Posted by Miriam Gordon on August 29, 2008
In the 1995 film “The Basketball Diaries”, Leonardo DiCaprio brilliantly portrays Jim Caroll’s descent into heroin addiction. When I attempt to explain to people who do not suffer from obesity what complete, sudden withdrawal from refined carbohydrates is like, based on my own experience, I get a mental picture of what DiCaprio’s Jim Carroll goes through as he suffers the torture of withdrawal from heroin. Although this is an extreme example, withdrawal resulting from completely eliminating refined carbohydrates or other binge foods from one’s diet is more than a matter of putting up with a migraine, insomnia, or general feelings of malaise, although all of these symptoms may result. Kay Sheppard, the author of “Food Addiction – The Body Knows”, explains that the food addict is compelled, as if by knife point, to acquire and devour binge food, and that only complete abstinence from refined flour, sugar and wheat can arrest the addiction. It is Kay Sheppard’s food plan that helped me, twice, to lose 60 lbs. and keep most of it off for 5 years. I was able to do this only with the help of Overeaters Anonymous and the most wonderful sponsor I could ever have hoped for. Unfortunately, she became too ill to continue as my sponsor. I have since fallen off the wagon again, and have regained those 60 lbs. for a third time.
Long considered a joke in contemporary western society, the idea of biologically based addiction to refined carbohydrates and other “addictive” foods is finally gaining a foothold in high quality scientific data. Bartley Hoebel’s group at the Princeton University Department of Psychology has published a series of papers detailing their experiments on sugar addiction using an animal model originally established for studying opiate addiction. Nicole M. Avena is the lead author on several studies that provide some of the most compelling evidence yet of the biological mechanisms of addiction to sweets, and their similarity to the biological basis of opiate addiction.
In a recent review article, Nicole Avena, Pedro Rada, and Bartley Hoebel (Avena NM, Rada P, Hoebel BG. Evidence for sugar addiction: behavioral and neurochemical effects of intermittent, excessive sugar intake. Neurosci Biobehav Rev. 2008;32(1):20-39. Epub 2007 May 18.) explain why addiction to sugar shares the same basic neurochemical mechanisms that underlie opiate addiction. The first aspect of the theory is based on evolutionary mechanisms that motivated survival in an environment where food was scarce. Feelings of comfort in response to feeding were necessary to insure survival. The same brain mechanisms that are responsible for this feeling of comfort have been shown by many laboratories to underlie opiate addiction. They also cite circumstantial evidence from the testimony of many people that they are compelled to eat sugary foods in a way that is comparable to alcoholics who have overwhelming urges to drink. Also, with approximately 25-30% of United States citizens characterized as overweight or obese, along with the multi-million dollar diet and fitness industry, it is clear that many people put considerable effort into weight loss and yet fail to maintain the loss. Therefore, clearly, it is worth investigating the neurochemical mechanisms that are the basis of this seemingly addictive behavior.
Throughout this review article, terms that define addiction, including bingeing, withdrawal, craving and sensitization, are interwoven with scientific data from experiments with rats which have intermittent access to sugar solutions. When ingested, addictive drugs cause an increase in dopamine levels in an area of the brain called the nucleus accumbens. Hoebel’s group has found that same phenomenon in rats. Other changes in the nucleus accumbens, including decreased enkephalin gene expression are also seen both with opioids and sugar. And, as with other opiates and psychostimulants, withdrawal symptoms are observed when the rats are deprived of sugar. Another important series of observations show that as with addictive drugs, after becoming accustomed to having regular intermittent access to sugar each day and then being deprived of the sugar solution, the rats exhibit classic signs of withdrawal, including anxiety, depression, craving, and even “cross-sensitization” to other substances of abuse (substituting another addictive substance in the absence of the drug of choice).
After presenting and analyzing all the available data, Dr. Hoebel’s group concludes that in a rat model which has proven relevance to human addiction, intermittent access to a sugar solution followed by periodic deprivation results in most of the same molecular and behavioral changes associated with rats that become addicted to other drugs of abuse. What this group is proving on a neurochemical and behavioral level would not surprise many of us who have instinctively known “food addiction” for years.