Are fats so bad?

For years, fat was a dirty word in the dietary world. After World War II, large studies established links between saturated fat and heart disease. Most dietary experts advised people to reduce their fat intake, not only because of the heart connection, but also because fat has more calories per gram than protein or carbohydrate and was assumed to contribute more to weight gain. Many people did so, but they often replaced the lost calories with large amounts of carbohydrates— especially refined carbohydrates. They also stopped eating healthy fats, like olive and canola oils. Instead of helping us slim down, the decline in fat consumption was accompanied by higher rates of overweight and obesity.

What went awry? As it turns out, the "all fat is bad" message was wrong. Foods that contain fat help fill you up, so you stop eating earlier. More important, not all fats are alike. Saturated fat, found mainly in meat and dairy foods, contributes to clogged arteries and cardiovascular disease. But monounsaturated and polyunsaturated fats, found in plants and healthful oils, actually protect your health by improving your cholesterol profile . Fat has little direct effect on blood sugar levels. It is a major energy source for your body, and it helps you absorb certain vitamins and nutrients.

Another type of fat needed for a variety of vital physiological functions is the family of omega-3 unsaturated fats. Your body can't make these on its own; it must get them from food. Omega-3s may help prevent heart disease and stroke. There is emerging evidence that omega-3s may also help beta cells in the pancreas improve their production of insulin. Good sources of omega-3s include fatty fish such as salmon, tuna, sardines, and mackerel. Flaxseeds, walnuts, wheat germ, canola oil, unhydrogenated soybean oil, and flaxseed oil are also rich in omega-3s.

Trans fats are the worst fats for your health. These fats are made when hydrogen is added to healthy unsaturated fats to solidify them and make them less likely to spoil. Trans fats raise harmful LDL cholesterol, lower beneficial HDL cholesterol, increase inflammation, and make blood more likely to clot. To avoid them, look for products that have a zero on the "trans fat" line in the Nutrition Facts box. The FDA has ruled that "partially hydrogenated" oils, the main source of trans fats in the American food supply, are no longer "generally recognized as safe" and that food companies must stop using them by 2018. Until then, it's a good idea to stay away from foods that list "partially hydrogenated" oils in their ingredient lists.

The current Dietary Guidelines for Americans recommend that adults get 20% to 35% of their daily calories from fat and limit saturated fat to under 10%of daily calories. The American Diabetes Association, while generally supporting the Dietary Guidelines, has backed away from giving this type of specific guideline, saying there isn't much evidence behind those numbers. Whenever possible, choose healthy polyunsaturated and monounsaturated fats over unhealthy trans fats and saturated fats.

Diet and blood cholesterol level

There is some evidence that food has a greater effect on the level of harmful LDL cholesterol in people with diabetes than in other people. For that reason, it is especially important to make food choices that won't increase your LDL.

Start by limiting the amount of trans and saturated fats you eat, since your body uses these fats as building blocks to make cholesterol. Higher-fat cuts of red meat are high in saturated fat, as are some dairy foods, such as cheese, butter, and ice cream. Steer clear of trans fats by reading food labels and avoiding deep-fried foods when eating out. The cooking fats that contain trans fat are certain commercial frying oils, partially hydrogenated vegetable oils, vegetable shortening, margarine, griddle shortening, and vegetable ghee, a fat commonly used to cook Indian food. Types of oils that are preferable for frying include canola, soybean, sunflower, and olive oils.

Cutting back on foods that contain high amounts of cholesterol—such as liver, egg yolks, squid, shrimp, and some meat and dairy products—may also help keep your cholesterol level in check, although for most people, cholesterol-rich foods have only a minor effect on their blood cholesterol levels.

Switching from refined grains and foods made from them (like white rice and white bread) to whole grains and foods made from them can also improve cholesterol levels.