We know that processed foods are bad for us, and that though they may be tasty, they do not bring us any nutritional benefits. How come we find it so hard to say no to those chips, donuts, and crackers?
Many processed foods — such as potato chips, donuts, crackers, cookies, and fries — have a high content of both (saturated) fat and carbohydrates.
However, they also have little to no nutritional value.
Instead, they are packed with “empty calories,” meaning that they can build up our fat levels without providing us with much energy.
If we consistently eat processed foods, or if our diets consist mainly of these, this will gradually increase our risk of metabolic conditions, such as obesity or diabetes, and of other complex diseases, such as cancer.
None of this is new information. Still, though we are aware of the consequences and know which foods are better for our health, many of us still find it difficult to steer clear of these tempting snacks. Why is this?
Researchers from four countries — Germany, Switzerland, the United States, and Canada — have now conducted a series of experiments investigating what happens in the brain when a person is confronted with foods high in carbs, foods that have a high fat content, and foods that are high in both carbs and fats (typically processed foods).
The researchers’ findings indicate that, while we may be pretty good at instinctively estimating the nutritional value of foods that are rich either in carbs or in fats, we seem to be worse at evaluating the nutritional value of processed foods, which are high in both.
“The biological process that regulates the association of foods with their nutritional value,” says senior author Dana Small, from Yale University’s Modern Diet and Physiology Research Center in New Haven, CT, “evolved to carefully define the value of a food so that organisms can make adaptive decisions.”
“For example, a mouse should not risk running into the open and exposing itself to a predator if a food provides little energy,” she explains.
When it comes to processed foods, however, this age-old “cost vs. benefit” mechanism seems to malfunction in humans — so suggests the new study, published in the journal Cell Metabolism.
The main study involved 206 participants, who were, in the first instance, shown images of snacks whose calories came primarily from either their content of fats, carbs, or a mix of the two.
All of these snacks were then rated by each participant on four counts: liking, familiarity, estimated energy density, and caloric content.
“On a subsequent day,” the scientists explain in their paper, “[the participants] arrived [with empty stomachs] to the laboratory and were fed a standard breakfast of 426 [kilocalories] from orange juice, cheddar cheese, whole-wheat toast, white toast, strawberry jam, and butter.”
Source: Medical News Today