I discovered a while ago that a high fat diet made me feel better, experience increased focus, and benefit from all day long energy. When I was training for Ironman France I got up to about 10,000 calories per day of which about 85% of it was from carbohydrates. That was kind of ok since I was easily burning it off every day, but when I took a break after the event, within a couple of weeks I started to experience massive, addiction like, sugar cravings. I even had withdrawal symptoms like headaches, mood swings, etc...I started filling the holes in my diet with good fats and immediately began to see some incredible results. At this point I enjoy a diet of roughly 4,000 calories per day at around 65% fat and I feel amazing. A lot of the hardcore data for this post - beyond my own experiences - comes from two amazing sources, Dave Asprey of the Bulletproof Executive, and Mark Sisson of Mark's Daily Apple.
What do I mean by good fats?
Things like nuts, avocado, fish, olive oil, egg yolks, grass-fed meat, and my personal favorite, grass-fed butter. Good fats can have an anti-inflammatory effect as well as help manage insulin levels. Our bodies fuel more efficiently on fats as do our brains. You'll feel more satisfied for longer and actually feel smarter and more focused. What more could you ask for? I can tell you from personal experience that adding a slab of butter to my breakfast eggs or salad dressing is a good feeling.
It gets beaten into our heads that fats are bad and so many diets focus on low fats. Good fats will not make you fat, they will not raise your cholesterol, they will not lead to heart disease, and they will not negatively affect your performance. Not only do good fats NOT do any of these bad things, they actually have all sorts of added benefits. At 9 calories per gram, fat is the densest nutrient source with some fats containing the highest levels of certain vitamins. Fats are also an essential tool in the absorption of fat soluble vitamins that you get from other foods.
So add some extra olive oil to your salad, put a big hunk of grass-fed pot roast on a pillow of guacamole, and slather your omelet in grass fed butter, I promise you won't regret it.