Sugar ain't sugar: fructose makes you hungrier than glucose, study finds

While the standard line is that ‘sugar is sugar’, new research has shown that glucose and fructose can have different effects on hunger and satiety.

Differences in the way the human body metabolises the two sugars could impact the way we respond to food, enhancing the reward value of high-calorie food and promoting eating.

Kathleen A Page and colleagues from the University of Southern California conducted fMRI scans on 24 participants over two days. On one day, the participants were given drinks sweetened with fructose; on the other, they were given drinks sweetened with glucose.

The participants were shown images of high-calorie foods and asked to report their level of hunger and desire for the foods.

After consuming the fructose-sweetened drinks, the participants reported greater hunger and exhibited greater activity in the orbitofrontal cortex and visual cortex of the brain in response to the images than after they’d consumed the glucose-sweetened drinks.

In addition, the researchers found that fructose produced a smaller plasma insulin response than glucose.

The researchers then upped the ante, presenting participants with a choice of delayed monetary rewards or immediate high-calorie food rewards. They found that participants displayed greater willingness to give up monetary rewards for food rewards after ingesting fructose than after ingesting glucose.

The researchers say the results suggest that ingesting fructose may not produce the same satiety effects as glucose.

The research was published in the journal PNAS.