For most of human history getting into ketosis wasn’t about dieting, it was just how you lived. The body’s ability to switch from burning carbohydrates to burning fat is a core feature of our metabolism, designed to sustain us in times when food was scarce or inconsistent. Only in the last century have we abandoned this metabolic flexibility in favor of a diet centered around constant carbohydrate intake, a shift that coincided with an explosion in obesity, diabetes, and metabolic disease. The answer to the question, “why did we ever stop relying on ketones as fuel?” will lead you into a rabbit hole of corruption and broken science–we highly recommend the trip. But, what’s most important is a debunking of the keto diet as any new.

The belief that humans need a steady supply of carbohydrates to function is a recent invention, unsupported by both evolutionary history and clinical science. Our ancestors, whether hunter-gatherers or early agricultural societies, consumed diets that were naturally low in carbohydrates for much of the year. There were no processed grains, no endless supply of refined sugars, no dietary guidelines telling them to eat six servings of bread per day. Instead, humans thrived on fat and protein, using carbohydrates opportunistically when they were available—mostly in the form of seasonal fruits or root vegetables. The Inuit, the Maasai, and other indigenous populations survived for centuries on diets that were almost entirely devoid of carbohydrates, yet they exhibited none of the chronic diseases that plague modern societies.

Before the modern obesity epidemic, before the widespread consumption of processed grains and sugars, William Banting publicized the power of ketosis. In 1863, Banting, an overweight London undertaker, published Letter on Corpulence, a pamphlet detailing how he eliminated sugar, starches, and grains. His diet, which emphasized meat, fish, and fat while restricting bread, potatoes, and sweets, became wildly popular and was later referred to simply as “Banting.”

Banting was simply following the advice of his physician, Dr. William Harvey, who had been influenced by research on diabetes and carbohydrate metabolism. The results were undeniable. Banting lost weight effortlessly, felt better, and inspired countless others to do the same.

For decades after its publication, the Banting Diet was widely accepted as the best approach to weight loss and health. None of this was controversial; it was widely accepted that the body needed fat and protein and did not need carbohydrates.

It wasn’t until the 1970s—when the food industry and government agencies began promoting low-fat, high-carb diets—that Banting’s wisdom was cast aside. But with modern research now confirming what he experienced over 150 years ago, it’s clear that our departure from this optimal diet has led us into the chronic disease epidemic.

Another unrelated Banting, Dr. Frederick Banting, the co-discoverer of insulin, noted as early as the 1920s that restricting carbohydrates was the most effective way to manage diabetes. Before the advent of injectable insulin, physicians routinely prescribed low-carbohydrate, high-fat diets to control blood sugar, often with remarkable success. But as the food industry and pharmaceutical companies gained influence over public health policy, the focus shifted away from dietary intervention and toward medication. Since the 1970s, when the government first issued its low-fat dietary guidelines, the understanding that fat should be the primary fuel source for the body has been called “dangerous” and those who have challenged the government’s advice have been called quacks.

The evidence against this shift has been mounting for decades. Dr. Robert Atkins reintroduced carbohydrate restriction to the public in the 1970s, demonstrating that people could lose weight and improve metabolic health by simply eliminating sugar and grains. Though ridiculed by the medical establishment at the time, his work was rooted in clinical observations dating back to the early 20th century. Around the same time, Dr. Wolfgang Lutz published Life Without Bread, providing a scientific foundation for low-carb diets as a means of preventing disease. Drs. Michael and Mary Dan Eades, in their groundbreaking book Protein Power, expanded on these ideas, arguing that the overconsumption of carbohydrates was at the root of obesity, diabetes, and cardiovascular disease.

More recently, Drs. Stephen Phinney and Jeff Volek have taken this research further, demonstrating that ketosis is not only beneficial for metabolic health but also enhances physical performance. Their studies on endurance athletes prove that once fat-adapted, the human body is more efficient at utilizing fat for energy than it is at burning carbohydrates. This directly contradicts the prevailing belief that athletes require carbohydrate loading to sustain performance. Their work aligns with the research of Virta Health, which has clinically proven that a well-formulated ketogenic diet can reverse Type 2 diabetes, a disease long considered chronic and irreversible. The success of Virta Health’s approach has exposed the failure of conventional diabetes management, which relies on an ever-increasing dependence on insulin injections rather than addressing the root cause of the disease: carbohydrate intolerance.

Investigative journalists like Gary Taubes and researchers like Zoe Harcombe have further exposed the corruption and flawed science behind modern dietary recommendations. Taubes, in Good Calories, Bad Calories, meticulously documents how the war on fat was based on cherry-picked data and industry influence rather than solid evidence. Harcombe has similarly dissected the nutritional guidelines, demonstrating that the push for low-fat, high-carbohydrate diets was never based on rigorous science but rather on a combination of bad data and policy decisions that prioritized corporate interests over public health.

Despite overwhelming evidence supporting ketosis as a safe and effective dietary strategy, mainstream medicine continues to resist it, largely due to decades of misinformation and financial incentives tied to the pharmaceutical and processed food industries. The claim that ketosis is unnatural or dangerous and collapses under scrutiny. The real threat comes from the carbohydrate-rich diet that has been imposed on us over the last 50 years, leading to unprecedented levels of metabolic dysfunction. The human body is designed to thrive in a state of ketosis. The fact that so many people today cannot enter ketosis without severe withdrawal symptoms—commonly referred to as the “keto flu”—is itself evidence of how unnatural our modern diet has become.

If we step back and look at the broader picture, the conclusion is obvious. For millennia, humans lived in a state of metabolic flexibility, effortlessly transitioning between glucose and ketones as fuel sources depending on food availability. It is only in the last hundred years, with the mass production of cheap carbohydrates and the demonization of dietary fat, that we have become metabolically broken. The diseases modern medicine treats as inevitable—obesity, diabetes, heart disease, Alzheimer’s, cancer, mental illness, autoimmune disease, etc.—turn out to be downstream of insulin resistance. They are the consequence of abandoning the diet we were designed to eat.