The Skinny on Fat
by Jessi Pergolotti (B.S. Nutrition '14)
You've shied away from eating it and worked on the treadmill to burn it off. But fat, it turns out, can be your friend. "Your body needs it in order to function," says Barbara Roberts, MD, director of the Women's Cardiac Center at the Miriam Hospital in Providence and author of How to Keep from Breaking Your Heart. "Fats help you absorb vitamins A, D, and E, and they are vital for your nervous system." Not only that, women who ate a Mediterranean diet filled with healthy monounsaturated fat lowered their risk of heart disease by 29 percent, according to a new study in Circulation.
The Good: Unsaturated Fats
What they do: These fats, known as MUFAs, raise good HDL cholesterol, lower bad LDL cholesterol, and protect against the buildup of plaque in your arteries. They also help prevent belly fat, according to research. Where you'll find them: In olive oil and olives, canola oil, almonds, cashews, peanuts, peanut butter, sesame seeds, and avocados. How much you need: Most of the fat you eat should be unsaturated, like MUFAs. "Just two to three tablespoons of olive oil a day can raise HDL levels and protect against heart disease," says Dr. Roberts.
What they do: In addition to lowering your LDL, these fats contain essential omega-3 fatty acids -- which boost brain function and may help strengthen your immune system and improve your mood -- and omega-6 fatty acids, which in small amounts can keep skin and eyes healthy. Where you'll find them: Omega-3s are primarily in fish like salmon, mackerel, and herring, as well as canola oil, flaxseed, walnuts, and tofu. Omega-6s are in corn and safflower oil, corn-fed chicken and beef, and farmed fish. How much you need: Most of the polys you eat should be omega-3s. Too much omega-6 can lead to inflammation, which is linked to heart disease. Trade vegetable oil for olive and canola oils, and eat grass-fed beef and wild-caught fish.
The Bad: Saturated Fats
What they do: They raise cholesterol levels and increase your risk of heart disease. Where you'll find them: In meat and poultry, in dairy products like cream, butter, and whole and 2 percent milk, and in some plant foods like coconut and palm oil. How much you need: Limit saturated fat to less than 10 percent of your total daily calories. One easy way to cut back: "Remove any hard fat you can see, such as the skin on chicken," says Christine Gerbstadt, MD, RD, a spokesperson for the American Dietetic Association.
The Ugly: Trans Fats
What they do: Made from unsaturated fat that's been chemically altered to prolong the shelf life of packaged foods, trans fats raise bad LDL and lower good HDL, increasing inflammation throughout the body. "They 100 percent promote heart disease," says Dr. Gerbstadt.
Where you'll find them: In shortening, margarine, doughnuts, french fries, and processed foods such as crackers, cookies, chips, and cakes.
How much you need: Zero. But know this: The FDA allows food manufacturers to claim that a product contains "zero trans fats" if one serving of it has 0.5 grams of trans fats or less. "That means if you eat more than one serving, you could be getting a gram or more," warns Dr. Gerbstadt. Before buying foods, check the ingredient labels for "partially hydrogenated vegetable oil" -- trans fats' sneaky pseudonym.