Ask the Nutritionist: Are The So-Called Good Fats Really Good For You?

Q: Because I’m a vegetarian, everyone thinks my diet is fat-free. I know fats lurk in lots of foods, though. But aren’t there some “good” fats?

A: You’re right, fats turn up in many foods (and yes, in some healthy ones). A quick way to spot them is to look for the foods that tend to be highest in calories, as those are also highest in fat. That’s because fat is a concentrated source of calories. One gram of fat contains 9 calories—more than double the calories in one gram of protein or carbohydrate (there are 4 calories in each). So adding even small amounts of fat to recipes can substantially increase the total number of calories.

Now, generally, fats that come from plant sources are better for you than fats from animal sources. Plant fats—such as the oils in olives, nuts, seeds, flax and avocados—are rich sources of vitamin E, phytochemicals (protective or disease-fighting plant compounds) and essential fatty acids (EFAs), which include omega-3 fatty acids and are heart-healthy monounsaturated fats. You’ve likely heard of the Mediterranean diet, which suggests that people who eat like those in countries surrounding the Mediterranean Sea stay trim despite eating sizable amounts of these good plant fats, along with whole grains and plenty of fruits and vegetables.

There’s no single recommendation for the amount of vegetable fat to include in your diet. Just like anything, if you overdo even good-for-you fats, you’ll pay a health price in excessive calories and fat grams. Although fat improves the flavor of foods (most of us like the taste of it), extra fat doesn’t mean that meals will be extra filling. That’s one of the pitfalls of high-fat foods. Many low-cal foods, such as whole grains and veggies, keep you full longer because they’re full of dense, nutritious complex carbs and are high in fiber. People get full and stop eating before they’ve consumed a lot of calories from these foods.

Think of it this way: You eat a serving of ice cream; you eat a large orange. You’ll likely feel equally full, but you’ve taken in far fewer calories eating the orange. Aim to get about 10 to 30 percent of your calories from plant fats, excluding partially hydrogenated oils (more on that shortly). For weight control, the lower end of the range is better. For instance, instead of snacking on nuts and seeds by the handful, sprinkle a tablespoon or so on salads and casseroles. You’ll still enjoy their flavor and their wholesome attributes, just without loads of extra fat.

Q: Are there any totally bad fats?

A: Partially hydrogenated oils. These specially processed oils—originally designed to have a long shelf life—have turned out to contain trans fat, a substance now known to raise cholesterol levels and increase the risk of coronary artery disease. According to a September 2002 report issued by the Institute of Medicine, there is no safe level of trans fat intake. Nutrition labels now list how much trans fat an item contains. You’ll see it listed mainly on highly processed foods and in most brands of margarine and solid shortening—ingredients that are often called for in recipes for pie crusts, biscuits, cookies, cakes and pastries.

Q: What other ingredients besides excessive fats should I keep an eye out for?

A: Something else that can sneak up on you by adding calories without bulk—or nutrients—is sugar. One cup of hot tea, for instance, is calorie-free. But stir in a couple of teaspoons of sugar, and the same cup now has about 30 calories. Drink three cups of tea a day, and you may consume an extra 90 calories. Whatever your sweetener pleasure—sugar, honey, maple syrup or corn syrup—the goal is the same: Keep your intake to a minimum since they provide little in the way of nutrition.

The US Department of Agriculture recommends that people eating 2,000 calories per day limit their intake of added sugar to 10 teaspoons daily. That may sound like a lot but it’s actually about half the amount of sugar that most of us currently consume. Our chart on the right lists other common ingredients that add substantial calories to foods. If you’re cooking at home, use these ingredients with a light hand. If you’re eating out, your meal may well contain a lot of them.

For instance, flavored coffees are often full of super-sweet syrups, and pasta dishes can be smothered in a layer of melted mozzarella cheese. If in doubt, ask your server about how a dish is prepared, and request changes, or just change your order, when necessary. The bottom line: In your diet, emphasize plant fats that are as close to their natural state as possible. That means limiting fried foods and totally avoiding partially hydrogenated oils. Because of the calories, it also makes sense to go easy on even plant oils and spreads (such as trans fat–free margarine) and added sugars.