Our human ancestors were largely herbivores. One of their foremost concerns was consuming enough calories per day to provide their bodies with the energy they required. Wouldn’t they be astounded at the ready access modern humans have to abundant sources of calories?

Sweet foods are calorie-rich. Most plant-eating animals have evolved an ability to taste sweet compounds, especially carbohydrates, and developed a particular liking for them.

It is the sodium ions present in salt that our body requires to perform a variety of essential functions. Since the body cannot make salt we are reliant on food to ensure that we get the amount of salt we require.

Fat is the richest source of calories. People and animals learn to associate the sensation of eating fat with the feeling of calories in the gut. This association is what makes fat so attractive to us. Fatty acids may also enhance the sweetness of sugar and the saltiness of salt.

It is no surprise that we have a craving for sugar, salt and fat. It is also clear that we need sugar, salt and fat to survive. So why are sugar, salt and fat demonized?

The problem is the overeating caused by the western diet and by the marketing of processed fast food that exploits our cravings for sugar, salt and fat. The food industry that arose during the 2nd half of the 20th century gave us what humans have wanted for millennia - sugar, salt and fat in formerly unheard-of quantities for very little cost. 20 years ago a bagel had 140 calories and a 3” diameter. Today a bagel has 350 calories and 6” diameter. A cheeseburger had 333 calories back then but today averages 590 calories.

And it gets worse.

David Kessler, in his recent book The End of Overeating, puts forward a compelling theory that foods high in sugar, salt and fat alter the brain's chemistry in ways that compel people to overeat. "Much of the scientific research around overeating has been physiology -- what's going on in our body," he said. "The real question is what's going on in our brain." Instead of satisfying hunger, the sugar-salt-fat combination will cause the brain to crave more.

Foods containing sugar, salt and fat stimulate the brain to release dopamine, the neurotransmitter associated with the pleasure center, Kessler suggests. Over time, the brain gets hard-wired to the point that dopamine pathways light up at even the suggestion of fast food. For example, just seeing the logo of a fast food restaurant or smelling greasy food can produce the urge to eat the food. Once the fast food is eaten, the brain releases opioids, which bring emotional relief. Together, dopamine and opioids create a pathway in our brain that can activate every time a person is reminded about the particular food. This happens whether a person is hungry or not.

The best way to begin rewiring the dopamine/opioid pathways in your brain is to visit the Harlingen Farmers Market, every Saturday from 3 - 4:30 p.m., 712 N. 77 Sunshine Strip in the courtyard at El Mercado Mall.