Debunking the Thrifty Gene

by Darrin on November 5, 2010

Mr. ThriftyIs the obesity epidemic due to our innate drives to eat as much as possible and exercise as little as possible?

A “thrifty gene,” if you will, that evolved to favor those of us who easily packed on the pounds to weather the terrible famine conditions that our ancestors were forced to endure?

Hell no!

Although many people tout this hypothesis as truth, I can’t resist the challenge of debunking this bad science once and for all.

Did We Really Evolve During a Famine?

Although we cannot hop into a time machine and go back to the Pleistocene to observe our great-caveparents, it stands to reason that, like all other animals on earth, our population (not our waistlines) went up and down in response to the availability of food.

If our evolution consisted of as devastating a famine as the thrifty-geners imply we did, we simply wouldn’t still be around.

The mass extinction of large animals after humans migrated to the Americas, contemporary accounts of modern hunter-gatherers living in environments ripe with game, as well as our own omnivorism all suggest that our ancestors were able to live through times of surplus food without gaining excess weight.

Obesogenic Environments and Body Fat “Setpoints”

But if we have no “hard-wired” reason to become overweight, even obese, then why is it happening at ever-increasing levels?

Many point out that we live in an obesogenic environment compared to our stone age ancestors, that we no longer need to move our bodies to get food and build shelter, etc.

All are certainly part of the problem, but that’s just the tip of the iceberg.

Recent studies suggest that our body composition, like most of the systems in our bodies, is tightly regulated to remain near a certain “setpoint,” which is influenced primarily by our environment.

Many of the characteristics of our modern lives (chronic stress, lots of sugar, and little sleep) may even mimic famine conditions, thus raising our body fat setpoint.

I’m not saying I’m behind these theories 100%, but they are far more logical than the “thrifty gene.” For more info, check out Whole Health Source’s articles on the body fat setpoint. (Part 1, Part 2, Part 3, Part 4)

The bottom line here is that the problem isn’t you, it’s your environment.

One Last Thought for the Naysayers

The same logic and creative storytelling required to concoct the Thrifty Gene Hypothesis can also be used to “prove” the exact opposite: that we evolved to be thin.

I mean, think about it, our ancestors needed to hunt and defend themselves from predators and warring tribes. Therefore, we must have evolved to over-exercise and under-eat in all situations in order to stay lean! (Of course, I don’t actually believe this. It’s just a thought experiment.)

In the next installment of this series on willpower and fitness, I will expose the oversimplifications of the “calories in – calories out” paradigm and (if I haven’t already) make you completely give up faith in the “eat less exercise more” mantra! 🙂

Photo: Steve Snodgrass


Raymond - ZenMyFitness November 7, 2010 at 1:45 am

Sounds like a interesting series of articles.
I have never given it much thought before but its worth thinking about.
I simply think humans are like water they want the easiest path to follow so sitting around eating and watching TV is pretty attractive!

Darrin November 7, 2010 at 10:30 am


Yeah, most people would prefer sitting on the couch in front of the tube with a box of Little Debbies over running marathons and eating salads, but other animals are the same way (such as the lion example in the last post) without having the problems with fat accumulation that we do. In the next couple of posts, I’ll show how our bodies can deal with changes in activity and diet without an appreciable change in body composition.

Alykhan - Fitness Breakout November 9, 2010 at 7:19 pm


I agree that the environment is the main cause of the obesity epidemic. Just look at certain cultures and tribes that are still living like they did ages ago. Those people aren’t nearly as obese as the typical modern city dweller.


Kelly-Fitness Overhaul November 12, 2010 at 6:05 pm

These is definitely an interesting way of looking at how our bodies react to diet and exercises. I am looking forward to seeing where you are going with is. You are really an intelligent guy with a unique approach to fitness!

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