| |
Newsweek, Nov. 13, 2006
Woo-hoo! Bring out the bacon and eggs and let’s get this party started!
Well, not exactly.
Having seen what a powerful difference changes in diet and lifestyle can make, I’m concerned that this new study may cause some people to believe that steak and brie are actually good for your heart. I’d love to be able to tell you that they are, but they aren’t. Hey, don’t shoot the messenger—it’s fine to indulge yourself sometimes, just don’t kid yourself.
I debated Dr. Robert Atkins on many occasions before he died two years ago. I was usually portrayed as the “low fat” physician, and he was the “low carb” doctor. However, that’s the wrong distinction—it’s not low fat versus low carbs. As I have consistently described, an optimal diet is low in “bad fats” such as saturated fat and trans fatty acids and low in “bad carbs” (refined carbohydrates) such as sugar and other concentrated sweeteners, white flour, and white rice. A healthful diet includes “good fats” and “good carbs.” Good fats such as the omega-3 fatty acids are contained in fish oil and in some nuts and seeds, including walnuts, flax seeds, and canola oil (but not olive oil). Good carbs are found in unrefined, whole foods such as fruits, vegetables, whole grains (whole wheat flour and brown rice), and legumes. Besides being low in harmful substances, these good fats and good carbs have literally thousands of protective nutrients that help protect against coronary heart disease as well as many of the most common cancers such as prostate cancer, breast cancer, and colon cancer. These include phytochemicals, bioflavonoids, carotenoids, retinols, isoflavones, genistein, lycopene, and so on. These protective nutrients also enhance immune function and help to slow the aging process.
Why are too many refined carbohydrates bad for you? The fiber and bran found in unrefined “good carbs” are removed when sugar cane is refined into sugar, or whole wheat flour is refined into white flour, or brown rice is refined into white rice. Because of this, you can consume large amounts of these “bad carbs” without getting full, since fiber and bran are very filling. Also, fiber and bran cause your food to be absorbed more slowly from your stomach and intestines into your bloodstream. When the fiber and bran are removed, your food gets absorbed very quickly, causing your blood sugar to spike to high levels. This, in turn, stimulates your pancreas to make more insulin. Insulin accelerates the conversion of calories into triglycerides (fat). Over time, repeated insulin surges may lead to insulin resistance in some people which, in turn, may promote diabetes.
If you pull a pendulum to one side and let it go, it doesn’t stop in the middle; it goes an equal distance to the other side. Likewise, when your blood sugar spikes and your body makes insulin to bring it back down, it may go down below where it started. These low blood sugar levels cause you to feel tired and to have a craving for more refined carbohydrates in a vicious cycle. Thus, bad carbs give you a double-whammy: you can eat too many calories without getting full, and you’re more likely to convert these calories into fat.
However, unrefined carbohydrates (“good carbs”) act very differently. Because they are high in fiber, they fill you up before you get too many calories. If you eat an apple, for example, you’re likely to get full before you consume too many calories. Also, the fiber in good carbs slows the absorption of food into your blood, so you don’t have wide swings in your blood sugar. This gives you a more constant feeling of energy throughout the day and reduces carbohydrate cravings. In our research, as well as in other studies, many people who were eating a diet low in fat and bad carbs and high in good carbs become more insulin sensitive rather than insulin resistant. Those with diabetes are often able to reduce or even discontinue insulin (under their doctor’s supervision, of course) yet maintain normal blood sugar levels. This significantly reduces the complications of diabetes, including coronary heart disease as well as reduced eye, nerve, and kidney damage.
OK, let’s get back to this new study from the Harvard School of Public Health. It concluded, “Our findings suggest that diets lower in carbohydrates and higher in protein and fat are not associated with increased risk of coronary heart disease in women.”
However, this study had significant problems. Studies are designed to answer questions, called hypotheses. Is drug X better than drug Y? Does a low-carbohydrate diet increase the risk of developing coronary heart disease? Not surprisingly, the most important factor in any study is to have accurate data. In the Harvard study, women were asked to complete a food frequency questionnaire that asked them to write down how much and how often, on average, during the previous year they had consumed different foods. We have used these questionnaires in some of our studies, so I know how challenging it can be to obtain accurate data with them. I don’t know about you, but I have a hard enough time remembering exactly what I ate yesterday.
Although most studies have shown that what you eat affects your cholesterol level, the Harvard researchers reported in their new study that “the low-carbohydrate-diet score was not associated with total cholesterol, HDL cholesterol, or LDL cholesterol levels.” This is what you would expect to find if the data from the food frequency questionnaires were not very valid. And if the low-carbohydrate-diet score was not correlated with blood cholesterol levels, when it should have been, it’s not surprising that the low-carbohydrate-diet score was not correlated with the risk of coronary heart disease either.
Although the summary of the researchers’ results said, “Our findings suggest that diets lower in carbohydrates and higher in protein and fat are not associated with increased risk of coronary heart disease in women,” a closer analysis of their data actually challenges that conclusion. Table 4 of their study examined the relative risk of developing coronary heart disease based on the intake of different nutrients. What the researchers found was the following:
- Total fat intake significantly increased the risk of developing coronary heart disease
-
Animal fat intake significantly increased the risk of developing coronary heart disease
-
Vegetable protein intake significantly decreased the risk of developing coronary heart disease
-
Vegetable fat intake significantly decreased the risk of developing coronary heart disease (although not clear if this is because they were eating less animal fat or because the vegetable fat was protective)
-
Intake of refined carbohydrates (“bad carbs”) significantly increased the risk of developing coronary heart disease
Low-carb diets like the Atkins diet are often higher in animal fat and lower in vegetable protein and vegetable fat. If people go on these diets believing that they have no effect on their risk of developing heart disease, they may be mistaken.
A more helpful message from this study is that an optimal diet is low in total fat, low in animal fat (saturated fat), low in trans fatty acids, and low in refined carbohydrates (“bad carbs”). What you include in your diet is as important as what you exclude, so eat more good carbs such as fruits, vegetables, whole grains, legumes, and soy products. In this study, those who ate this way were able to reduce their risk of developing coronary heart disease by up to 30 percent. Although people tend to highlight the differences among different diets, there is actually a growing convergence and consensus that this approach constitutes an optimal way of eating.
Energy balance is also important. You lose weight when you burn more calories than you consume. Of course, exercise burns calories. You can consume fewer calories by eating less food, but it’s hard to sustain, because most people don’t like feeling hungry and deprived for very long. You can also eat fewer calories by changing the type of food as well as the amount—less fat and fewer bad carbs. Fat has 9 calories per gram, but protein and carbohydrates have only 4 calories per gram, so when you eat less fat, you consume fewer calories without having to eat less food. As described above, it’s easy to eat too many bad carbs without getting full, whereas good carbs tend to fill you up before you get too many calories.
It’s not all or nothing. You have a spectrum of choices. To the degree you eat less of the bad carbs and bad fats and more of the good carbs and enough of the good fats, you’re likely to look better, feel better, lose weight, and gain health.
© 2006 MSNBC.com
|
