The name says it all.
Our ancestors foraged for food by hunting and gathering.
These are presumably high-energy tasks, especially if your livelihood depends on it.
Hunting and gathering is entirely different in Western culture.
My wife “gathers” by going to the grocery store and I hunt by . . . well I don’t really hunt anything. She hunts for us at the store.
We drive to the store in our automobiles.
We have our stuff delivered from Amazon to our doorsteps.
Skype and Google Hangouts allows us to conference without taking horse and buggy across the country.
These are examples of modern conveniences that keep us from being active.
This is not necessarily bad.
We use our stored energy to produce other things and get better results, results that hopefully will propel us forward in a positive way.
It seems logical and has been argued that our lack of energy expenditure is responsible for our obesity.
However, one study puts this theory into question.
A freely accessed paper on PLOSone studied a modern hunter-gatherer society - the Hazda from Northern Tanzania - that continue to this day to hunt and gatherer on foot using bows, axes, digging sticks and nothing at all modern.
Sounds like work.
The Hazda get calories from foraging for wild foods and eat mainly tubers, berries, baobab fruit, honey as well as small and large game.
The researchers studied the Hazda over an 11-day period by measuring daily energy expenditure (using doubly-labeled water method for you geeks) as well as resting metabolic rate by having participants wear a portable respiratory system.
They measured walking distances by having the Hazda men and women wear portable GPS devices.
Data was compared to Westerners based on available data from previous studies.
The Hazda were found to be leaner and had less body fat than the Westerners . . . which is no surprise.
However . . .
The total energy expenditure among the Hazda group was similar to Western populations.
It turns out that the Hazda had greater physical activity levels, but did not burn as much energy at rest in comparison to the Westerners.
The effect of this was that total energy expenditure was about equal.
The authors concluded:
the difference in obesity prevalence between populations result primarily from differences in energy intake rather than expenditure
The primary factor may be what we eat and not the energy that we burn with activity.
Remember the Hazda eat root vegetables, fruits and game.
What do we eat?
High-caloric density junk food.
Obesity may be less a problem with inactivity and more about the caloric density of our foods.
Our total energy expenditure may be more complex and set based on a complex interplay of physiology and genetics.
We may be hard wired to just move around at about the same level no matter what. Lock me in a square room and I would probably walk around the room all day . . . in circles . . . thinking about how to get out.
Some people are more fidgety than others and can burn calories the equivalent of a long run every day.
This is why some people stay slim without effort and consume whatever they want.
This was not an intervention study, so I would not conclude that this is an excuse to be a sloth and avoid activity.
The benefits of being active are proven and well-studied.
However, it may help us better understand that it is not necessarily our lack of activity making us obese, but points more strongly to food intake as the real problem.
Learn more about the Hazda
Image Credit: Hazda archery by Woodlouse on Flickr