Some People Have a Sweet Brain, Scientists Find

Many of us blame our cravings for sweet, sugary treats on our "sweet tooth," but we should be placing the blame on our sweet brain.

Those with this kind of brain may also be more likely to gain weight over time. Now, researchers have suggested a neural mechanism is behind these associations.

"There are lots of factors that may influence sweet taste preferences, including genes, age, gender, long-term food intake, disease status," said Kathleen Page, an associate professor of medicine and co-author of a study at the Keck School of Medicine at the University of Southern California

"Collectively, evidence suggests that the origins of a sweet tooth derive from both genetic and environmental components," Page told Newsweek.

She went on: "Studies have shown that repeated exposures to sweets can modify food preferences, which suggests an important role of the environment. [Other] large, genome-wide association studies have shown that specific genes are associated with a high preference for sweet flavors, and these same genes are linked to higher sugar consumption. Interestingly, some of these genes are highly expressed in the brain."

In a recent study published in the journal Physiology and Behavior, Page and her team demonstrated that a preference for sweeter foods was associated with an increase in activation in the hypothalamus—a part of the brain involved in appetite control—in response to glucose.

To explore these effects, 54 participants aged 18 to 35 were asked to undergo brain scans before and after consuming a sugary drink. They were also asked to taste sugar solutions of varying concentrations and rate them depending on their taste preference. Those who preferred the more concentrated sugar solutions had greater activation in the hypothalamus after consuming sugary drinks.

The weights of the participants were measured over a year, and those with a sweet taste preference were more likely to gain weight over the study period.

So how does this work? Previous studies have shown that appetite-associated regions of the hypothalamus become deactivated in response to the ingestion of glucose (i.e., sugar). This deactivation is often considered to be a marker of satiety, or feeling full. In addition, fMRI studies have shown that people who do not experience this marked reduction in hypothalamic activity after eating are often at higher risk of obesity and Type 2 diabetes.

The hypothalamus is home to several sweet-taste brain receptors, which may also be involved in mediating this hypothalamic brain activation. So it's all connected—your preference for sweetness is linked to how your brain reacts to eating and perhaps how well your body signals satiety.

"It's well known that taste plays a key role in food choices," Page said. "A high preference for sweets may affect long-term eating patterns and health outcomes, including obesity risk. Understanding potential mechanisms that underlie individual differences in sweet taste preferences and its link to weight gain may help lead the way to precision-based nutrition recommendations to improve health outcomes."

While your sweet tooth may be partially hardwired, your environment is also partly to blame. In other words, there are things you can do to curb your cravings.

"The substantial increases in sugar and high-intensity, non-nutritive sweetener consumption over the last few decades are likely affecting sweet taste preferences, food choices and risks for weight gain," Page said.

The best way to quell your sugar cravings is to eat regular meals with high protein and fiber to promote fullness and reduce snacking. Switching to naturally occurring sugars, like those in fruits and vegetables, can also help satisfy your sweet tooth without dosing up on energy-dense "free sugar."