Read an Excerpt
The Good Fat, Bad Fat Counter
By Sheila Buff
St. Martin's PressCopyright © 2002 Sheila Buff
All rights reserved.
FATS AND FATOPHOBIA
Eat less fat! You hear the message endlessly from doctors, nutritionists, and everyone else. It's repeated in every media story about diet and health, it's taught in schools, and it's been embraced by the food industry. Yet even as we're all supposedly eating less fat, more Americans are overweight — one in two adults, one in four children — than ever before. What's going on here?
The problem is that the message is too simple. We're now in the grip of fatophobia — we see all fat as bad, no matter what.
The truth about fat is far more complex. Eating fat doesn't necessarily make you fat, and not all fat is bad. In fact, there are some kinds of fat you have to have for good health. A more accurate and helpful message would be: Eat more of some kinds of fats, less of others, and avoid one kind of fat whenever possible. Sure, it's a more complicated message, but it's also one that could help save your life.
A fat is any oily, organic compound that doesn't dissolve in water (just as oil floats on top of water) but does dissolve in oil or organic solvents. Chemically speaking, a fatty acid is made from a chain of carbon and hydrogen atoms — think of them as the building blocks of fat. (Later chapters on different kinds of fat go into this in a little more detail.)
The natural fats we eat fall into three basic categories:
1.Saturated fats. These fats are solid at room temperature; butter, lard, and suet are good examples.
2.Monounsaturated fats. Liquid at room temperature, monounsaturated fats include olive oil and many nut oils.
3.Polyunsaturated fats. Polyunsaturated fats are also liquid at room temperature. Canola oil, safflower oil, corn oil, and many other widely used vegetable cooking oils are polyunsaturated fats. The oil found in fatty fish is also polyunsaturated.
Polyunsaturated fatty acids fall into two main groups: omega-3 fatty acids (alpha-linolenic acid) and omega-6 fatty acids (linoleic acid). These two types of oils are essential: You must have some in your diet for good health. Just as you have to get your vitamins from the food you eat, the essential oils also must come from your diet.
THE UNNATURAL FAT
The American diet today is on the low side for good fats, mostly because we eat a lot of a completely unnatural fat: trans fatty acids, or trans fat for short. Also known as partially hydrogenated vegetable oils, trans fats are vegetable oils that have been chemically modified to be more saturated.
What makes trans fat so bad? Plenty. These unnatural fats raise the level of dangerous cholesterol in your blood, causing clogged arteries and heart disease. In fact, trans fats raise your cholesterol level about twice as much as saturated fat does. Even worse, trans fats are so widely used in processed foods, fried foods, and fast foods that they're hard to avoid. Just check the ingredients list on almost any prepared or baked good and you'll see partially hydrogenated vegetable oil somewhere on it.
The evidence against trans fat is now so convincing that the federal Food and Drug Agency (FDA) has announced plans to make food manufacturers list the amount of trans fats in their products on the food facts label. Chapter 5 explains the proposed labeling regulation and how it will help consumers avoid this deadly fat.
No discussion of dietary fat would be complete without a mention of cholesterol — even though this dreaded substance isn't really a fat at all. Cholesterol is a waxy chemical compound manufactured by your body. It's necessary for a variety of important functions, such as producing the hormones testosterone and estrogen and building cell membranes and brain and nerve tissue. Most medical authorities believe that high levels of cholesterol in the blood play a major role in causing clogged arteries and heart disease. High blood cholesterol, in turn, may be caused by eating animal foods such as meat, dairy products, and eggs, which contain cholesterol. Although this connection has yet to be fully proved, current dietary guidelines suggest that dietary cholesterol should be limited to no more than 300 milligrams a day. Chapter 4 discusses the dangers and benefits to your health of dietary cholesterol.
FATS ARE MIXTURES
It's important to remember that every fat is really a mixture of saturated, monounsaturated, and polyunsaturated fatty acids. One type of fatty acid is generally in the majority, though, and the fat is classified on that basis. Butter, for instance, is put into the saturated fat category because it contains mostly saturated fat. Butter is 81 percent fat. (The rest is mostly water.) One tablespoon (about 15 grams) contains 12.2 grams of fat, of which 7.6 grams are saturated fat, 3.6 grams are monounsaturated fat, and 0.5 grams are polyunsaturated fats. And because butter is a dairy product, it also contains 33 milligrams of cholesterol. So, a tablespoon of butter is more than half saturated fat, which is bad, but also has monounsaturated and polyunsaturated fats, which are good. And as Chapter 5 explains, think again before deciding margarine, which contains trans fats, is better for your health than butter.
It's also important to remember that every gram of fat, no matter what kind it is or where it comes from, contains 9 calories. For comparison, a gram of carbohydrates or protein contains 4 calories. Because a gram of fat contains 5 more calories than a gram of carbohydrates, in theory eating less fat means you eat fewer calories, which should in turn lead to weight loss. In practice, the opposite usually happens: To make up for the missing fat (and taste) in reduced-fat foods, manufacturers put in more sugar or other ingredients. The calories per serving don't decrease and you don't lose weight. In fact, you might gain, because you might start eating more calories. Why? You think that because the food has less fat, it's somehow more healthful and you can eat more of it. Also, fat in food plays an important role in satisfying your appetite and making you feel full. With less fat in your food, you don't feel as satisfied and you eat more. More calories, even when they're low fat, means you will gain more weight.
It's also important to remember that you need to have some fat in your diet for good health. Dietary fat is needed to carry vitamins A and E into your body, for example. You also need it for many other normal body functions.
Body fat isn't the same as dietary fat. Simply eating a diet relatively high in fat won't necessarily make you gain weight; likewise, eating a low-fat diet doesn't guarantee weight loss. In fact, there's no solid evidence linking a high-fat diet with obesity or a low-fat diet with thinness. Many people gain weight as they get older, for example, even as their intake of dietary fat remains the same. In the 1950s, most Americans got about 40 percent of their calories from fat. Today we get about 34 percent of our calories from fat on average, but we're fatter than ever — as mentioned, half of all American adults are now overweight.
And contrary to popular wisdom, it is possible to be too thin. Your body's fat deposits are used not only as a nutritional storehouse but also to cushion your organs and keep you warm, among other functions. If your fat deposits drop below normal levels, it can cause serious health problems, such as irregular menstruation and infertility in women.
RANKING THE FATS
Here's how the fats rank in terms of your health:
Polyunsaturated fats. Not only good but essential. The omega-3 and omega-6 fatty acids are essential, meaning you need them to live and have to get them from your diet. However, not all polyunsaturated oils are equal, and getting the right balance of omega-3s and omega-6s is crucial to good health.
Monounsaturated fat. Excellent. The best-known monounsaturated fat is olive oil, which has been shown to have a number of beneficial effects on health.
Saturated fat. Bad — or at least not as good as monounsaturated or polyunsaturated fat. A substantial body of medical research suggests — but doesn't prove — that a diet high in saturated fats may lead to high blood cholesterol, which in turn leads to an increased risk of heart disease. On the other hand, the link between saturated fat and heart disease isn't really as strong as many people think it is. The same is true for the link between a high-fat diet and some types of cancer, such as colon cancer, breast cancer, prostate cancer, and endometrial cancer. The evidence so far is suggestive but far from conclusive.
Trans fat. Deadly. These fats raise your blood cholesterol — and the more of them you eat, the higher your cholesterol will go. Avoid them.
Cholesterol. Not good, but perhaps not as bad as you think. Like saturated fats, diets high in cholesterol are associated with high blood cholesterol and an increased risk of heart disease and stroke. Eating less cholesterol doesn't generally do much to lower your blood cholesterol, however. There's also some solid evidence that diets too low in cholesterol can lead to a greater chance of stroke and possibly cancer.
HOW MUCH FAT SHOULD YOU EAT?
The dietary guidelines for Americans put out by the United States Department of Agriculture (USDA), the Food and Drug Administration (FDA, which is part of the Department of Health and Human Services), and the National Cholesterol Education Program (NCEP) from the National Institutes of Health all strongly recommend that you get no more than 30 percent of your daily calories from fat. Of those 30 percent, they further recommend that only 10 percent come from saturated fats. The guidelines also recommend that you take in no more than 300 milligrams a day of cholesterol.
Many other medical organizations strongly endorse the basic 30 percent rule. The American Heart Association gets a little more detailed in its dietary guidelines for healthy American adults:
Total fat intake should be no more than 30 percent of total calories.
Saturated fat intake should be 8 to 10 percent of total calories.
Polyunsaturated fat intake should be up to 10 percent of total calories.
Monounsaturated fat intake should make up 15 percent of total calories.
Cholesterol intake should be 300 milligrams or less per day.
Remember that the basic 30 percent — of — calories guideline applies to your average overall food intake over the course of a week or so. It doesn't apply to individual foods. In other words, it's perfectly okay to eat a normal portion of a food such as salmon, which gets 36 percent of its calories from fat, or nuts, which get anywhere from 75 to 90 percent of their calories from fat. The goal you're aiming for is an average of 30 percent of your total calories from fat from the total amount of the food you eat.
In practical terms, what does that work out to? Take a look at Table 1.1 to find out how many grams of fat and saturated fat are right for your average daily calorie level. When looking at this table, bear in mind that the average moderately active adult needs about 2,000 calories a day. If you're a lot more active, you need more calories; if you're inactive, you need fewer.
If you're overweight or need to limit your fat intake because you have high cholesterol or another medical concern, you might need to limit your fat intake to 25 percent of your daily calories or even less.
As mentioned, there is a problem with lowering your fat intake too much. A 1998 study by the Department of Agriculture showed that more than half of the women who reduce their fat intake to less than 30 percent of their daily calories don't get the recommended daily intake of vitamins A and E, folic acid, calcium, iron, and zinc. If you take in under 2,000 calories a day, and if 30 percent or fewer of those calories are from fat, you might be shortchanging yourself on your overall nutrition. If you're cutting calories and fat because you're dieting, be sure you do it in a way that gives you all the essential nutrients. If you normally take in less than 2,000 calories a day (because you have a petite build, for instance), you still need to be sure you're getting enough vitamins from your diet and from supplements if necessary.
So far, no medical or government body has come out with a specific recommendation for how much trans fat you should eat. There's an easy rule of thumb to follow, however: as little as possible, and certainly no more than 5 grams a day.
TRACKING YOUR FAT
How can you know if your diet matches the guidelines for fat? It's fairly easy to keep track of your intake of total fat, saturated fat, and cholesterol, because this information is found on the food facts label for packaged foods. For meals out and unlabeled foods, you can check any of the many fat-counter books. Unfortunately, until the labeling requirement for trans fats goes into effect, you'd be in the dark about the levels of these dangerous fats in processed foods. You can make an educated guess, however, by using the information in Chapter 5 and the "Trans Fat Content of Selected Foods" table at the back of this book. And you can use the information in Chapter 6 on the food label to estimate your fat intake.
FAT AND THE FOOD PYRAMID
To make the dietary guidelines for Americans easier to understand, the well-known food pyramid was introduced in 1992. At the base of the pyramid are six to eleven servings daily of grains: bread, cereal, rice, and pasta. Higher up are three to five servings daily from the vegetable group, and two to four servings from the fruit group. Above that are two to three servings daily from the meat, poultry, fish, beans, eggs, and nuts group and two to three servings daily from the dairy foods group. At the very tip of the pyramid are fats, oils, and sweets, with the advice to use them sparingly. This advice corresponds to the dietary guideline to get less than 30 percent of your daily calories from fat.
The dietary guidelines for Americans and the food pyramid are now very widely accepted. The overall advice is sound, but looking at the food pyramid makes a major flaw in the dietary guidelines very apparent. Combining meat, fish, poultry, eggs, beans, and nuts into one food group ignores the differing fat contents of these foods. Red meat, poultry, and eggs contain saturated fat and cholesterol, so the suggestion to limit these to a maximum of three servings a day makes some sense. Fish contains little or no cholesterol, however, but it does contain highly beneficial omega-3 oils that can help prevent heart disease. Nuts contain no cholesterol at all, but they are rich in beneficial oils.
Two recent studies by researchers at Harvard Medical School have looked carefully at how adhering to the dietary guidelines for Americans translates into better health. Their conclusions? For both men and women, following the guidelines made virtually no difference at all in their risk of developing a major health problem such as stroke, heart disease, or cancer.
Why aren't the dietary guidelines working as well as they should be? There are several possible reasons, according to the researchers. When a person's total fat intake is under 30 percent of calories, the diet may not contain enough beneficial unsaturated fats. Also, the carbohydrate base of the pyramid encourages people to eat more refined grains — and most processed baked goods are high not just in calories but in trans fats. And by combining red meat, fish, and nuts all in the same category, the guidelines actually discourage consumption of some healthy fats.
Does this mean that the dietary guidelines for fat should be ignored? No — but it does mean that you need to understand more about the fats in your diet to be sure you're getting the good ones and avoiding the bad ones. That's what the rest of this book explains.CHAPTER 2
THE BAD FATS
Saturated fat and cholesterol fall into the "bad" fats category, but that description is actually a little harsh. Saturated fat in moderation is perfectly healthy, as is cholesterol. In fact, cholesterol is extremely important for your overall health. These fats become bad only when you eat too much of them, especially if you eat them as part of an overall diet that's high in trans fats and low in good fats.
SATURATED FAT IN YOUR DIET
Saturated fats are "hard" fats — they're generally solid or semisolid at room temperature. Good examples are butter, tallow (beef fat), and lard. Some tropical oils, such as coconut oil, are liquid at room temperature but still very high in saturated fat.
All fats, however, are really mixtures of saturated and unsaturated fatty acids. Animal fats, such as lard and butter, are high in saturated fat, but they also contain high amounts of monounsaturated fat. In fact, lard has more monounsaturated fat than saturated fat per serving. Like all animal fats, lard contains some cholesterol (12 milligrams per 1-tablespoon serving), but it has far more monounsaturated fat than the supposedly more healthful vegetable oils such as soybean or corn.
Meat, poultry, eggs, fish, shellfish, and whole-milk dairy products, such as cheese and butter, contain saturated fat and cholesterol. Dishes made using these basic ingredients will contain saturated fat and cholesterol as well. Fruits, vegetables, and grains have no or very little saturated fat; nuts have some, but not a lot, and plenty of good fats that more than compensate.
Excerpted from The Good Fat, Bad Fat Counter by Sheila Buff. Copyright © 2002 Sheila Buff. Excerpted by permission of St. Martin's Press.
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