The statistics tell a scary story. More than one-third of U.S. adults—close to 80 million people, according to the Centers for Disease Control and Prevention—are obese, and as Americans’ waistlines continue to grow so do rates for chronic health conditions such as Type 2 diabetes and cardiovascular disease.

But does the path to weight loss and better health lie in eating like our hunter-gatherer ancestors, eschewing grains, dairy products and the other foods of the modern agricultural era in favor of protein, nonstarchy vegetables and healthy fats such as coconut oil?

That’s what advocates of a paleo diet say. Government health experts in Washington, though, seem to disagree. The latest dietary guidelines from the U.S. Agriculture Department encourage Americans to consume whole grains and dairy products on a daily basis, and to avoid foods high in fat.

Arguing in favor of a paleo diet is Kellyann Petrucci, a naturopathic physician, certified nutritional consultant and clinical director of Birmingham Wellness Center in Birmingham, Mich. Making the case against it is Marion Nestle, a professor of nutrition, food studies and public health at New York University and author of “What to Eat.”

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