The Skinny On Fat (Source: The Mayo Clinic)

Believe it or not, fat is a necessary part of a healthy diet. It is essential for certain body functions, and it helps our bodies absorb fat soluble vitamins. But, all fats are not created equal. Healthy fats can help to lower LDL, or bad cholesterol. Some have also been shown to help lower blood pressure. Harmful fats have been shown to raise bad cholesterol, which leads to increased risk for heart attack, high blood pressure, and stroke. The following is a list of healthy and harmful fats, and the foods that contain them.

Healthy Fats

• Monounsaturated – Liquid at room temperature. Olive oil, peanut oil, canola oil, avocados, and most nuts.
• Polyunsaturated – Liquid at room temperature. Sunflower oil, corn oil, safflower oil, soy oil, and cottonseed oil
• Omega-3 Fatty Acids – These are polyunsaturated fats found mostly in cold water fish like salmon and mackerel. Flaxseeds and walnuts also have Omega-3s.

Harmful Fats

• Saturated Fats – Solid at room temperature. Usually come from animal sources: Butter, red meat, poultry. Also found in coconut and palm oil.
• Trans Fats – These are vegetable oils that have had hydrogen added to them. This increases the shelf life of the oil. These fats are common in fried foods (French fries, donuts, etc.), shortening, margarine, and commercially baked cookies, cakes, and crackers.
  

Because fats are calorie dense (9 calories per gram compared to 4 calories per gram for protein and carbohydrates), they should only make up 30% of you daily caloric intake. The USDA recommends that saturated fats make up no more than 10% of your daily caloric intake, and the American Heart Association recommends that Trans fats make up no more than 1% of your daily calories.

Source: The Mayo Clinic