Is it Time to Ditch Low Fat Diets

Are we wrong to eat low fat? Gary Taubes, author of Good Calories, Bad Calories, and low carbers everywhere would say yes. Why do I invoke Mr. Taubes? Readers of the New York Times magazine may remember Taubes’ 2002 article, "What if it’s All Been a Big Fat Lie?" in which he explains how we came to embrace low-fat eating, and how the low-fat, high-carb diet trend has led to the obesity epidemic, insulin resistance and heart disease.

True, giving up bacon, butter, and ice cream only to fill up on low-fat but highly processed cookies, muffins and cakes, is hardly a recipe for good health, and certainly one likely to wreak havoc with our pancreases. No argument there.

Add to this the apparently disappointing outcome of long-term trials on low-fat diet and disease prevention, plus the results of a study of obese middle-aged Israeli workers, who lost more weight eating low carb than low fat, and you may wonder why we should eat low fat at all.

Low-Fat Trials and Tribulations

In particular, the Women’s Health Initiative Dietary Modification Trial, which followed close to 49,000 post-menopausal women for eight years, came up short. In this study, reported in February 2006, nearly 20,000 women were counseled to reduce their fat intake to 20 percent of calories, and to eat more fruits, vegetables and grains. The rest of the women—the control group—received some diet education materials but were not actively counseled to lower their intake of fat. At the end of the first year, the low-fat dieters cut their fat intake to 24 percent of calories, while the other group’s intake was 37 percent. By the end of the study, the low-fat dieters were getting 29 percent of their calories from fat, and the other women about 35 percent. At the end of the eight-year period, researchers concluded that eating low fat failed to reduced the risk of cancer and cardiovascular disease.

Critics of the study argued that the women didn’t restrict their fat intake sufficiently, and that there were no guidelines about eating the "right" kinds of fat. Even so, the headlines were clear: low-fat diets failed to cut the risk of disease.

Does Eating Low Fat Do Any Good At All?

Despite the headlines, there were some encouraging trends in the Women’s Health Study that almost went unnoticed. The women who started with the highest intake of fat and who reduced it the most, cut their risk of breast cancer by 15-20 percent. The other women in the low-fat diet group reduced their risk by 9 percent (though this was deemed statistically insignificant). Plus, the women on the low-fat diet reduced their LDL (bad) cholesterol slightly. In general, those who cut their intake of saturated fat and trans fats the most while increasing their intake of fruits and vegetables, had better results than their peers.

What has since emerged from this study, as reported in October 2007, is that women following the low-fat diet did manage to reduce their risk of ovarian cancer. Again, those who started with the highest intake of fat reduced their risk the most.

Can a Low-Fat Diet Be Heart Healthy?

Yes, but not in a vacuum. Cutting total fat intake must also be in line with cutting overall calories (yes, that's the catch), and increasing physical activity. Living this way has helped many people lose weight and improve their lipid profiles.

But one thing to bear in mind: even at nine calories per gram (compared with four calories per gram of carbohydrate or protein), all fats are not created equal. Instead of cutting fat indiscriminately, it pays to replace saturated fats and trans fats with unsaturated fats, especially those rich in omega-3 fatty acids. Omega-3 fatty acids are thought to protect against heart disease, inflammation, certain types of cancer, diabetes, Alzheimer’s disease, and macular degeneration. We should budget our fat calories wisely.

Interestingly, a study published in the October 2007 Journal of the American Dietetic Association declared the very-low-fat Ornish Diet to be best for heart health. Researchers from the University of Massachusetts Medical School rated eight popular diet plans, choosing one seven-day menu plan from each The menus were the ranked according to seven dietary components most strongly linked to reducing heart-disease risk: fruits, vegetables, nuts and soy, ratio of white to red meat, fiber, trans fat, and ratio of polyunsaturated fats to saturated fats. Each component was worth 10 points.

Out of a possible 70 points: the Ornish Diet came out on top with 64.6 points, followed by Weight Watchers high-carb diet with 57.2 points. The bottom two plans, much to the consternation of cardiologist Arthur Agatston, were the South Beach Diet Phase 3 with 45.6 points, and the Atkins Diet with 42.3 points.

Saturated Fats and Trans Fats

Although there are many who believe the case against saturated fats is overblown and unproven, there is some evidence that high intakes of saturated fat can have adverse effects on our arteries only hours after consuming a high-fat meal. Another study suggested that a build up of saturated fat in heart cells worsened the severity of a heart attack and increased the risk of death.

While the role of saturated fat remains somewhat controversial—many argue that saturated fat from plant sources is metabolized differently to animal fats, and doesn’t raise blood cholesterol—almost all agree that artificial trans fats should be avoided. Once the answer to replacing so-called artery-clogging animal fats, hydrogenated vegetable oils were seen as a boon to the food industry, from increasing the shelf life of foods, to providing texture and mouth-feel. But trans fats not only raise levels of bad cholesterol, they also lower levels of good cholesterol. Trans fats are fast disappearing from menus all across the United States. But guess what’s replacing them? Saturated fats, albeit from plant sources.

Eat Low Fat if You Want

Given all this, it’s not clear to me that I should be jettisoning a low-fat diet at all. The biggest downside for some is that it can leave them feeling hungry. Fat helps us feel full, but complex carbohydrates can also help us feel full. A low-fat diet might not be for everyone, but if it works for you, and your doctor approves, there seems no compelling reason to ditch it. But remember, if you choose to eat low fat, don't replace those fat calories with simple (refined) carbohydrates.

Instead:

• Cut your overall intake of fat, and within that, choose unsaturated fats instead of saturated ones.
• At the same time, reduce your intake of sugars and refined carbohydrates, principally by eating fewer processed foods. Grab an apple, not a coffee-shop reduced fat muffin.
• Eat little and often, and stay hydrated. Sometimes we mistake thirst for hunger.
• Get moving, even if it means only a brisk walk around the block a couple of times a day.

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