High-fructose corn syrup has found its way as a sweetener into just about every processed food you’ll find in the grocery store, from pasta sauce and soft drinks to premade meals. But as waistlines have grown, attention has turned to this sugar as a possible culprit for the health problems that face the U.S. population. A new study out this week investigated how fructose might affect your brain in ways other types of sugar don’t and found that fructose might be making it harder to stick to your long-term diet goals in the face of tempting food items.
What is fructose?
Sugar comes in a variety of different forms. Most of the sugar we eat comes in the form of glucose or fructose, which are two naturally occurring sugars found in the foods we eat. Both glucose and fructose are also building blocks. They’re not made up of other types of sugar molecules, but they can be combined to form other sugars. Table sugar, which is technically called sucrose, is made up of a fructose and a glucose sugar linked together. Lactose, which is found in milk, is made up of a glucose and galactose, another sugar building block. When linked together, these building blocks can be used to do more than just sweeten food. Dietary fiber, for example, is a long chain of a certain type of sugar that’s linked in a way that makes it hard for us to digest. That’s why fiber helps keep you regular rather than making you gain weight. Fructose is just one form of sugar among the many we consume every day.
How does the body handle fructose?
When sugars enter the intestines, they’re broken down into smaller forms that can be easily absorbed. Once broken down into building blocks like glucose and fructose, the sugars are absorbed directly into the bloodstream. From the intestines, these make their way to organs that either use them for energy or store them for later needs.
But because these sugars have slightly different structures, the body uses them in slightly different ways. The tools used to turn glucose into energy don’t work the same way on fructose. Importantly, fructose can bypass some of the steps the body normally uses to control how fast energy is burned. Fructose also doesn’t trigger the release of insulin, a hormone that helps keep your blood sugar within the normal range and helps control your appetite. Finally, some studies have found that fructose changes the appetite controls in the brain in a way other sugars don’t. All of these differences have made researchers suspicious that fructose might be acting in a way that encourages health problems.
What did this study want to test?
The researchers wanted to figure out if fructose might change a person’s eating habits and decisions about food. They wanted to compare fructose against glucose because both are common in most diets, but fructose has increased in the American diet over the last several decades and has been associated with certain health issues. The goal was to see if some of the different effects that fructose has on the brain might explain health problems like obesity.
How did the researchers test this?
The team recruited 24 healthy young men and women. Each was given a cherry-flavored drink sweetened with either glucose or fructose. They then went into an MRI scanner and were asked to rate how hungry they felt and how much they wanted a variety of different foods. They were then shown pictures of decadent foods and were asked to choose between having the food or getting a large sum of money. If they chose the food, they could have it right then. If they chose the money, they’d have to wait for a month before they received it. The researchers also drew blood before and after the trial to see how each participant’s body responded to the sugar. After several days, the experiment was repeated, but each participant was given the other form of sugar.
What did the researchers find?
The results showed that fructose boosted the appeal of seeing food. A dose of fructose made the participants feel hungrier, wanting food more than when they consumed glucose. They also found that people were more likely to go for the immediate satisfaction of decadent food over money when they ate fructose. Finally, their body released less insulin when fructose was around, indicating that the body wasn’t acting to try and keep blood levels low the way it normally would with glucose. Insulin also acts on the brain to help control hunger and appetite and the researchers think that lower levels may explain why fructose did little to help people feel less hungry.
How does this affect me?
This research shows that fructose, especially when it’s found in sugary drinks, is changing the way you think about food. It could be boosting your appetite and may make unhealthy foods more appealing. All of this can contribute to diseases like obesity and diabetes. But more than that, this study shows that fructose changes the way you think about short-term payoffs and long-term goals. Fructose makes you want the short-term reward more than the long-term. That means that your brain on fructose might be more likely to pick that extra brownie even when you know it undercuts your efforts to lose weight.