How Bad for You Is the Paleo Diet, Really?


Could the Paleo diet—often touted by CrossFitters and super fit celebs like Jessica Biel and Megan Fox—be really bad for your health? That’s the buzz this week surrounding new research published in the journal Nutrition and Diabetes.

For the study, scientists at the University of Melbourne divided their subjects—overweight, prediabietic mice—into two groups: One group was put on a low-carb, high-fat (LCHF) diet, while the other was fed standard rodent fare.

At the end of nine weeks, the LCHF group had gained more weight, developed poorer glucose tolerance, and higher insulin levels. In fact, the mice in that group actually gained 15% of their body weight. “That’s extreme weight gain,” lead author Professor Sof Andrikopoulos said in a press release. "This level of weight gain will increase blood pressure and increase your risk of anxiety and depression and may cause bone issues and arthritis.”

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Andrikopoulos went on to liken the rodents’ LCHF diet to caveman-style eating—and ever since, the media has been spinning dire warnings about the Paleo diet making people fat and sick.

But let’s back up for a minute. First of all, the study was done on mice and we, of course, are not mice. Secondly, the study text doesn't mention the word “Paleo” at all. And third, the LCHF diet in the study was not just high-fat but very high-fat—81% of total calories came from fat, more than half of which was saturated.

Granted, Paleo is a type of low-carb, higher-fat diet. But people who follow it don’t necessarily load up on lard. Human beings who eat in the spirit of our cave-dwelling ancestors can choose chicken and lean cuts of beef over bacon and pork belly. A more accurate depiction of Paleo is a nutritional regimen centered around pasture-raised meat, fresh fruits and veggies, eggs, nuts, seeds, and oils.

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“To even suggest that a single mouse study can be extrapolated to show causality in humans is just bad science,” says Loren Cordain, PhD, a professor emeritus at Colorado State University and author of The Paleo Diet. "The study totally lacks the criteria and objectivity by which most of the scientific, nutritional community uses to establish cause and effect between diet and disease."

Cordain points out that much of the popular press coverage of this new research “ignores the most recent human meta-analysis showing the health and weight loss efficacy of randomized controlled trials evaluating contemporary Paleo diets.”

The review he’s referring to was published last year in The American Journal of Clinical Nutrition. The researchers analyzed four studies and concluded that, at least in the short-term, Paleo diets reduced waist circumference, triglycerides, blood pressure, and fasting blood sugar.

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But until we have longer-term human studies, the smartest move may be following the diet that makes you feel good—whether that's Paleo, Mediterranean, vegetarian, veggan, or simply eating clean.