Once you know how much carbohydrate and protein you need in your diet, the rest of the calories will come from fat. It is important to take care of your needs for essential fats, primarily Omega-3 fats, by eating foods such as fatty fish (like salmon) and flax seeds. Plant foods with a high amount of monounsaturated fat -- such as olives and olive oil, avocado, and nuts -- have been shown to have health benefits.
Even saturated fats, usually considered to be a damaging type of fat, haven't been shown to cause heart problems for most people eating low-carb diets. Still, a balance of fats, with an emphasis on sources such as olive oil and Omega-3 fats, is a good idea.
Many low-carb authors have been speaking out against trans fats for at least 10 years -- they have always been firmly against them.
