How are bad fats and good fats different?

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Fats don't wear white hats and black hats, but some kinds are healthier, especially for your heart. So as a shorthand we divide them into "good" and "bad." Health experts recommend eating fewer saturated fats and trans fats, which tend to be solid or semi-solid at room temperature. These fats can raise blood cholesterol and damage heart health. On the other hand, liquid oils such as olive oil, canola oil and nut oils tend to contain more monounsaturated and polyunsaturated fats, which help keep cholesterol levels in check. Finally, fish contains a healthful polyunsaturated fat, called omega-3, which also has heart health benefits.
The amount and type of fat you ingest makes a significant difference to your health. Good fats of the polyunsaturated and monounsaturated variety may help lower cholesterol in the blood when consumed in place of bad fats.

Bad fats include saturated fats, derived mainly from animal sources, such as meat, cheese and other whole-milk dairy products. Even less healthy are trans fats, which are primarily produced through hydrogenation—a process that turns liquid vegetable oils into solids, such as the shortening and margarine often used in baked goods and snack foods. In general, fried food and fast food tend to be high in trans fats. Saturated-fat intake should not exceed 7 percent of daily calories (16 grams per day), and the latest research suggests trans fat consumption should be reduced to 1 percent of calories, if not avoided completely.
Michael T. Murray, ND
Naturopathic Medicine

What makes a fat "bad" or "good" has a lot to do with the function of fats in our cellular membranes. Our membranes are made mostly of fatty acids. What determines the type of fatty acid present in the cell membrane is the type of fat you consume. A diet consisting mostly of saturated fat, animal fatty acids, trans-fatty acids from margarine, shortening, and other sources of hydrogenated vegetable oils and that is high in cholesterol results in membranes that are much less fluid in nature than the membranes in a person who consumes optimal levels of unsaturated fatty acids. According to modern pathology, or the study of disease processes, an alteration in cell membrane function is the central factor in the development of virtually every disease. As it relates to diabetes, abnormal cell membrane structure due to eating the wrong types of fats leads to impaired insulin action. Without a healthy membrane, cells lose their ability to hold water, vital nutrients, and electrolytes. They also lose their ability to communicate with other cells and be controlled by regulating hormones, including insulin. Without the right type of fats in cell membranes, cells simply do not function properly. Considerable evidence indicates that cell membrane dysfunction is a critical factor in the development of many diseases.

Encyclopedia of Healing Foods

More About this Book

Encyclopedia of Healing Foods

From the bestselling authors of The Encyclopedia of Natural Medicine, the most comprehensive and practical guide available to the nutritional benefits and medicinal properties of virtually everything...
Dr. Michael Roizen, MD
Internal Medicine
Fat in foods, like bosses, come in two broad categories: Good and bad. Or, more specifically, those which are good for your well being and those who want you to suffer.

The strongest influence you can make on your levels of cholesterol (not to mention on you waist size) is by eating the right kinds of fats and banishing the wrong kinds.

Essentially, bad fats (such as saturated fat and trans fat) are the ones that are solid at room temperature—animal fat, butter, stick margarine, lard. They're the foods most associated with long-term weight gain and clogging your arteries. A serving size should have no more than 5 grams of those two villains combined.

The good fats (such as monounsaturated fat and polyunsaturated fat) and are the ones that are liquid at room temperature, but get thick when they get cold, like olive oil. They help raise your HDL "good" cholesterol levels to clear away the gook. Far more important than the calories of fat are what fatty acids can do to your cell functions, and how they influence arterial function and inflammation.
YOU: On A Diet Revised Edition: The Owner's Manual for Waist Management

More About this Book

YOU: On A Diet Revised Edition: The Owner's Manual for Waist Management

For the first time in our history, scientists are uncovering astounding medical evidence about dieting -- and why so many of us struggle with our weight and the size of our waists. Now researchers...

Continue Learning about Fats and Weight Loss

Lose Weight by Adding the Right Fat
Lose Weight by Adding the Right Fat
Former San Diego Charger’s lineman Nick Hardwick retired from the National Football League and from his daily 5,000-plus calorie diet that included sa...
Read More
How can low-fat foods prevent me from losing weight?
Dr. Mehmet Oz, MDDr. Mehmet Oz, MD
Many dieters fill their kitchens with foods branded as “low fat” -- but all too often that label...
More Answers
Which dietary fats should I avoid?
Manuel VillacortaManuel Villacorta
"Bad" fats include trans fat (which comes from partially hydrogenated oils). They are dubbed bad fat...
More Answers
How Does the Vanquish Fat Reduction Device Work to Melt Body Fat?
How Does the Vanquish Fat Reduction Device Work to Melt Body Fat?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.