It will come as no surprise that, on a whole, we’re eating too much sugar. Now, scientists have found that when our sweet tooth is sated, that craving is dialed down and in its place comes a sudden desire for fatty foods, which can wreak havoc on metabolic functions and weight.
Researchers at Umeå University in Sweden have identified a hormonal mechanism triggered by overconsumption of sugar, resulting in cravings for food high in fat. In a study on fruit flies (Drosophila melanogaster), sugar consumption swiftly signaled to the endocrine system that it should put the call out for some fat to avoid what it perceives as malnutrition.
“Too much sugar reduces sweet cravings but amps up fat intake, and vice versa,” explained co-author Mattias Alenius, Professor in the Department of Molecular Biology. “This ensures flies get enough sugar and fat as nutrients.”
In 2022, the team identified how even a slight increase in sugar intake induces the secretion of the Hedgehog (Hh) hormone. And while circulating Hh helped suppress sweet taste perception and preference, it greatly enhanced fatty acid receptors.
In this study, the scientists found that too much fat induced the adipose tissue secretion of Upd2, the equivalent of leptin in humans, into the fly’s ‘bloodstream’, its hemolymph. This resulted in the suppression of fat taste perception, and in its place a rise in the craving of sugary foods.
This mutual regulation suggests that overindulgence with either sugar or fat will signal to the required hormones that there’s a deficit of the other substance that needs urgent balancing.
“It's a tug of war between sugar and fat – not a restriction of total calories, as we would prefer,” said Alenius. “Presumably, humans have similar compensation mechanisms to flies, which means that we prefer to have as much fat as sugar. An American cheesecake is usually said to be the best way to drive our desire to eat.”
The researchers intend to adapt the study to human subjects, expecting a similar response to that of the fly’s hormonal triggers.
“We humans perceive fat as a taste, and it remains to be seen if these research findings apply also to us," Aleniu added. "Food for thought in further research.”
The study was published in the journal Cell Reports.
Source: Umeå University