Everyone is different. I thrive on eggs, bacon, and coffee breakfasts. I make sure the bacon is full fat, eggs cooked in the bacon fat or with grass fed butter. Grass fed butter and coconut oil in the coffee.
Oatmeal, fruit, carbs at breakfast would send my blood sugar soaring then crashing creating two impacts: extreme hunger, never making it to lunch. And it would put my body into fat storage mode rather than what I do now putting it into fat burning mode.
Just my experience, individual mileage very important. Experiment I say.
Only posting to echo YoYoMa and to say that yes parts of the brain only can use glucose but you will produce way more than enough on a low carb high fat diet. Also increasing research into the high rates of depression the last 100 years being due in part to cutting out fat especially saturated fat.
Many people in the nutrition communities I belong to report their best ever mental health on high fat diets. And there are increasing numbers of reports of people with bipolar and other mental disorders being helped even cured for the first time in their lives on high fat low carb. I can say I now get no mental crashes at all 24/7, best mood, and mental clarity of my life.
This article below explains why. I believe, and people of course can disagree, that humans evolved on high fat diets. Our brains thrive on them. My opinion of course.
http://www.psychologytoday.com/blog/...-brain-ketones