Sugar may be bad for you, but if you think you’re being healthier by going for a substitute sweetener, you may as well stick with the original, says a new study.

Researchers at the University of Southern California found that eating subsitute sweetners could be be setting people up for an even unhealthier snack later.

In studying how sugar affects the motivation to eat, the researchers used brain scans to show that a type of sugar called fructose is associated with an area of the brain that processes reward and promotes eating.

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“Glucose is found in most starchy foods, including bread, pasta and fruit, while the natural source of fructose is fruit and vegetables," explains study leader Dr. Kathleen A. Page. "But the biggest source of fructose in the American diet is sugar sweeteners.”

The study was small, involving just 24 people, who were given drinks sweetened with fructose on one day and glucose on another day. (Regular table sugar is largely made up of sucrose.) They were shown images of high-calorie foods, then asked to gauge their level of hunger and desire for the different foods. After the fructose drinks, participants reported feeling hungrier.

In a further study, the scientists presented participants with a choice of delayed monetary rewards or immediate high-calorie food rewards. Again, the study subjects were more willing to go for the food reward after drinking the fructose shake.

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How sweet is it?

Stevia: Plant-derived sugar alternative

High fructose corn syrup: Corn is pure glucose, but enzymes are added to convert it into fructose

Aspartame: (Equal, NutraSweet) Artificial ingredients; has raised some health concerns 

Sucralose: (Splenda) Artificial ingredients, largely not broken down by the body

Honey: About equal parts fructose and glucose, plus antioxidants and small amounts of vitamins and minerals

Agave nectar: Derived from cactus and sweeter than sugar, but also contains more fructose

Saccharin: (Sweet’N Low) Oldest artificial sweetener; 400 times sweeter than sugar

The results suggest that eating fructose may not produce the same satiety effects as glucose. “Fructose is mainly metabolized in the liver and doesn't stimulate hormones, like insulin, that let the brain know that you're full,” Page says. 

So since fruits are high fructose, does this study mean we should eat less of them? "No,” insists Page. “It is important to note that while most whole fruits contain both fructose and glucose, they are also packed with fiber, which delays the absorption of sugar and helps us feel full”

She adds: “The amount of fructose that we get from whole fruit and vegetables is relatively small compared to the amount of fructose found in foods and beverages with added sugar sweeteners, like agave and high fructose corn syrup.”