“I’m addicted to chocolate!”

“I NEED a Dr. Pepper right now.”

“I’m obsessed with McDonald’s French fries.”

Do these statements sound familiar? Many of us have heard these or similar remarks from friends, loved ones, or even ourselves. The truth is, our bodies are predisposed to crave and want these kinds of calorie-rich foods. Our palates have been shaped by millions of years of evolutionary necessity to desire foods high in fat, sugar, and salt.

Why Do Humans Crave High-Calorie Foods?

Calories are translated in our bodies as energy, and provide essential nutrients required for human functioning. The most calorie-dense foods, and therefore most energy-rich, are those high in fat, carbohydrates, and sugar. The reason humans prefer energy-rich foods is because for millions of years, food was difficult to obtain, particularly energy-rich foods. Essential nutrients required for human functioning can be found in high concentration in calorie-dense foods, so it was important for the brain to develop a way to reinforce the behavior of eating these foods. These types of “hyper palatable foods” release chemicals that work to activate the reward system in the brain to release dopamine. This release of dopamine is the brain’s way of encouraging humans to seek out those foods that fed their body best. A feeling of euphoria is created each time these foods are consumed.

French researchers developed a study to look at this effect on animals. One group of animals was allowed to eat freely, while the other was put on a restricted food allowance. Both sets were then exposed to a chocolate cereal high in sugar and fat to gauge what effect hunger had on attraction to calorie-dense foods. The researchers discovered that the hungry, restricted animals ran only slightly faster towards the food than freely fed animals. However, whether the animals were restricted or freely fed had no effect on how much the animals ate of these calorie-dense foods. In other words, the freely fed animals ate as much as the restricted animals! This experiment proved that animals will work for foods that are high and sugar and fat even if they are not hungry.[1]

The world we live in today is obviously quite different. We are no longer hunter-gatherers and can find a wide variety of foods at our local supermarket. The industrialization of society was much quicker than our bodies could adapt to evolutionarily, though, and our brains are still hardwired to seek out the most energy-rich foods possible. Understanding this biological process can help you make smarter choices when it comes to food options and eating practices. If you are interested in understanding these concepts in more depth, a fantastic resource is the book The End of Overeating, by Dr. David Kessler, former head of the Food and Drug Administration.


[1] Kessler, Davis. (2009). The End of Overeating. New York, NY: Rodale.

Edited by Jacques Courseault, M.D.