Glucose and Fructose Satiate the Brain Differently

How insulin, GLP-1, and ghrelin affects the brain and behaviour

The modern Western diet is high in fructose, not from fruits but table sugar and high-fructose corn syrup. Previously in “Can Swapping Fructose for Starch Improve Metabolic Health?”, I discussed how excessive fructose impairs overall metabolic health, which can be reversed by replacing it with glucose or starch like bread or rice. Even in nature, fructose is the primary means by which animals store fat to prepare for food shortages.

That’s the body metabolism on glucose vs fructose. Herein this article would be about the brain on glucose vs fructose.

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Brain and Behaviour on Glucose vs Fructose

In 2015, researchers at the University of Southern California gave healthy, non-dieting adults either glucose- or fructose-sweetened beverage. In comparison to glucose, those who drank fructose displayed higher activity in the visual cortex when viewing food images in the fMRI machine. This enhanced visual responsiveness reflects a stronger motivation for food.

At baseline, hormonal levels and appetite ratings were the same. After drinking fructose, participants had a lower rise in plasma insulin than those who drank glucose. “Ingestion of fructose versus glucose also led to greater hunger and desire for food and a greater willingness to give up long-term monetary rewards to obtain immediate high-calorie foods,” the authors wrote.

• In another 2013 brain imaging study, those who drank fructose had lower circulating insulin and glucagon-like peptide 1 (GLP-1) levels. This was accompanied by less functional connectivity in the hypothalamic-striatal brain network that regulates satiety and reward. The comparative group was glucose drinkers.
• Similarly, in a 2011 study, healthy adults consuming glucose had higher levels of insulin and activities in cortical brain areas important for behavioural control. The opposite effects were seen in the fructose group, wherein their brain cortex involved in self-control was less activated.
• Again, a 2018 research showed that glucose consumption raised insulin and deactivated the hypothalamus — a brain region…