Not all sugars are created equal. Nor do they spark equal responses in our brains. Research completed recently and presented at the American College of Neuropsychopharmacology annual meeting in Phoenix, Arizona supports previous findings that fructose makes us hungry, while glucose makes us feel full. Fructose, it seems, is the gateway drug to more fructose and potential obesity.
Fructose, the simple sugar found in fruit, is also added to lots of foods as “refined sugar” in the form of high-fructose corn syrup. Glucose is the sugar we get after our bodies break down complex carbs.
When fructose is shot straight into the brain of rodents it provokes feeding, according to an article about the new research on ingredientsnetwork.com. But when the mice get a hit of glucose, they don’t eat. Preliminary studies in people have also shown that glucose reduces activity in the hypothalamus—an event that is associated with metabolic satiety—whereas fructose does not.
Researcher Kathleen Page of the Keck School of Medicine of the University of Southern California along with researchers in the Department of Psychology at the University of Southern California took these findings further using functional magnetic resonance imaging (fMRI) and food porn. The subjects, 24 young men and women between the ages of 16 and 25, drank a beverage of either glucose or fructose. Then, they were shown images of things like chocolate cake. Researchers monitored their brains with fMRIs and also recorded how much participants reported they wanted to eat.
The brain scans revealed that for those who drank the fructose drink, the images of chocolate cake were more likely to spark a part of the brain’s “reward circuit” called the nucleus accumbens, increasing their desire for food. The fructose drink also resulted in a higher level of hunger and motivation to eat compared to the glucose drink.