Or some may need to vary it a lot. I ate the way you describe for most of my adult life, but still ended up diabetic, overweight, and lethargic. These days, I eat all the "wrong" foods (according to the experts)... no fruits or grains whatsoever, limited vegetables, and moderate amounts of fatty dairy and meat. The first thing that happened is that I lost almost 100 pounds, gained energy I didn't know I had, and got my blood sugar and cholesterol under control. Even my doctor was completely taken aback, and told me to keep up whatever it was I was doing.
And yes, I also get plenty of exercise, fresh air, and sleep.
One needs to keep an open mind, and not necessarily poo-poo what works for some of us.