Basically, unsaturated fats are the go-to fats you'll want to look for on your food nutrition labels, and omega-3 fatty acids are kings of the hill. "These fats are considered 'good' because they help protect against heart disease, encourage brain strength, and build healthy skin, hair, and nails," says Lewis. You'll find this stuff in avocados, nuts, olive oil, and fatty fish such as tuna and salmon. On the heart-clogger list, you'll find saturated fats (keep to a minimum) and trans fats (avoid altogether).
Carbs and hormones play a part
Many low-carb diets often encourage consumption of good-fat foods (and, by definition, foods that don't have a bunch of junk carbs), which means that your body will turn to your fat stores for fuel because you don't have a ton of low-quality carbs -- like Twinkies -- on board.