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“Because of the increasing rates of obesity, unhealthy eating habits, and physical inactivity, we may see the first generation that will have a shorter life expectancy than their parents.”

U.S. Surgeon General,
Richard Carmona,
March 2004


Jeffrey Grimm, Ph.D

2009 Summit video presentation

Associate Professor in the Psychology department at Western Washington
University and a member of the faculty in the Program in Behavioral Neuroscience, and Co-Director of the Northwest Center for Research on Eating Behaviors.


Jeff Grimm is an Associate Professor in the Psychology department at Western Washington University. He is also a member of the faculty in the Program in Behavioral Neuroscience at WWU and serves as Co-director of the Northwest Center for Research on Eating Behaviors. The NWCREB is a collaboration between Dr. Grimm and Dr. Dianne Lattemann at the University of Washington. Dr. Grimm received a Ph.D. in Experimental Psychology at Washington State University in 1999 with his dissertation focus on neural substrates of cue-induced relapse to cocaine craving in rats. From 1999-2001 he was a Research Fellow at the National Institute on Drug Abuse where he continued to examine drug craving. It was there that he identified with his colleagues the time-dependent increase in cocaine seeking during abstinence now referred to as incubation of craving. Incubation of craving for sucrose has now come to occupy most of his research program as a faculty member at WWU. As Co-director of the NWCREB, Dr. Grimm works with colleagues to conduct basic studies on the rewarding properties of foods and to provide educational outreach to the public to help people make science-informed choices in their diets.


Most people are well aware of how advertising and social situations can lead them to eat when they are not hungry. The effect of these environmental cues are a frustration for a healthy individual watching their weight, but for an obese individual they can serve as an overwhelming push to eat—further contributing to their disease.

It is now clear that there are several features of uncontrolled eating that resemble criteria for addiction to drugs as defined by the American Psychiatric Association. For example, addiction to drugs is characterized by intense craving and ensuing compulsive drug-seeking. Individuals that have trouble avoiding excessive food intake also experience intense craving and will focus their behaviors on acquiring food.

Along with colleagues at the National Institute on Drug Abuse and, more recently, at Western Washington University, I have observed key similarities between craving for drugs of abuse and sugar including similarities in the neural substrates of drug and sugar craving. Our first discovery was that rats in prolonged abstinence from cocaine self-administration will work harder pressing a lever for the presentation of a tone and light cue (no drug) that was previously paired with their cocaine compared to rats in very early abstinence.

We subsequently observed incubation of craving for sucrose. In these studies, rats had previously self-administered sucrose by drinking a drop of sucrose solution. As with the cocaine study, each delivery of sucrose depended on pressing a lever and each delivery was accompanied by a tone and light cue.

Incubation of sucrose craving is an extremely robust phenomenon. For example, we see this time-dependent increase in responding for a sucrose-paired cue even when the rats are tested multiple times. Modern learning theory would predict that repeated exposure to the testing condition would lead to a decrease in responding over time, otherwise known as extinction.

In addition, prolonged access to sucrose (“satiety”) up to the beginning of a test session was without effect at reducing incubation of sucrose craving. This finding supports a hypothesis that craving in response to sucrose-paired cues becomes dissociated in some way from sucrose itself. If this is true, it helps to explain how cues push food craving and associated seeking (and intake) even when the individual feels “full”.

Incubation of craving and obesity?

Incubation of sucrose craving has not yet been documented in humans. However, incubation of craving for cocaine, heroin, and cigarettes has been observed. Given the overlap between behavioral and neural substrates of drug and food craving, it is likely incubation of sucrose (and other food) craving occurs and has an important role in unhealthy eating behaviors.

The work in my laboratory is primarily focused on understanding the incubation of craving phenomenon. Our hope is that what we find in the laboratory can translate into therapeutic interventions for addictions, including unhealthy eating behaviors. This hope is reflected by the Mission of the Northwest Center for Research on Eating Behaviors (NWCREB) of which I am Co-director. The other Co-director is Dr. Dianne Lattemann at the Puget Sound VA and University of Washington Department of Psychiatry and Behavioral Sciences. NWCREB was created with two aims. First, we examine eating problems, primarily obesity, with basic research using animal models. Second, we take our findings to the public to help them understand how such findings can inform them on how to stay healthy in an “obesigenic” society.

For the first aim, our studies have ranged from examining how insulin and leptin affect the rewarding efficacy of sugar to how sugar can synergize with fat to make fat more rewarding. This second study was done in collaboration with one of the NWCREB panel advisors, Dr. David Kessler at the University of California San Francisco. Other basic research studies particular to my lab have been to further our understanding of possible “interventions” for incubation of sucrose craving. For example, we have found that incubation of sucrose craving can be attenuated by an opiate antagonist, and also by one month of environmental enrichment. Studies in progress are examining how taste aversion reduces incubation of sucrose craving. We have also conducted studies on the contribution of the neurotransmitter dopamine in “addiction-related” sites of the brain to the incubation of sucrose craving.

For our second aim, we have conducted outreach programs at the Pacific Science Center and at Garfield High School in Seattle. We look forward to adding web-based informational resources as we develop our new affiliation with the University of Washington Center for Public Health and Nutrition (UWCPHN). The UWCPHN is directed by Dr. Adam Drewnowski, another member of the advisory panel to the NWCREB.

From work in my laboratory and with the NWCREB I hope to contribute to a reduction in obesity rates. Understanding unhealthy eating behaviors in the context of addiction-related behaviors and brain circuitry provides a novel way to tackle the obesity epidemic.

Relevant Publications and Links


Environmental enrichment reduces sucrose craving

The milkshake study

Naloxone reduces sucrose craving

Sucrose craving is potentiated by cocaine

Leptin and Insulin and sucrose reward

Incubation of sucrose craving parametrics

Incubation of cocaine craving

Leptin and Insulin and sucrose reward.pdf

Incubation of sucrose craving parametrics.pdf

Incubation of cocaine craving.pdf