Rather than being some kind of disorder or failure of willpower, weight gain is largely a normal response, by normal people, to an abnormal situation.
The Thrifty Gene Theory: Survival of the Fattest
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
It’s been said that “Nothing in biology makes sense except in the light of evolution.” The known genetic contribution to obesity may be small, but in a certain sense, you could argue, it’s all in our genes. The excess consumption of available calories may be hardwired into our DNA.
We were born to eat. Throughout most of human history and beyond, we existed in survival mode, in a context of unpredictable scarcity. So, we’ve been programmed with a powerful drive to eat as much as we can, while we can, and just store the rest for later. Food availability could never be taken for granted, so those who ate more in the moment and were best able to store more fat for the future might better survive subsequent shortages to pass along their genes. So, generation after generation, millennia after millennia, those with lesser appetites may have died out, and those who gorged may have selectively lived long enough to pass along their genetic predisposition to eat and store more calories. That may be how we evolved into such voracious calorie-conserving machines. Now that we’re no longer living in such lean times, though, we’re no longer so lean.
What I just described is the “thrifty gene” concept proposed in 1962: the proposal that obesity is the result of a “mismatch” between the modern environment and the environment in which we evolved. It’s like we’re now polar bears in a jungle. All that fur and fat may have given them an edge up in the Arctic, but would be decidedly disadvantageous in the Congo. Similarly, a propensity to pack on the pounds may have been a plus in prehistoric times, but can turn into a liability when our scarcity-sculpted biology is plopped down into the land of plenty. So, it’s not gluttony or sloth. Obesity may simply be a normal response to an abnormal environment.
Much of our physiology is finely tuned to stay within a narrow range of upper and lower limits. If we get too hot, we sweat; if we get too cold, we shiver. Our body has mechanisms to keep us in balance. In contrast, our bodies have had little reason to develop an upper limit to the accumulation of body fat. In the beginning, there may have been evolutionary pressures to keep lithe and nimble in the face of predation. But, thanks to things like weapons and fire, we haven’t had to outrun as many saber-tooth tigers for about two million years or so. This may have just left our genes with the one-sided selection pressures to binge on every morsel in sight, and stockpile as many calories onto our bodies as possible.
What was once adaptive is now a problem––or at least so says the thrifty gene hypothesis that originated more than a half century ago. It provides a simple and elegant explanation for the modern obesity epidemic and was quickly embraced by scientists and lay people alike. Although Neel later distanced himself from the original proposal, despite remaining mostly theoretical, the basic premise remains largely accepted by the scientific community. The implications are profound.
In 2013, the American Medical Association voted to classify obesity as a disease (against the advice of their own Council on Science and Public Health). Not that it necessarily matters what we call it (a rose by any other name would cause just as much diabetes), but disease implies dysfunction. Bariatric drugs and surgery are not correcting some anomaly of human physiology. Our bodies are just doing what they were designed to do in the face of excess calories. Rather than some sort of disorder, weight gain is largely a normal response, by normal people, to an abnormal situation. More than 70 percent of Americans are now overweight—it’s literally normal.
A body gaining weight when excess calories are available for consumption is behaving normally. Efforts to curtail such weight gain with drugs or surgery are not efforts to correct an anomaly in human physiology, but rather to deconstruct and reconstruct its normal operations at the core.
Please consider volunteering to help out on the site.
- Dobzhansky T. Nothing in biology makes sense except in the light of evolution. Am Biol Teach. 1973;35(3):125-9.
- Neel JV. Diabetes mellitus: a “thrifty” genotype rendered detrimental by “progress”? Am J Hum Genet. 1962;14:353-62.
- Genné-Bacon EA. Thinking evolutionarily about obesity. Yale J Biol Med. 2014;87(2):99-112.
- Anderson RM, Brackenridge BP. Polar bears in the jungle: reflections on obesity and overeating. Diabetes Educ. 1999;25(4):521-3.
- Egger G, Swinburn B. An "ecological" approach to the obesity pandemic. BMJ. 1997;315(7106):477-80.
- Pimentel GD, Ganeshan K, Carvalheira JB. Hypothalamic inflammation and the central nervous system control of energy homeostasis. Mol Cell Endocrinol. 2014;397(1-2):15-22.
- Speakman JR. Thrifty genes for obesity, an attractive but flawed idea, and an alternative perspective: the “drifty gene” hypothesis. Int J Obes (Lond). 2008;32(11):1611-7.
- McFerran B, Mukhopadhyay A. Lay theories of obesity predict actual body mass. Psychol Sci. 2013;24(8):1428-36.
- Neel JV. The study of natural selection in primitive and civilized human populations. 1958. Hum Biol. 1989;61(5-6):781-810.
- American Medical Association’s Council on Science and Public Health. American Medical Association’s Council on Science and Public Health report 420 (A-13). 2013.
- The Council on Science and Public Health. Report of the Council on Science and Public Health: CSAPH report 3-A-13. 2013.
- Urgently needed: a framework convention for obesity control. Lancet. 2011;378(9793):741.
- National Center for Health Statistics. Health, United States, 2017: With special feature on mortality. Hyattsville, MD. 2018.
- Katz D. Obesity . . . be dammed!: what it will take to turn the tide. Harvard Health Policy Rev. 2006;7(2):135-51.
- Myslobodsky M, Ingraham LJ. Managing the pandemic of obesity: siding with the fox or the hedgehog? Obes Facts. 2009;2(6):384-92.
Video production by Glass Entertainment
Motion graphics by Avocado Video
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
It’s been said that “Nothing in biology makes sense except in the light of evolution.” The known genetic contribution to obesity may be small, but in a certain sense, you could argue, it’s all in our genes. The excess consumption of available calories may be hardwired into our DNA.
We were born to eat. Throughout most of human history and beyond, we existed in survival mode, in a context of unpredictable scarcity. So, we’ve been programmed with a powerful drive to eat as much as we can, while we can, and just store the rest for later. Food availability could never be taken for granted, so those who ate more in the moment and were best able to store more fat for the future might better survive subsequent shortages to pass along their genes. So, generation after generation, millennia after millennia, those with lesser appetites may have died out, and those who gorged may have selectively lived long enough to pass along their genetic predisposition to eat and store more calories. That may be how we evolved into such voracious calorie-conserving machines. Now that we’re no longer living in such lean times, though, we’re no longer so lean.
What I just described is the “thrifty gene” concept proposed in 1962: the proposal that obesity is the result of a “mismatch” between the modern environment and the environment in which we evolved. It’s like we’re now polar bears in a jungle. All that fur and fat may have given them an edge up in the Arctic, but would be decidedly disadvantageous in the Congo. Similarly, a propensity to pack on the pounds may have been a plus in prehistoric times, but can turn into a liability when our scarcity-sculpted biology is plopped down into the land of plenty. So, it’s not gluttony or sloth. Obesity may simply be a normal response to an abnormal environment.
Much of our physiology is finely tuned to stay within a narrow range of upper and lower limits. If we get too hot, we sweat; if we get too cold, we shiver. Our body has mechanisms to keep us in balance. In contrast, our bodies have had little reason to develop an upper limit to the accumulation of body fat. In the beginning, there may have been evolutionary pressures to keep lithe and nimble in the face of predation. But, thanks to things like weapons and fire, we haven’t had to outrun as many saber-tooth tigers for about two million years or so. This may have just left our genes with the one-sided selection pressures to binge on every morsel in sight, and stockpile as many calories onto our bodies as possible.
What was once adaptive is now a problem––or at least so says the thrifty gene hypothesis that originated more than a half century ago. It provides a simple and elegant explanation for the modern obesity epidemic and was quickly embraced by scientists and lay people alike. Although Neel later distanced himself from the original proposal, despite remaining mostly theoretical, the basic premise remains largely accepted by the scientific community. The implications are profound.
In 2013, the American Medical Association voted to classify obesity as a disease (against the advice of their own Council on Science and Public Health). Not that it necessarily matters what we call it (a rose by any other name would cause just as much diabetes), but disease implies dysfunction. Bariatric drugs and surgery are not correcting some anomaly of human physiology. Our bodies are just doing what they were designed to do in the face of excess calories. Rather than some sort of disorder, weight gain is largely a normal response, by normal people, to an abnormal situation. More than 70 percent of Americans are now overweight—it’s literally normal.
A body gaining weight when excess calories are available for consumption is behaving normally. Efforts to curtail such weight gain with drugs or surgery are not efforts to correct an anomaly in human physiology, but rather to deconstruct and reconstruct its normal operations at the core.
Please consider volunteering to help out on the site.
- Dobzhansky T. Nothing in biology makes sense except in the light of evolution. Am Biol Teach. 1973;35(3):125-9.
- Neel JV. Diabetes mellitus: a “thrifty” genotype rendered detrimental by “progress”? Am J Hum Genet. 1962;14:353-62.
- Genné-Bacon EA. Thinking evolutionarily about obesity. Yale J Biol Med. 2014;87(2):99-112.
- Anderson RM, Brackenridge BP. Polar bears in the jungle: reflections on obesity and overeating. Diabetes Educ. 1999;25(4):521-3.
- Egger G, Swinburn B. An "ecological" approach to the obesity pandemic. BMJ. 1997;315(7106):477-80.
- Pimentel GD, Ganeshan K, Carvalheira JB. Hypothalamic inflammation and the central nervous system control of energy homeostasis. Mol Cell Endocrinol. 2014;397(1-2):15-22.
- Speakman JR. Thrifty genes for obesity, an attractive but flawed idea, and an alternative perspective: the “drifty gene” hypothesis. Int J Obes (Lond). 2008;32(11):1611-7.
- McFerran B, Mukhopadhyay A. Lay theories of obesity predict actual body mass. Psychol Sci. 2013;24(8):1428-36.
- Neel JV. The study of natural selection in primitive and civilized human populations. 1958. Hum Biol. 1989;61(5-6):781-810.
- American Medical Association’s Council on Science and Public Health. American Medical Association’s Council on Science and Public Health report 420 (A-13). 2013.
- The Council on Science and Public Health. Report of the Council on Science and Public Health: CSAPH report 3-A-13. 2013.
- Urgently needed: a framework convention for obesity control. Lancet. 2011;378(9793):741.
- National Center for Health Statistics. Health, United States, 2017: With special feature on mortality. Hyattsville, MD. 2018.
- Katz D. Obesity . . . be dammed!: what it will take to turn the tide. Harvard Health Policy Rev. 2006;7(2):135-51.
- Myslobodsky M, Ingraham LJ. Managing the pandemic of obesity: siding with the fox or the hedgehog? Obes Facts. 2009;2(6):384-92.
Video production by Glass Entertainment
Motion graphics by Avocado Video
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Title
The Thrifty Gene Theory: Survival of the Fattest
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
If weight gain is largely a normal response, by normal people, to an abnormal situation, what exactly is that abnormal situation? Calorie-Rich-And-Processed Foods (I’ll let you work out the acronym!). That’s the topic we’ll turn to next.
This is the third in an 11-part video series on the history of the obesity epidemic. If you missed the first two, see The Role of Diet vs. Exercise in the Obesity Epidemic and The Role of Genes in the Obesity Epidemic.
There are eight more coming up:
- Cut the Calorie-Rich-And-Processed Foods
- The Role of Processed Foods in the Obesity Epidemic
- The Role of Taxpayer Subsidies in the Obesity Epidemic
- The Role of Marketing in the Obesity Epidemic
- The Role of Food Advertisements in the Obesity Epidemic
- The Role of Personal Responsibility in the Obesity Epidemic
- The Role of Corporate Influence in the Obesity Epidemic
- The Role of the Toxic Food Environment in the Obesity Epidemic
And if you really want to watch them all now, you can grab a digital download from the webinar I did in January: What Triggered the Obesity Epidemic?
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