En español l Low fat, low sugar. High fat, low carb. High carb, plant-based. Mediterranean. Atkins. Ornish.
At some point in the past 12 months, at least one study has appeared in a well-respected, peer-reviewed medical journal touting the health benefits of each of these diets. A study in the journal The Lancet Oncology found that the Ornish diet — a strict low-fat regimen that allows no more than 10 percent of calories from fat — not only reverses heart disease, but it also lengthens our telomeres, the bits of DNA on the ends of chromosomes, in effect increasing longevity. Then again, a study in the New England Journal of Medicine found that a relatively high-fat Mediterranean diet — with its emphasis on fatty fish, nuts and olive oil — prevents heart disease and stroke while cutting your risk of diabetes, too. But wait! Adults who eat a mostly plant-based diet live significantly longer than meat eaters, says JAMA Internal Medicine.
This conflicting dietary advice from the world of medical science is made even more complicated by the diet books, documentaries and news reports recently flung into the nutritional universe. (Meat and butter are good for you! Sugar will kill you!) Is it any wonder, then, that so many of us have decided to say the heck with it — we may as well have our filet mignon and foie gras while we're still alive to enjoy it?
Well, not so fast. It's true that the science is confusing, says Walter Willett, M.D., noted nutritionist and chair of the Department of Nutrition at the Harvard School of Public Health. But it's also true that we are in the throes of an obesity crisis so pervasive that 1 in every 4 health care dollars are spent combating the resulting side effects of heart disease, diabetes, high blood pressure and high cholesterol.
And the very nature of scientific discovery, with nutrition research a subset of that, is that findings build on one another, adding to our total understanding of what constitutes a healthy diet.
This, then, is what most of the experts agree is true — at press time, anyway.
Eating fat doesn't make you fat
"The whole idea that reducing fat intake is the most important thing you can do was never supported by any good evidence," says Willett. Nonetheless, that line of thinking drove national nutritional policy for decades and may have contributed to our current health problems, as everyone rushed to replace fat with carbohydrates, says Gary Taubes, whose international best-seller Good Calories, Bad Calories makes just this claim.
Some fats are better than others
Trans fats, sometimes listed on food labels as "partially hydrogenated oils," are artificially manipulated fats that food producers use to enhance the shelf life of processed foods. Research has shown that trans fats raise "bad" LDL cholesterol levels, leading to heart disease. So avoid trans fats at all costs. (The FDA is working to ban trans fats, and many European countries already have.) Saturated fats — found in red meat, cheese and butter — are better than trans fats, but recent research has found that a diet high in saturated fat is dangerous for heart health, Willett says. Better choices? Olive oil, nuts and legumes.
Next page: Not all calories are created equal. »