Some Good Fats are fish or fish oil, coconut oil or cream (curry), avocados, butter, nuts and seeds, egg yolks and olive oil. Cold water fish have the most omega 3's (DHA and EPA are the ones we know we are after) of virtually any food source. Most of us don't eat fish at home all that often, so taking a fish oil supplement is common. They did a study on frozen fish sticks and it turns out the badness of breading and frying them more than balances out the goodness inherent in them, making it a net loss. Fish sticks don't count. Coconut oil and butter and egg yolks all have saturated fats in them, which we used to think were artery cloggers, but now we know better. These foods have medium chain fatty acids that are excellent high energy food (you do not have to eat sugar to have energy!), and natural antimicrobial effects. Avocados, nuts and seeds are absolutely packed with healthy fats and other nutrients. Olive oil has more studies showing it is good for you than any other food. You can eat it raw or cook with it. And it tastes yummy all by itself.
One interesting thing about fats is that we absorb antioxidants best when we eat them with fats. This applies whether you are getting your antioxidants from your coffee, a salad, a blueberry smoothie, or the red peppers in your fajitas. So when you are eating something with fat in it, think about eating your bright colored fruits and veggies at the same time. Perhaps this is why curry has turned out to be such a powerful antioxidant food: it is full of bright spices like tumeric and cinnamon, in combination with the creamy fat from coconuts. Antioxidants keep fats from going rancid, yes, even in your brain.
You know which ones are the Bad Fats, I bet. Trans and hydrogenated oils, corn oil, vegetable oil, soy oil, cheese. All animal fats are more inflammatory than vegetable fats. This is why so many people are transitioning toward mainly vegetable-based diets. Pork fat is about half monounsaturated, so it isn't as bad for you as people used to think. The worst thing for your brain is also probably the most addictive American food: potato chips. A burger and fries has also been showed to increase your level of brain inflammation immediately after consuming it.
There are a bunch of myths to shed. As of today you can stop believing that eggs cause high cholesterol, and that we'd be best off avoiding saturated fats, and that a low fat diet is the way to lose weight. All those things are turning out to be false. We never know for sure what science will tell us next, but we can be sure that the picture changes. It is possible to affect your brain health through your diet. You have the power of choice.