It’s normal for young people to prefer sweet foods. But as they reach adulthood, these preferences typically decline. However, in people with obesity, the drop-off may not be as sharp.
New research suggests there could be a reason for this phenomenon. It may be that the brain’s reward system operates differently in people who are obese compared to those who are thinner.
The researchers studied 44 subjects. Twenty of these individuals were normal weight, the other 24 were considered obese.
Each of the participants tasted several different drinks with varying levels of sugar to find out what degree of sweetness they preferred. Then, researchers conducted PET scans to find the dopamine receptors linked to rewards in the participants’ brains. This is a “feel good” chemical in your brain.
“We find that both younger age and fewer dopamine receptors are associated with a higher preference for sweets in those of normal weight. However, in people with obesity, that was not the case in our study,” said first author M. Yanina Pepino, PhD.
In those who were obese, the brain’s reward system appeared to work differently. The relationship between sweetness preferences and dopamine receptors didn’t follow the same pattern as it did in those of normal weight.
The study authors suggest this might be due to insulin resistance or other metabolic change linked to obesity, as some of the obese subjects had higher blood glucose and insulin concentrations. Additionally, some of them were becoming resistant to insulin.
Combined, the researchers believe these factors could alter the brain’s response to sweets.
“There is a relationship between insulin resistance and the brain’s reward system, so that might have something to do with what we saw in obese subjects,” said co-author Tamara Hershey, PhD.
“What’s clear is that extra body fat can exert effects not only in how we metabolize food but how our brains perceive rewards when we eat that food, particularly when it’s something sweet.”
SOURCE: Age, obesity, dopamine appear to influence preference for sweet foods. News Release. Washington University School of Medicine in St. Louis. Jun 2016.