My happiest start to a day involves protein in the form of a steak. A standard carbohydrate North American breakfast would only make me sick. You may thrive on a high carbohydrate breakfast of pancakes or bagels. The thought of red meat so early in the morning may nauseate you.
So ... whose diet is best? I'd say they both are. Mine works for me as yours does for you.
If something I eat makes me bilious, if I end up hungrier than I was before I ate ... this food is contraindicated. But if I'm left satisfied, clear-headed, energetic, this is something I'll eat again.
If your meals leave you wilting or in pain, if your weight is creeping up, it's time to re-evaluate.
I don't think one diet can fit all, if only because too many food intolerances and allergies must be taken into account.
People flourishing on a high protein or high fat diet doubt that someone can be healthy eating whole grains. And the person who feels most vibrant on complex carbohydrates may be suspicious of the hypothesis that meat is good for anyone.
But different people react differently to different foods.
Nightshades like potatoes, peppers and tomatoes, are very bad for some. Nightshades may not cause an immediate reaction but can later trigger acute joint and muscle pain.
Fructose malabsorption causes fermentation in the large intestine culminating in irritable bowel syndrome (IBS) symptoms. People with fructose malabsorption can handle gluten but not wheat, which means they can usually eat other grains. They need to avoid onions, green and yellow beans, asparagus and honey, and go easy on the fruit.
Dairy. Grains. Gluten. These are well-known on the intolerance list. Many people can't abide them, feeling sick and pasty if they eat them. They'll have joint and muscle pain and gastric upheaval. They may feel anxious and unable to think clearly.
And yet. There are those who really do feel good living on carbohydrates. I'll take your word for it, if you'll believe me when I say I can't eat the stuff.
I don't think that the on-going debate about which diet is best can ever reach a satisfactory conclusion. How can it?