More than 100 million Americans suffer from insulin resistance. That number has grown to epidemic proportions for one simple reason: We have strayed from eating in harmony with our genes.

Historically, as a hunter-gatherer species, people ate the equivalent of only 20 teaspoons of sugar a year (exclusively from fruits, berries, tubers and the like). These days, each of us eats a whopping 158 pounds per year — or about 50 teaspoons a day! There’s absolutely nothing in our genetic makeup that could have prepared our bodies to handle this kind of dramatic change, or many of the other similarly dramatic lifestyle changes to which we’ve been simultaneously exposed.

Think about it: Humans evolved in a world without grocery stores and fast-food restaurants. For virtually all of human history, our ancestors had to work to find food and had very limited access to refined foods or excess calories.

But with the appearance of 15,000 low-fat foods (a.k.a. high-sugar, high-calorie foods) on the market over the last 15 to 20 years, and our increasingly sedentary — and stressful — lifestyle, we have essentially abandoned the conditions for which our historically conditioned metabolisms are well suited. And in the process, we’ve created the perfect conditions for an epidemic of obesity, diabetes, heart disease and brain disorders.

Our bodies normally produce insulin in response to food in our stomach, particularly sugar. And, since our genetic structure evolved at a time when sugar was rarely consumed, our insulin response is designed to handle vastly lower levels of sugar than what we eat today.

Our bodies respond to our new diet of low-fat, highly processed and refined foods the only way they know how: They keep pumping out insulin — which, in excess, happens to function as a pro-inflammatory substance.

Eventually, we become resistant to all this excess insulin in our blood, just as we would become resistant to a drug. The body needs more and more of it to do the same job it once did with far less. So our insulin-production system spirals out of control, pumping ever more into our bodies, which become inflamed and metabolically imbalanced.

That’s bad, but it gets worse: Remember, hormones are message carriers. And what is all this insulin saying to the rest of our body? It’s rushing through our bloodstreams spreading the message that we are starving. The result: We start craving foods with high sugar content — the very same foods that caused the problem in the first place.