Obesity is a normal bodily response to an abnormal situation – the abundance of highly calorific and processed foods. 

Let’s start with a sobering fact. One hundred years ago, just one in 30 people were obese. Today? It’s one in three. In fact, in the United States, 71 percent of adults are overweight, and 40 percent are obese. Fat is the new normal. 

Why has this happened? Why have so many people piled on the pounds? To understand this, we have to look back in time. Way back. 

Here’s the key message: obesity is a normal bodily response to an abnormal situation – the abundance of highly calorific and processed foods. 

Humans were born to eat. 

For most of our history, we lived in survival mode. Food was scarce, and its availability unpredictable. If you found food, you ate it. 

And you’d hunt out calorie-rich foods in particular. After all, if our ancestors were gathering a pound of food per hour, with a total of 250 calories, then they might need to forage for up to ten hours just to get their daily intake. But if they could find a pound of food with a total of 500 calories, they could wrap up their daily forage in half the time. Result: Five extra hours to focus on cave paintings.

Thus, humans developed an evolutionary preference for eating and storing calories when possible. And they developed an inbuilt understanding of – and preference for – calorie-dense foods. 

We still have this inbuilt understanding today. What foods do you lust for? Lettuce? Cucumber? Or fatty, rich, sugary, starchy foods, packed with calories? In fact, studies of young children show that their preferences are correlated with calorie-density. They’ll pick a banana over berries, and even potatoes over a sweet peach: it may not taste as good, but it has the calories. 

But what was a necessity for millennia is a problem today. Our biology is still built for scarcity, but our environment is a land of plenty. Bananas, with around 400 calories per pound, no longer top the calorie-dense scale. Chocolate, cheese, bacon, and other processed foods can contain thousands of calories per pound. And while we can naturally perceive the difference between bananas and lettuce, at the top end of the scale, we struggle to tell the difference. Hardly surprising, as chocolate chip cookies and grilled cheese weren’t on the menu for our ancestors. 

The reality is, weight gain isn’t unusual or unexpected. Overweight bodies are doing what nature has taught them to do when confronted with excess calories. And today, we are confronted with more excess calories than ever.