Have we evolved to be fat? Debunking the myth of genetic guilt

In the annals of scientific history, the year 2003 stands out as a monumental milestone. A global consortium of researchers from 20 universities accomplished a feat that would redefine our understanding of human biology: the sequencing of the human genome. Unveiling the intricacies of our genetic code, this groundbreaking achievement revealed a staggering truth — 99.5% of our DNA is identical across individuals. It's the remaining 0.5% that sets us apart, making each of the 8 billion individuals on Earth uniquely distinct.

It is to this 0.5% variation that we owe our unique traits as well as our susceptibility to various diseases. Genetic variants have long proven to be determining factors for our body mass index (BMI), fat storage, and tendency to obesity. Minute differences in our genetic makeup unfold the story of why some people effortlessly maintain a svelte figure while others grapple with weight management.

Understanding the nuances of our shared genetic heritage can empower individuals to embrace their unique biological blueprints, fostering a sense of self-acceptance and dispelling notions of culpability.

Transport yourself to a bygone era, approximately 2.5 million years ago, when human-like creatures embarked on the journey of populating the East African savannahs. Picture a world teeming with wide open spaces, pristine nature, and a delicate balance between early humans and the diverse array of animals and predators sharing their ecosystem. In this ancient dance for survival, where food was not a daily guarantee, our ancestors navigated a landscape heavily influenced by climatic variability.

Let your imagination roam through the challenges faced by prehistoric humans in the quest for sustenance. Contrary to the fantastical images of mammoth feasts, the reality was a strategic pursuit of smaller prey. Hunting successes were sporadic, and for larger kills, early humans likely had to wait for higher predators to satiate themselves before approaching the carcass. A symbiotic relationship with the fruits and plants gathered by prehistoric women provided a crucial alternative to fill stomachs when hunting proved elusive.

The evolutionary adaptation of our ancestors to live in this harsh environment and their enhanced ability to extract energy from food and store it as fat allowed humanity to flourish. By understanding the evolutionary forces that shaped our predisposition to store fat, individuals can find solace in the realization that their struggles are deeply rooted in a legacy of adaptation.

One hypothesis stands out as a key player in shaping our biological response to food scarcity — the thrifty gene hypothesis. Conceived in 1962 by geneticist James Neel, this theory proposes that throughout our evolutionary journey, the pressure of food scarcity favored the selection of mutations that predispose us to metabolic thriftiness, a fancy term for fat accumulation.

Once advantageous for survival, these very genetic adaptations have become a double-edged sword in the face of modern abundance. Towards the end of the last century, the food security advantage that our ancestors fought so hard for took an unexpected turn, contributing to the global rise of obesity and related health issues.

However, before attributing all blame to our DNA, it's imperative to recognize the dynamic interplay between genes and environment. The modern obesogenic environment, characterized by an abundance of easily accessible and energy-dense food, has triggered an epidemic of metabolic disorders. Our overweight bodies are merely responding to the environment they navigate. To be fair, regardless of how thrifty our genes can be, if we were brought back to live in the environment of the average person 200 years ago, we would all be very thin, rocking perfect blood sugar levels, and blood pressure.

While we might not be able to reshape our DNA, we may be very well in state to reshape our environment and our approach to health. Armed with insights into the biological underpinnings of weight management, individuals can reclaim agency over their well-being.

More about this in the following posts… and for those who cannot wait, you might consider to add my book Planet Fat to your book shelves 😊