I’m hungry. There’s nothing I want to eat.

I’ve been doing fieldwork for over a year, and the thought of making another bowl of noodles with fried egg is entirely unappealing. I could walk down the road and have a slightly different bowl of noodles from a food stand, or I can dig through my box of hyper-processed snacks.

Cookies. Crackers. Spreadable chocolate. Starch-white bread.

Guilt wriggles through me as I think about the ratio of nutrients to calories in this ‘meal’. I’ve done nothing to earn the metabolism that allows me to eat processed sugar and fat and still be considered ‘thin’ by most standards. I know that I’ll be able make self-deprecating jokes about this pathetic attempt to feed myself and escape with my label as a ‘healthy person’ intact.

Thin, after all, is often synonymous with healthy. As a middle-class white woman from southern Ontario, I’m thin in a culture that reveres thinness as the ultimate symbol of health and discipline. Never mind that I just ate four Oreos with peanut butter for dinner. No amount of processed food can rob me of the morality that I’ve done nothing to earn.

A cursory look at Western media might give the impression that a thin, toned frame is the natural embodiment of female beauty. However, ethnographic and historical research make it clear that ideals of health and body type are every bit as cultural as the clothes that envelop those bodies. For example, adolescent girls in Mexico felt that a “slender but curvy” physique was ideal amongst their peers, and they felt that thicker girls “don’t care about losing weight.” This was in contrast to depictions of European-American girls who strive to be ‘thin.’

Western narratives that surround weight loss and exercise lifestyles in both social and print media are equally culturally-determined. The notion that anyone can fit into a size 6 dress with enough hard work and patience is reinforced over and over again on multiple platforms where before-and-after pictures depict a universal truth: just work harder. There’s a six pack in there. Keep digging.

But this idea that anyone can achieve a specific kind of lithe body through discipline alone flies in the face of everything we know about human evolution. It is unreasonable to assume that every single person on the planet can achieve a particular size or shape. Humans vary. Without variation, we wouldn’t be the widespread and diverse species that we are today. Without variation, we wouldn’t find differences in our ability to digest lactose, thermoregulate ourselves, or protect ourselves from UVA radiation. Without genetic variation humans simply wouldn’t be. Variation has shaped all 7.8 million of us.

Most people are willing to acknowledge that a short person can’t become tall. No combination of chia seeds and açai berries will reduce someone’s height by a few inches. Tanning oil and whitening cream may cause short-term changes in skin tone, but few reasonable people would argue that a simple juice cleanse will eliminate my freckles and propensity for sunburns. However, if you look at the criticisms leveled against women in particular whose bodies do not fit the fit mold, everything we know about genetic variation and bell curves go out the window.

We live in a world where evolutionary biology is misconstrued and contorted to support unsubstantiated fads like attachment parenting and paleo diets, but where rules about simple genetic variation are steadfastly ignored. The circumference of your rib cage can shrink by 4 inches, you just need to work a little harder. Have you considered high intensity interval training?

It’s tempting to point the finger at genetics as the sole culprit for the disparity between what we are told is feasible vs. what is realistic. Like any social problem worth solving, however, it’s not that simple. In fact, a large-scale study concluded that the combination of 32 individual genes accounted for a mere 1.45% of the observed variation in the BMI of 250 000 individuals from multiple populations*. In other words, a lot of other things are happening. Genes were only a few drops in the proverbial obesity bucket.

Part of what makes understanding trends in weight and weight loss so difficult is that they are not simply the product of our own personal choices in adulthood. Our experiences in utero and as infants can have long-lasting effects on important physiological traits, such as metabolism and blood pressure regulation. These phenomena are examples of epigenetics — changes in the way a gene is expressed, rather than a change to the genetic code itself. It may be true that metabolism can be bolstered by regular physical activity, but even the most disciplined exercise regime seems unlikely to reverse decades-old epigenetic changes.

Body weight and fat distribution are the result of a seemingly endless and ever-changing list of factors including our appetites and cravings, metabolic disorders, weight at birth, stress levels, the amount of heat that our bodies produce after we eat a meal, personality types, gut microbiomes, activity levels, weight at birth, and other epigenetic phenomena.

Though it’s easy to assume that height is completely dependent on genetics, a recent cohort study demonstrated that adolescents with ‘high-normal’ and ‘overweight-obese’ BMIs were at an increased risk for shorter-than-predicted stature based on their parental height. So, what is one of the main influencing factors on BMI in adolescents? Nutrition. And what influences nutrition? Socioeconomic status. And parental education. And geographic location. And what influences geographic location?

Socioeconomic status. Again.

The failure of public policy to address the lack of food in poor communities adds yet another barrier in the way of adequate nutrition. To pretend that diet is independent from a person’s income is to ignore the impact that poverty can have on the physical and mental health of people in all stages of life. The on-going nature of settler colonialism in North America, for example, has been forcing people off their land for centuries. This has then been followed with prohibitively high costs of food in some parts of Canada, where a simple head of lettuce will nearly put you in debt. All that is to say nothing of the loss of traditional hunting knowledge and intergenerational trauma that comes from decades of the Canadian government separating Indigenous children from their families.

Even if it were true that diet was the main component to an idealized body type, access to whatever superfoods are in vogue at the time will not be equal across all income levels and geographic locations. Humans exist on a bell curve. Some of us are short and stout, some of us are long and lean. Some were born to race horses, while others were plucked from the crowd of potential quarterbacks before we finished high school. Some have grown up with consistent access to affordable, nutritious food and clean drinking water, and some haven’t. To believe that we are all capable of achieving a particular height-to-weight ratio is to ignore the effects of biology, epigenetics, and socioeconomic factors on health.

The guilt I carry inside my thin frame doesn’t just come from the knowledge that I can eat garbage for dinner without criticism. The guilt comes from knowing that the positive encounters that I have with people in this world are, in part, a result of things that I have had no control over. My white skin and visible collar bones ensure that I will typically be complemented long before I will be discriminated against. Best-selling author and New York Times columnist Lindy West once wrote:

As a woman, my body is scrutinized and policed. As a fat woman, my body is also lampooned, openly reviled, and associated with moral and intellectual failure. My body limits my job prospects, access to medical care, and, supposedly, my ability to be loved.

Cultural biases against fat people run deep, and the combination of body size with other marginalizing identities even more so. But perhaps with an improved understanding of the variation in human body size coupled with the myriad biological and social factors that affect weight, we can improve our understanding of the bell-shaped curve of human bodies. Those of us that do not face rampant discrimination because of the shape of our body or the colour of our skin are obligated to call out fat-shaming and misinformation when we see it. Oreo-induced guilt isn’t likely to help anyone.