Is a Low-Carb Diet a Genuine Remedy for Obesity?

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David Bebber/Reuters

The outrageously high rates of childhood and adult obesity and diabetes in the U.S. may suggest that the U.S. Dietary Guidelines (DG) are not working. After all, these guidelines are meant to protect our health. So how did we find ourselves in this predicament?

As a longtime researcher, contributor to food and health policy, and Cornell University professor emeritus, I offer the following interpretation. The current DG recommendations for healthy levels of fat, protein and carbohydrate consumption will not optimize health. In addition, the scientific research supporting the dietary lifestyle that will optimize health is mysteriously missing from the 700-plus page recommendations.

In a Newsweek article on June 11, 2015, “Food Guidelines Are Broken. Why Aren’t They Being Fixed?” Dr. Jeff Volek asserts that the science being used to justify low-fat dietary recommendations in the DG reports is outdated, and more comprehensive science must be used to create the guidelines.

He also states that most Americans eating a low-fat diet will cut down on full-fat animal products while simultaneously increasing intake of sugar and processed starches. As a result, diabetes and obesity will continue to plague our nation.

Although there is some truth in his comments, his understanding of low-carb diets and scientific research is fundamentally different from mine. I agree that a more comprehensive evaluation of the evidence be considered, but this means including the evidence on the health benefits of a whole-food, plant-based (WFPB) diet, which is omitted from this report.

It should be noted that a low-carb diet often means, by definition, a diet very high in protein and fat (from meat, dairy and eggs). A low-carb, high-protein diet may cause weight reduction initially, but in the long run it is overwhelmingly dangerous and not in our society’s best interest.

The biggest issue is that low-carb diets severely limit the consumption of plant-based whole foods, which are the main foods reversing disease and creating health benefits. A diet of these foods contains about 10 percent fat, 10 percent protein and 80 percent complex carbohydrates. This diet has all the protein we need, the right amount of fat and a rich supply of antioxidants, vitamins, minerals and complex carbohydrates.

Now let’s focus on fat and note that the Standard American Diet has mainly held steady at about 35 to 37 percent fat for decades. Volek and his colleagues incorrectly claim that we experimented with a so-called 30 percent “low-fat” diet during the last few decades, only to see an increase in the prevalence of obesity. This is flat-out wrong.

First off, how is 30 percent fat considered “low-fat” when those eating a diet of plant-based whole foods consume around 10 percent fat? And second, never did the average dietary fat go as low as 30 percent, and even if it did, it would be a trivial change that cannot possibly account for the childhood obesity epidemic. This is similar to comparing someone who smokes four packs of cigarettes a day with someone who smokes three.

And what does “high-protein” mean? For decades, 10 percent dietary calories as protein (RDA, the recommended allowance) has been considered sufficient (if not ideal) for human health. This level of protein is easily provided by a WFPB diet.

But for more than 10 years, the DG Advisory Committee has continued to recommend that a diet with up to 35 percent dietary protein maintains health and prevents heart disease, cancer and other Western diseases. A WFPB diet easily has 10 percent protein—and more, if legumes and leafy greens are emphasized, which enhance health.

On the contrary, if dietary protein is increased by animal source foods, chronic degenerative diseases are greatly increased. Consider the long-term impact of the Atkins (low-carb) diet with regard to disease and you could find that short-term weight loss by overeating meat may be a sad trade-off for real long-term health.  

Unlike high-protein, high-fat diets, a WFPB dietary lifestyle provides a remarkably broad ability to resolve illnesses and diagnosed diseases. Heart disease, type 2 diabetes, obesity and many autoimmune diseases also can be resolved for most people remarkably quickly.

If the DG Advisory Committee and other authorities acknowledged this missing evidence and promoted a WFPB diet, our health care costs in the U.S. could be cut 50 to 75 percent, and rates of preventable, diet-related diseases would plummet. There is no evidence that low-carb diets high in animal protein and fat can achieve this effect.

Low-carb advocates are in denial that a WFPB diet could be a more viable way for Americans to lose weight and live without preventable diseases in the long and short term. However, like the meat, poultry and dairy industries, low-carb supporters want you to ignore this possibility and just eat more meat.

If low-carb advocates would stick to the issue of the over-consumption of refined carbohydrates, we could find an area of agreement. But it is clear to me that when they promote a low-carb diet, they are cleverly choosing words mixed with a little truth to push yet another diet that continues to reinforce unhealthy habits.

T. Colin Campbell is professor emeritus of nutritional biochemistry at Cornell University, and board president of the T. Colin Campbell Center for Nutrition Studies.