feet on scale, tape measure in front

Bioethics Forum Essay

The Genetics of Obesity: A New Narrative or the Same Old Story?

On a visit to my maternal grandmother, she pulled out a shoebox of family photos that I’d never seen before. They were sepia-hued, ragged around the edges, the contrast faded. One picture in particular caught my eye: a group of women of varied ages gathered on a porch. I was taken aback by what I saw: these women – my relatives, several generations in the past – were fat.  (I use this word intentionally, following injunctions from many scholars and activists who seek to reclaim the word “fat” , a way of describing bodies that do not – or in this case, would not – fit into off-the-rack clothing offered in most retail stores.)  

Why was I surprised by this? After all, my mother, uncle, grandfather, and grandmother had all waged warfare against their bodies, which seemed inclined toward an abundance of flesh. It would make sense that our ancestors, too, were sturdy and large.

Yet I had clearly internalized the message that permeates the white, middle-class United States culture in which I was raised: fatness is a modern disease, a product of food abundance, overeating, and laziness.

But this image of my great-grandmother’s mother and sisters defied this story. These women lived during the Depression, subsisted on rationed food, and spent their days laboring on farms. They worked with their bodies and didn’t have much to eat. But, still, it was undeniable: they were fat. Was it possible that the narrative I had absorbed was wrong?

 Current research into the genetic factors involved in body weight suggests that, indeed, bodies are not all meant to be thin. Body weight is highly heritable – estimates put body weight heritability somewhere between 40% and 70% (compare this to estimates for height at 80%). Researchers have identified at least 74 key genes for obesity, most of which have to do with regulating the leptin-melanocortin signaling pathway, which governs things like hunger, satiety, and the body’s energy expenditure. Given the preponderance of evidence that body size is heavily influenced by genes, one might imagine that a new narrative regarding fat bodies is emerging – one that might work against the “personal responsibility” narrative of obesity. Indeed, many herald research into the genetic factors in body weight as a way to fight fat stigma, claiming that emphasis on the genetic components of weight will finally squash the myth that body size is all about willpower.

 This is not the first time that researchers have declared that a new medical understanding of fatness will reduce stigma. The same claims were made about the classification of obesity as a disease and about the concept of an obesity epidemic. Neither of these framings has meaningfully shifted weight stigma. If anything, they have created a moral panic and provided the facade of medical concern for health as cover for anti-fat bias.

It seems to me a kind of magical thinking to assume that explaining the genetic causes of obesity will reduce stigma when that new explanation is lodged firmly within a broader project of treating, preventing, or curing fatness. In this research, fatness is still fundamentally seen as a problem to be solved, rather than simply another way of having a body. Weight loss remains the goal. As one recent study puts it, there is “urgent need for in-depth understanding of the genetic factors involved in obesity to pave the way for tailored interventions.” Whether through identifying anti-obesity genetic targets to develop new medications or identifying individuals at risk of obesity in order to provide early intervention, the research into obesity genetics is oriented toward finding new ways to help people lose weight.

This research is undergirded by the premise that fat bodies need medical treatment. Today, drugs like Ozempic, Wegovy, and now Zepbound are the favored medical solution, with enormous profit for the pharmaceutical industry and only accessible to those who can pay the $1,000 monthly price.

Efforts to develop precision medicine (which takes into account individual genetics to make treatment decisions) for weight loss are at the forefront of the medicalization of fatness. In April 2023, the weight loss mega-corporation Weight Watchers  acquired Sequence, a precision medicine weight loss company, in a $132 million deal. Its website now offers a virtual clinic and easy access to prescription medications, promising a “first-of-its-kind weight management solution.” Last month, an evaluation of a clinical trial of The Personalized Nutrition Study (POINTS), a “genetically-informed weight loss approach,” was published in Nature Communications. Direct-to-consumer genetic testing companies, such as GenoPalate and Fitness Genes, offer genetic tests to support weight loss, promising to provide information about a customer’s  risk of obesity or overweight and to offer personalized, genotype-informed recommendations for diet and exercise.

In a 2013 statement arguing against defining obesity as a disease, the AMA’s Council on Science and Public Health warned that “the medicalization of obesity could detract from collective social solutions to environmental forces that shape people’s behaviors and impact a number of conditions beyond just obesity.” Against the recommendation of this Council, the AMA House of Delegates voted to categorize obesity as a disease. Today, we see the Council’s prediction coming true. Classifying obesity as a disease has not meaningfully reduced weight stigma, and it has accelerated a conventional understanding of a obesity as an individual problem to be ameliorated with individualized medical treatments. Those treatments come with a hefty price tag, as Americans spend about $33 billion on weight loss products annually. Collective social solutions that could benefit everyone remain obscured as the lens focuses ever more narrowly on medical treatment for an individual problem.

I do believe that there is liberative potential in an emerging understanding of the role of our genetic inheritance in the size and shape of our bodies. But this potential will not be realized if we cling to the medicalization of obesity as a disease, nor if we pursue genetic knowledge for the sake of finding more effective means of losing weight.

Genetic research might help us to tell a different, better story. It might go something like this: Body diversity is a part of the human species. Human bodies come in all sorts of shapes and sizes, and none are intrinsically superior to any other. Our inherited genetic profile carries with it many of the tendencies that will interact with our environment to shape our body size – from hunger and the drive to eat, the drive to move, to the basic amount of energy that our body uses to stay alive. It is not that thin people are morally superior or even better at self-control. Rather, thin people inherit a genetic profile that predisposes them to thinness. Body size has nothing to do with one’s character. Further, thin bodies are not universally healthy and fat bodies are not necessarily unhealthy, as is emphasized by the movement for Health at Every Size. There is no one way to have a healthy body and no single way that a healthy body should look.  

While there are behaviors that might make us feel better in our bodies or extend our lives or help us avoid things like hypertension or diabetes, there is no guarantee that these behaviors will shift our body size. And this is a good thing – we should not strive to eradicate fatness. I do not want a future without fat. Instead, I want my  to ask  doctors to ask questions like, “Do you feel like you can lift the things you need to lift? Do you have the endurance to do the things you want to do? Do you have a relationship with food that feels sustainable?”

This does not mean that I want to deny access to bariatric surgery (shown to be largely effective for long-term reduction in body size as well as for reducing diabetes and hypertension) to those who would benefit from it, nor that those who want to lose weight should be prevented from doing so. (Indeed, more equitable access to bariatric surgery could be a good thing, in my view.) But I want to live in a world where, instead of focusing narrowly on fixing fatness, medicine is dedicated to a more comprehensive view of health and well-being – including food security, the availability of safe drinking water, and access to high-quality, shame-free medical care for all people.

Cassie Houtz, PhD, is a postdoctoral fellow in the Ethical, Legal, and Social Implications of Human Genetics and Genomics at the University of Pennsylvania Perelman School of Medicine.

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  1. I am an older woman, and when I gain more than ten pounds–even though I am still in the “normal” weight range–I can feel it in my joints, especially my knees. When I lose weight, I walk without pain. Even if being fat can be decoupled from metabolic disease, won’t it necessarily create more strain on joints and bones that are increasingly fragile as we age?

  2. An excellent summary. The next piece of the puzzle is that the disease of obesity is not primarily one of weight or body size, but rather one of regulation of the body’s energy state and storage, with a diverse range of pathological processes, from which there are many outcomes (one of the least important of which is body weight). When we sound medical principles to obesity by examining its true nature and relation to disease, it allows us to move away from the ‘bulk’ or anatomy of obesity, and focus instead on its physiology and impact in causing disease. In doing so we apply treatments not to change the shape of our bodies, but to allow them to last longer and function better, because we respect and appreciate them.

  3. I could not agree more. In our society, there is so much emphasis on equating fatness to health. The reality is that that extra body fat on a person does not necessarily mean that they are guaranteed to inherent some sort of comorbidity. As you’ve stated, there is health at every size. I think genetic research does/will play an important role in how we treat fatness and obesity in the future. However, I do wonder how the stigma of fatness will change in that same future. Something we as humans often forget is that certain body types go in and out of “fashion” as decades pass. I remember in the early 2000s a slender and “skinny” body was what everyone wanted. Now, it’s having a small waist with enhanced female features like larger breasts, bottom, and lips. I bring this up because stigmas are a major motivating factor for persons to seek solutions and “fix” their “flaws”. I think there should be more talk on how health and perception of health is highly individualized and that looking a certain way does not define truly what goes on inside.

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