In a recent study, published in the journal Nature Metabolism, scientists from Trinity College Dublin and Princeton and Harvard Medical School share new research into natural appetite control, which offers promise in the battle against obesity and type 2 diabetes.

The scientists report new insights into how the widely used diabetes drug metformin benefits patients with type 2 diabetes. Metformin is described by some as a “wonder drug” even though we still do not know exactly how it works.

This study shows that metformin increases the amount of an appetite suppressing factor called lactoyl-phenylalanine (lac-phe), identified in 2022 as a natural appetite suppressant, and which is known to be raised by vigorous exercise. 

The scientists probed data from other studies involving large numbers of patients, to conclusively demonstrate that lac-phe levels rise after individuals take metformin. This work opens a new avenue for developing targeted anti-obesity treatments. 

Barry Scott, first author of the research and PhD candidate in TCD’s School of Biochemistry and Immunology said: “I’m hopeful our research can have a big impact. Metformin is the most prescribed drug for type 2 diabetes, and it’s very safe and well tolerated. How metformin affects appetite was not known, but this work shows that its influence on lac-phe is a key part of its hunger suppressing impact.” 

The team also discovered that lac-phe increases after eating, and so contributes to the feeling of fullness after a meal.  

Prof David Finlay, associate professor in immunometabolism at TCD, who co-supervised the work with Prof Lydia Lynch, Princeton and Harvard Medical School, said: “Our study shows that the type of food you eat matters. For instance, eating sugar-rich date fruits caused an immediate and large surge in lac-phe, whereas drinking a sugar-rich drink did not. This could help explain why liquid calories can drive obesity.”

Prof Lynch said: “Identifying the factors that control appetite and satiety after a meal is important to help us to understand and ultimately treat the current obesity epidemic. Further understanding lac-phe’s actions may lead to a new class of safe and effective anti-obesity drugs.”

This research was supported by Science Foundation Ireland and the National Institutes of Health in the US.