Researchers at Umeå University call this hormonal interplay a “tug-of-war” between sugar and fat.
If you eat a lot of sugar, be careful with sweets: when sugar levels in the body rise, the urge for sugary treats often falls — but that drop is frequently replaced by a sudden craving for fatty foods. That switch can harm metabolic function and contribute to weight gain.
Sugar and Fat – A Dangerous Duo
The hormonal mechanism set off by excessive sugar intake, which then drives people toward high-fat foods, creates a vicious cycle. “An excess of sugar reduces the desire for sweets but increases the urge to eat fats, and vice versa,” explained study co-author Mattias Alenius, a professor in the Department of Molecular Biology.
The team confirmed this pattern through experiments on fruit flies (Drosophila melanogaster). After eating sugar, the flies’ endocrine systems quickly signaled a lack of fats. Without a dose of fatty food, the flies did not feel satiated, New Atlas reported.
Researchers found that sugar intake triggers secretion of the hormone Hh, which suppresses sweetness perception and boosts fatty-acid receptor activity. Conversely, a high intake of fat stimulates the hormone Upd2, which dampens the craving for fat and sparks a desire for sweets.
This mutual regulation suggests that excessive consumption of either sugar or fat sends hormonal signals that a different nutrient is lacking and needs to be balanced.
According to Professor Alenius, the situation is a tug-of-war between sugar and fat, rather than simply a matter of limiting overall calories.
“People likely have the same compensatory mechanisms as flies, which means our bodies prefer to maintain a balance of fat and sugar,” noted Mattias Alenius.
Fruit flies are common model organisms in genetic experiments. More than 60 percent of genetic diseases in humans share similarities with those in fruit flies, and Drosophila are used to model conditions such as Parkinson’s and Alzheimer’s. Researchers also study immune diseases, cancer, diabetes, and other mechanisms using Drosophila melanogaster.
The team plans to conduct a similar study in humans. The study’s findings were published in the journal Cell Reports.
