The Paleo Diet Myth

Why living like a caveman won’t boost your metabolism

Back in the early 1980s, I began investigating what humans ate in prehistoric times.

I believed then (and now) in a traditional diet devoid of the processed and packaged foods that are so pervasive today.

I tried to explain to my colleagues at the National Institutes of Health that the type of diet our ancient ancestors ate—fruits, vegetables, nuts, seeds, meat, and fish—would be ideal for a study on how to prevent cancer and chronic diseases. (Conditions that are much more prevalent today than they were back then.)

Unfortunately, with big pharma’s so-called scientific advisors insisting on incorporating synthetic “supplement pills” into the study, we couldn’t make it work.

But I did receive some phone calls at home from a private clinical specialist (with absolutely no background or training in anthropology, nutrition, or metabolism) about my idea. And the next thing I knew, he coauthored the first “pop” book on the paleolithic diet, or paleo for short.

Now, paleo diets are an international craze. But like most fads, they’re being advertised as much more than they actually are. Instead of simply promoting healthy eating plans, “nutritionists” now tout paleo diets as a way to lose weight by revving up your metabolism.1

But that’s just another big, fat myth. And here’s why…

Our ancestors didn’t have faster metabolisms

Over the years, I’ve unveiled numerous myths about mainstream medical recommendations regarding diet, metabolism, and nutrition. And the paleo diet is no different.

Metabolic studies in different populations demonstrate that the average number of calories you burn each day stays fairly consistent, regardless of your activity levels.

So the theory that the paleo diet helped our ancestors be more active, ramp up their metabolism, and expend more calories is a bold-faced lie.

Anthropologists have shown that in traditional paleo hunting-and-gathering societies, there’s actually a lot of leisure time. After food sources are found in the wild, people have plenty of opportunity to engage in arts, crafts, and social interactions.

In fact, anthropologists discovered that the amount of physical labor needed to survive actually increases when people settle down in one place to grow crops.

The Hadza people of East Africa are a modern-day example of how our paleo ancestors lived. The Hadza build simple mud huts and hunt with tools made by hand. So you might assume that they’re laboring 24/7 in a daily struggle for survival, and are continually burning massive amounts of calories.

And yet, modern metabolic studies show that the typical Hadza burns no more calories than a modern, sedentary American.

How can this be? Well, much of it has to do with how diet and exercise affect basic human metabolism.

Why exercise won’t jump-start your metabolism

Study after study shows the typical adult 50 and over burns about 2,500 calories per day, depending primarily on body size. Bigger bodies burn more calories because they have more cells and tissues consuming calories.

So, based on your size, you have a daily calorie baseline. And despite all of the hype you hear, you can’t boost that baseline by doing extra “workouts.” (Yet another reason excessive exercise is nonsensical, as I always warn.)

That’s because when you exercise more, your body simply reduces the amount of calories it burns performing other functions—like producing hormones or immune cells.

This response keeps your metabolism constant. In effect, your body “traditionally” needs to conserve energy when it can, and sees excess exercise (or as I call it, excess-ercise) as wasted calories.

So essentially, too much exercise actually starves your metabolism.

I recommend moderate amounts of exercise—2.5 hours per week of walking, swimming, gardening, housework, etc. This amount of physical activity is in line with what our ancestors would have gotten when hunting and gathering—and it will help your body function optimally, without spending hours and hours in a dark, dank gym.

Eating like a caveman won’t rev up your metabolism either

No matter what the so-called paleo “experts” say, there’s no such thing as a diet that can increase your metabolism.

In fact, research shows that extreme low-calorie diets actually lower your metabolism, as an evolutionary signal to keep you from starving to death. So when you eat less, your body burns fewer calories—creating a net-zero effect.

The bottom line is that you can eat—and exercise—like a caveman, but “paleolithic prescriptions” from pop doctors aren’t going to revamp your metabolism.

I’m all for “tradition” (and I’m not just fiddling on the roof), but we really need to understand what the traditional (“paleo”) human diet, metabolism, and nutrition is really about.

That said, the paleo diet isn’t a bad eating plan. It’s rich in fruits and vegetables, protein, and healthy fats. And it’s low in sugar and simple carbs. It’s the type of sensible diet that can help you maintain a healthy weight.

But it’s not the “miracle diet” the hypesters tout.