It appears that deciding to eat a second slice of cake or to finish a bag of candy may not be entirely up to us, as sugar cravings may be linked to a liver hormone, according to a study made at various universities. This link may extend to alcohol consumption as well, not being limited to just having a sweet tooth.
This finding was made by two independent teams from the University of Iowa and the University of Copenhagen. Both of these used genetic studies as well as careful observation on the behavioral patterns of mice and monkeys.
The liver hormone in question is the fibroblast growth factor 21, FGF21, that gets released into the brain in accordance with sugar and carbohydrate intake. It acts specifically on the PVN in the Hypothalamus, and its pathways are linked to sugar intake suppression.
Although several neural pathways have been linked to sugar and alcohol consumption, the FGF21 is the first of its kind, being the first liver-derived hormone that gets affected by this type of nutrient intake. What is also interesting is that this hormone is extremely potent in suppressing appetite, with only a does of it completely stopping a monkey from craving sugar water.
Because of the apparent link between FGF21 and appetite control, scientists are currently attempting to see if other hormones can be linked with protein and fat consumption as well, not just carbohydrates. A factor that may hinder this research is the fact that further inquiries have to be made in order to see if the reward system for sugar intake, linked to the liver hormone, can influence depression, mood swings, and other behavioral patterns.
One of the reasons why the liver produces this hormone could be that FGF21 protects the organ from excessive alcohol consumption that can greatly damage it, because ethanol is derived from sugar. The effects of the hormone can also be seen at a macronutrient level, in accordance with a study from 1965.
Another interesting result from this study was that the liver does not differentiate entirely between natural sugars and artificial ones, producing the same hormone. This helps researchers better understand how the whole system regulates diet preferences, leading some parties to believe that our diet choice is not entirely up to us.
One has to take into account that us humans also link certain foods with previous experiences. For example, if you had sugar as a child in the form of cookies after doing something good, this creates a neural link, changing your behavior in the later stages of your life accordingly.
This hormone linkage will eventually lead to commercialized medication that can effectively quell one’s sugar craving or thirst for alcohol. But extensive clinical studies and research have to be conducted in order to achieve this goal, a fact acknowledged by both independent parties.
Even if sugar cravings may be linked to a liver hormone, with the FGF21 currently being under clinical trials for treating type 2 diabetes and obesity, the hormone’s link to human reward behavior needs to be further inquired upon. In previous studies, the same hormone was linked to metabolism changes, weight loss, female reproduction and circadian loss as well.