Generally avoiding fat is a 90s fad. It's not something you should still practice today. According to all of my training, you should aim to consume between 20-35% of your calories from fat each day. The typical, heavily-processed American diet contains around 35-40% fat. The food industry knows that fats enhance the flavor of food (just like sugars and salt), and so they pack processed food with fat. The industry wants to chemically inclined to crave their food. And they do a pretty dang good job of that.
Sidenote: if you want to learn more about how screwed up "Big Food" is, check these out: Food Inc., Forks Over Knives, Food Matters, SuperSize Me, Ingredients, The Future of Food, Hungry for Change, and Fat, Sick and Nearly Dead. Most of these are also on Netflix.
That being said, you also have an absolute minimum amount of fat (10%) that your body needs to function. While it's correct that you don't want to overdo it, you also don't want to under do it.
Fats are very calorie dense (9 calories per gram, as compared to 4 calories per gram for carbs and protein). So getting the right proportion of fat, if you're overdoing it, will help you to lose weight. Maintaining a healthy weight is known to reduce your risks of cancer and help you to live a longer, happier life.
It's not just the calories that are important. It's also the source of the fat. Natural, polyunsaturated fats are necessary will keep you feeling full for longer and they can help lower your cholesterol. Processed saturated and trans fats can raise your cholesterol and clog your arteries.
Unsaturated Fats (The Good Stuff)
- Oils (small portions, these are dense!)
Saturated Fats to Eat in Moderation
- Red meats
- Poultry skin
Trans Fats to Avoid
What you want to avoid is trans fats -- these are found in heavily processed foods, like fast food, cookies, crackers, frozen meals, etc.
When it comes to fats, you shouldn't live in fear. If you eat mostly plants and limit your processed foods and red meats, you really have nothing to be concerned about. As with most nutritional advice, the best path is usually the natural path.