Serge AhmedNobel Conference 61

Serge Ahmed

Research Director at Centre National de la Recherche Scientifique

Sugar: A Highly Addictive Fuel

When given a choice between cocaine and sugar water, laboratory rats consistently choose the sweeter option. Two decades ago, this finding, along with the notion that sugar could be addictive, was dismissed by much of the addiction neuroscience community. Addiction researchers were focused on drugs of abuse–alcohol, and tobacco–and they viewed food-related behaviors through a completely different lens. To many addiction researchers, the idea that a naturally occurring substance like sugar could hijack the brain's reward systems in ways similar to cocaine or heroin seemed absurd.

It was in this skeptical environment that Serge Ahmed began asking the questions that would fundamentally challenge our understanding of reward, pleasure and addiction in the human brain. What began as a systematic investigation into drug addiction led to the discovery that rats will choose sugar over cocaine. This finding led down unexpected paths that challenged established paradigms in addiction research, eventually paving the way to an entirely new avenue of research into the nature of reward and addiction. His approach is notably unique in the field; as he puts it, "I don't have fixed ideas about addiction. I do research: I remain open… but I don't settle on a definitive idea that I'll then defend tooth and nail." 

Serge Ahmed’s research reveals how sugar hijacks the same neural circuits that respond to addictive substances. His research suggests that the power of sugar over our behavior isn't simply about lack of willpower—it's about fundamental neural mechanisms that have evolved over millions of years. These findings bridge the gap between addiction science and nutrition, challenging us to reconsider the very nature of addiction itself.

Ahmed's research extends beyond the laboratory, reaching into the realm of public health policy and societal implications. His work suggests that our modern food environment, with its abundance of sugar-rich options, may be fundamentally misaligned with our brain's evolved reward systems. This understanding has profound implications for how we approach everything from school lunch programs to food industry regulations, bridging the gap between addiction science and nutrition and offering new perspectives on why we struggle with dietary changes despite knowing their importance for our health. 

Throughout his decades of research, Ahmed has remained remarkably self-critical and thoughtful about the limitations and possibilities of his work. Modeling human phenomena such as addiction in animals is intrinsically challenging, as there are uniquely human aspects of addiction that cannot be fully captured in animal models. Despite this, Ahmed has continued to approach this challenge with curiosity–as he himself has said that “as we better understand the animal…[we can] better understand ourselves." He approaches this complex field with remarkable humility, often using the metaphor of blind men touching different parts of an elephant to describe how different disciplines approach addiction – each one touching a piece of the truth, but none able to see the whole picture.

Serge Ahmed serves as Research Director at Centre National de la Recherche Scientifique (CNRS) and is the head of the “Choice, Addiction and Neurodysfunctions” team at the Bordeaux Neurocampus, where his research continues to unravel the complex relationship between sugar, pleasure, and addiction in the brain. He holds a PhD in Neurosciences & Pharmacology from the University of Bordeaux. 

His talk: In the mid-19th century, in his famous Treatise on Modern Excitants, the French novelist Honoré de Balzac already classified sugar alongside alcohol and tobacco. Today, the addictive potential and dangers of alcohol and tobacco are well established. What about sugar? We know that prolonged overconsumption of sugar is harmful to health, but to what extent can we identify sugar as a drug and its overconsumption as an addiction? And how can we reconcile this notion with everything we know about sugar as a vital fuel? In his presentation, Ahmed will describe the path taken by science since Balzac, emphasizing the questions and challenges posed by the extension of the concepts of drugs and addiction to sugar and, more generally, to so-called hyper-palatable foods.