Most foods contain a mixture of fats and the idea is to strike a balance between them. According to the American Dietetic Association, Americans consume close to 40 percent of their calories from fat. But according to the American Heart Association, total fat intake should be between 25 – 30 percent of total calories and this amount should come mainly from monounsaturated and polyunsaturated fats.
There are four major dietary fats in food: saturated, trans, monounsaturated and polyunsaturated.  They each have different chemical structures and physical properties.  Saturated and trans fats tend to be solid at room temperature (like a stick of butter), while monounsaturated and polyunsaturated fats tend to be more liquid (like vegetable oil).
While the human body definitely needs fat, not all fats are created equal. They do, however, share some common traits.
All fats contain nine calories per gram, compared to four calories per gram for protein and carbohydrate so they tend to add up more quickly. They support cell growth, protect organs, help keep your body warm, absorb vitamins and produce hormones.
Saturated fats and trans fats, in excess, can raise cholesterol levels and increase the risk of heart disease and stroke. They increase the risk of some cancers, high blood pressure, diabetes and obesity.
Saturated fats are found in meat, cheese, cream, butter and other whole fat dairy products. Some oils, palm, palm kernel and coconut also contain saturated fat.
Trans fats are found in bakery items, fried foods, snack foods and traditional stick margarine and may show up in the ingredient list as “partially hydrogenated” or “shortening”. The Food and Drug Administration has made it mandatory that trans fats be listed in the nutrition facts label. Food manufacturers can claim zero trans fats if the amount is 0.5 grams or less so reading food label labels of things consumed is both informative and helpful.
Monounsaturated fats can be found in vegetable oils such as olive and canola oils and many nuts and seeds like almonds, peanuts and sesame seeds. Peanut butter and avocadoes are also good sources.
Polyunsaturated fats can be found in oils such as soybean and corn oils and in many nuts and seeds such as walnuts and sunflower seeds. Fatty fish like salmon and trout are also good sources. Polyunsaturated fats include omega-3 and omega-6, essential fats that your body needs but can’t produce naturally.
Eating foods with a moderate amount of fat is definitely part of a healthy diet.  Just remember to balance the amount of calories you eat with the amount of calories you burn.  Aim to eat more vegetables, fruits, whole-grain and high-fiber foods, fat-free and low-fat dairy products, lean meats, poultry, and fish (at least twice a week).  Doing so means that your diet will be low in both saturated fats and trans fats.