Types of fat

When you eat fat, your body breaks it into smaller parts called fatty acids. These fall into two categories: saturated and unsaturated fatty acids.

Saturated fats have a stiff chemical structure and are often solid at room temperature. Foods that have saturated fats include lard, beef tallow, meat, and dairy foods such as whole milk, butter, some cheese and yogurts. Coconut oil and palm oil also are high in saturated fats.

Unsaturated fats have a more flexible chemical structure. When separated from food, they are often liquid at room temperature. Unsaturated fats can be either monounsaturated or polyunsaturated. Omega-3 and omega-6 fatty acids are polyunsaturated.

Examples of unsaturated fats include:

• Avacados and avocado oils.
• Olives and extra-virgin olive oil.
• Nuts, such as almonds, cashews, peanuts and hazelnuts.
• Seeds, such as flaxseed, hemp seed and chia seed.
• Soybeans, edamame and tofu.
• Safflower, sunflower and corn oil.
• Canola, soybean, flaxseed and walnut oil.
• Seafood, such as shrimp, salmon, anchovies, sardines and tuna.

Trans fats naturally occur in meat and dairy products from grazing animals. But most trans fats in food come from plant oils that are chemically changed to be semisolid fats. This process is called partial hydrogenation.

Trans fats are often found in processed foods, such as fast food, commercial baked goods, stick margarine and foods that are deep fried. This type of fat is less expensive than other fats and gives food a long shelf life.

In the United States, trans fats cannot be used in food production. Food makers in other countries may still use this ingredient.