Despite our best intentions to stay healthy, we all have one or two junk foods that we could never imagine giving up (mine are french fries and triple chocolate chip cookies). Figuring out how the body regulates preferences for these foods would make it easier for us to maintain our weight and health, but scientists have never really been certain how this works.
Now a team of researchers from the University of Cambridge in the UK have discovered a gene that might be responsible for whether you prefer high fat or high sugar foods, and it could lead to better treatment for metabolic disorders like obesity.
In a new study published in the journal Nature Communications, the Cambridge team showed that pathways in the brain involving the melanocortin-4 receptor (MC4R) play a critical role in food choice. They also found that gene mutations which disrupt these pathways result in the subject overwhelmingly preferring fat over sweet foods.
Participants in the study included 14 people with MC4R mutations, who were given a series of identical meals with varying levels of fat and sugar. Although they couldn’t tell the differences in sugar or fat content, the MC4R subjects ate significantly more of the high-fat foods than control groups, while consuming less of the high-sugar meals.
“Our work shows that even if you tightly control the appearance and taste of food, our brains can detect the nutrient content,” says Professor Sadaf Farooqi from the Wellcome Trust–Medical Research Council Institute of Metabolic Science at the University of Cambridge, who led the research team.
“Most of the time we eat foods that are both high in fat and high in sugar. By carefully testing these nutrients separately in this study, and by testing a relatively rare group of people with the defective MC4R gene, we were able to show that specific brain pathways can modulate food preference.”
The results are exciting because this is the first study to show a definitive link between genetics and preference for certain types of junk foods. While obesity is generally a mix of inherited and environmental causes, identifying and treating the genetic component could make it much easier for overweight people to lose weight and improve their health.
Farooqi and her team also believe the research supports a commonly held theory that humans and animals evolved a preference for high fat food to help us survive in times of food scarcity.
“When there is not much food around, we need energy that can be stored and accessed when needed,” she says. “Fat delivers twice as many calories per gram as carbohydrates or protein and can be readily stored in our bodies. As such, having a pathway that tells you to eat more fat at the expense of sugar, which we can only store to a limited extent in the body, would be a very useful way of defending against starvation.”
Q: Which types of junk foods do you prefer — cookies and candy or pizza and hot dogs? Let us know in the comments below.