THE BLOG
09/03/2014 05:18 pm ET Updated Nov 03, 2014

Low-Carb Beats 'Low-Fat'? Take a Closer Look

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It's hard to miss the new Tulane University study which finds that -- contrary to decades-old warnings about the risks of a high-fat diet -- eating more fat can help you lose weight and lower your risk of cardiovascular disease.

So is it time to binge on burgers, bacon, and cheese? Not so fast. The study's flaws reveal that what seems like a heavy blow to conventional wisdom about nutrition is in fact just another red herring pointing consumers in a deadly direction.

The study's biggest downfall is its definition of a "low-fat" diet as one in which no more than 30 percent of calories consumed daily come from fat -- with no more than seven percent of calories from saturated fat. What might such a diet look like?

Someone following this definition could consume a McDonald's fruit-and-yogurt parfait with granola and a strawberry banana smoothie for breakfast, a grilled-chicken ranch BLT sandwich and a large Coke for lunch, and a double cheeseburger with a large Coke for dinner. In fact, one could consume nearly double the total amount of fat in all of these foods and still stay within what this study calls a "low-fat" diet.

Only in America could this way of eating be considered low-fat. This study's authors allowed their research to be skewed by our ultra-high-fat culture in which diets full of fast food, meat, dairy, and processed junk are the norm. The participants -- all of whom were obese -- were put on a "low-fat" diet that was hardly different from the one they followed before the study began. In setting their study up this way, the researchers created a meaningless comparison between two slightly modified Standard American Diets, neither of which is healthful -- and neither of which is actually low in fat.

On the other hand, a true low-fat diet -- one composed entirely of high-fiber, plant-based foods -- has demonstrated health benefits far beyond what either group in this study was able to achieve. These diets have been clinically proven time and again to boost metabolism, lower blood pressure, and stabilize blood sugar, among other positive effects.

For example, in 2005, the Physicians Committee compared a low-fat, vegan diet to a control diet based on National Cholesterol Education Program guidelines -- the very same guidelines used for the supposedly "low-fat" group in the Tulane study. In both studies participants were given no calorie limits and were asked not to change their exercise routines. My colleagues and I found that compared with the control group, those on a truly low-fat diet lost considerably more weight.

Another important difference between these studies -- and a second flaw of the latest one -- is that our study participants on the low-fat diet considerably increased the amount of dietary fiber they consumed over the course of the trial. A significant body of evidence also supports the notion that fiber -- found only in plant-based foods like fruits, vegetables, beans, and whole grains -- plays a key role not only in weight loss but also in the prevention of a range of chronic diseases, from cancer to heart disease. Those following a "low-fat" diet in the Tulane study consumed very little fiber, which also helps to explain why they didn't lose more weight or further decrease their heart disease risk.

We also know that weight loss and other health benefits almost always occur when research participants are counseled on nutrition and healthful eating, regardless of what diet they are supposed to be following. In the low-carb/low-fat study, both groups significantly reduced their waist circumference (with no major difference between the groups), which in some cases can be a better marker of overall health and disease risk than weight loss alone or even BMI.

Finally, both the "low-fat" and low-carb groups in the Tulane study actually reduced their fat intake, so this refutes the popular claim that eating more fat leads to weight loss.

The take-home message? Don't be fooled by the promises of riding your way to good health and a slim figure on a river of ice cream and butter. Stick with what scientists have known for decades: A low-fat, plant-based diet is decidedly best for our health.