Take it for what it is worth...
-no blood tests
-almost 36 years old
-very active... still train at a high intensity in speed/power events
This has been a gradual process over the last 3 years, with the most dramatic changes being the last 8 months. I'll cut straight to the chase...
About 8 months ago, I cut my 'whole grain' cereal out of my daily food intake, and replaced it with a high protein 'smoothie'...
1 cup of blueberries
3 raw eggs
1 cup of Fage 2% greek yogurt
1 tablespoon of Flax seed oil
1 scoop of whey protein
water
Within a few weeks, a small difference in body composition was being seen, and I was actually feeling better from a energy standpoint later in the morning.
My lunch 'routine' has remained virtually the same... chicken, black beans, a few veggies
Like my breakfast, my dinner has also changed. Up until about 4 months ago, I consumed a fair serving of rice, almost nightly. I enjoy sushi, so this is where most of it came from. Along with the sushi, I would also consume some beef, or guacamole. It might sound strange, but guac goes well with sushi. In the last 4 months, this has changed. My dinner now consists of a larger portion of protein (chicken breast or steak), fat (bacon), and my favorite Kale salad from the local grocery store. No rice, or bread.
The bacon is thick cut, and the usual serving is 5-6 slices.
OK, to the final point......... 1 month ago, I did a DEXA body composition scan - 6.7%. Previous tests have yielded on average 10%. My training is the best that it has been in years, and maybe the best it has ever been... literally, my baseline power-testing numbers are actually better than ever. Yes, ever.
I understand that I am relatively young, and obviously training at a higher level than the vast majority of folks my age. But, the food intake has absolutely had a positive impact on both the training, and ultimately, body composition.
I also understand that this does not mean that from a blood lipid standpoint, etc., that this is healthy. Like I said, I do not have blood test results to present.
This is just a very broad self-analysis of some changes that have taken place in my own food intake. The training has not changed, only the food intake... but, there has been a noticeable difference in body composition.
Just my experience, take it for what it's worth.