A recently released study on human energy expenditure (“Hunter-Gatherer Energetics and Human Obesity,” Herman Pontzer et al.) has garnered some attention in the media. The reason for all the attention? The study debunks a commonly held belief that our obesity epidemic is in large part due to our decreased physical activity.

Up until now, we’ve all heard one of the main reasons we are fat, and getting fatter, is we move far less than our ancestors (namely the hunter-gatherers). Images of animal-skinned Neanderthals chasing wild game across miles, picking at the last berries on a bush, and scratching mere mouthfuls from the dirt pervade our minds. When compared to our cushy lifestyles of cube-farm offices, drive-thrus, and delivery pizza (don’t forget Roomba, clothes dryers, and telecommuting), we look downright slothful. When’s the last time you did more than tear open some plastic for a big ol’ piece of beef?

I too was bought into the notion of decreased, daily caloric expenditure as a primary contributor to our gluttonous predicament. I loved to compare the “cost” of food in the way-back to today by how many calories you had to spend to acquire it. It made perfect sense to me. Back in the day you probably had to expend a few hundred calories to get maybe 50 — or so I thought.

Based on Pontzer’s research, we all need to step back and re-evaluate our self-flagellating model of laziness. Those purposeful, insane workouts meant to compensate for our post-Agrarian lifestyles ain’t gonna help that much. According to Pontzer and his team, when comparing Western culture to Hunter-Gatherer culture, we burn about the same calories. Even more fun to notice is Westerners actually burn more calories if you look at the total (in the study, they compensated for fat/lean body mass). That’s right; factor in our girth and we burn more. More. Hunter-gatherer women in the study averaged about 1,877 calories a day. Western women? Try 2,347. Hunter-gatherer men averaged around 2,649, while Western men racked up 3,053 calories a day. Physical activity calories burned across the two groups was about the same, regardless of culture/lifestyle.

Go figure.

So what’s the so what of all this scientific-mumbo-jumbo? It means we are all eating too dang much. And I have to say, I actually felt vindicated when I read numbers like 1,800 and 2,600. My tirades against 1,800 calorie mega-burgers (for lunch) are justified.

And yes, you could argue the types of foods we eat are impacting hormonal systems, firing off genes heretofore dormant, pesticides, herbicides, and plastics are jacking us up.

But I’m telling ya, the easiest answer here is we eat too much. Mocha-choca-lattes as “drinks,” burgers that could serve a family of four, “personal” pizzas that used to be called “medium,” and the eradication of “small” from most menus are among the overindulgent proof.

And before a few of you have a freak out, I’m not proposing tossing in the gym towel. Exercise, both moderate and vigorous, have numerous — NUMEROUS — health benefits. Just don’t go expecting the scale to start zinging down to pre-pubescent weights from a mere 60 minutes a week.

Wanna test me? Track everything you eat for a week. I mean everything. If it crosses your lips, write it down. Weight it. Measure it. Add it all up. See how many calories you are taking in. Bet you’d have to exercise vigorously, non-stop, for a decade to undo the damage. Betcha.

• NSCA certified personal trainer Shannon Sorrels has a bachelor’s degree in chemistry and an MBA. Her Ahwatukee-based company, Physix LLC, works with Valley individuals and groups to improve their overall fitness. Reach her at (480) 528-5660 or visit www.azphysix.com.

(3) comments


Ok, so I've seen references to this study floating all around the internet and the conclusions of the researchers are so flawed its a joke. The hunter gatherer men in the study AVERAGE 5'2" and weigh on average around 110 pounds. Their basal metabolic rate is around 1300 calories a day. So the fact that these men are consuming 2700 calories a day means they are consuming an enormous amount of food day in day out. They are eating almost double their BMR.

Think about it. A 6'2" male who weighs 185 pounds might have a BMR of 1950 calories. So for him to be eating PROPORTIONALLY THE SAME as the Hadza tribesmen, he would need to consume almost 4000 calories a day.

I can GUARANTEE that a typical even fit, gym going male who works a desk job and lifts / does cardio an hour every single day will get enormously fat if he ate 4000 calories a day, day in, day out.

To put it in perspective, walking an hour burns a couple hundred extra calories, running an hour burns maybe 500-700 depending on intensity. If you hold constant HEIGHT WEGHT-PROPORTIONAL CALORIE CONSUMPTION, THEN THE ONLY WAY TO EAT DOUBLE YOUR BMR EVERY DAY IS TO ENGAGE IN DRAMATICALLY MORE PHYSICAL ACTIVITY THAN WE TYPICALLY GET IN SEDENTARY, DESK JOB WESTERN WORLD.

So, the equation our bodies were calibrated to in hunter gatherer times was : eat double your BMR every day in calories BECAUSE YOU WILL WALK , JOG, AND RUN FOR 4-8 HOURS A DAY TO SUPPORT YOURSELF.

So the conclusions of the researchers are EXACTLY WRONG. We do get much less physical activity on average, and if our bodies digestive system developed to be able to comfortably consume twice our BMR in calories, how do we know that our desire to eat 4000 calories a day isn't the CONSTANT in our genetic


(Continued from below). Makeup.

I suspect that the RIGHT CONCLUSION - that the Hadza get up, walk , jog and run 4-8 hours a day and eat twice their BMR to support this activity is a balanced equation that means our natural, primitive selfs want to move an awful lot, and eat a lot. I don't think you can have one and not the other. We are programmed to consume and we will do so whether we are physically active enough to match it.

So either we fight our genetic programming and amidst the abundance around us in the west, we constantly do the unnatural thing (resist eating ) instead of doing the aural thing to keep. Everything in balance -- MOVE AROUND MORE.

Again, it is just plain embarrasing hoe wrong the published conclusions of this study were.


Hi "Johnjohnjohn,"

I'm thrilled you felt strongly enough about the article to post a comment. Love it! :-)

I've read your response several times trying to completely understand your points in reference to the cited study. Here's my highlights of what I think you aret saying:

-- Based on body size, westerners have higher BMRs than the hunter-gatherers in the study (I agree)
-- HGs get lots more physical activity each day than their western counterparts (agreed)
-- If westerners ate 4,000 calories per day and didn't get in additional physical activity, they'd gain a lot of weight (agreed, and it's around us)
-- We are "programmed" to want to move a lot and resultingly eat a lot to maintain weight/body balanace (this is where I think we diverge - assuming I summarized your thought correctly)

In the study, the researchers tried to level the playing field (because Westerners ARE bigger than the HGs) by using Fat-Free-Mass (FFM). They noted that HGs did expend more calories via physical activity and their BMR was lower (controlling for FFM). Westerners had higher BMRs and lower PA bringing the Total Energy Expenditure (TEE) in line with each other (statstically speaking).

The point the paper is trying to toss out as a theory, based on data thus far, is that humans burn roughly a range of calories (based on body size) and have for a long time. Given that range and a look at our ever increasing waist lines, that leaves food (intake) as the culprit.

I know from experience that many, MANY, folks are taking in 300-3,000 calories more in a day than they need. We've got too much food around us and most of us are eating it.

I think you agree... when you wrote:

"Think about it. A 6'2" male who weighs 185 pounds might have a BMR of 1950 calories. So for him to be eating PROPORTIONALLY THE SAME as the Hadza tribesmen, he would need to consume almost 4000 calories a day.

I can GUARANTEE that a typical even fit, gym going male who works a desk job and lifts / does cardio an hour every single day will get enormously fat if he ate 4000 calories a day, day in, day out."

The intriguing point of the paper was how it appeared TEE stayed about the same... it was the ratio of BMR and PA that shifted to try and hold the TEE in a "range."

And if we can agree that TEE is about the same across the populations, then we need to focus on food supply/availability as a means of solving this problem.

We can eat to just about infinity, but we can't move enough in a day to burn it back off. It's the intake.

Thanks for making me back up and re-read everything. Love it! :-)

-Shannon [smile]

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