Some of the same brain mechanisms that fuel drug addiction in humans accompany the emergence of compulsive eating behaviors and the development of obesity in animals, according to research funded by the National Institute on Drug Abuse (NIDA), a component of the National Institutes of Health.

The study, conducted by researchers at the Scripps Research Institute, was released on March 28th in the online version of Nature Neuroscience and will also appear in the journal’s May 2010 print issue. When investigators gave rats access to varying levels of high-fat foods, they found unrestricted availability alone can trigger addiction-like responses in the brain, leading to compulsive eating behaviors and the onset of obesity.

“Drug addiction and obesity are two of the most challenging health problems in the United States,” said Dr. Nora D. Volkow, director of NIDA. “This research opens the door for us to apply some of the knowledge we have gathered about drug addiction to the study of overeating and obesity.”

Both obesity and drug addiction have been linked to a dysfunction in the brain’s reward system. In both cases overconsumption can trigger a gradual increase in the reward threshold — requiring more and more palatable high fat food or reinforcing drug to satisfy the craving over time.

The National Institutes of Health is launching a $37 million program that will use findings from basic research on human behavior to develop more effective interventions to reduce obesity. The program, Translating Basic Behavioral and Social Science Discoveries into Interventions to Reduce Obesity, will fund interdisciplinary teams of researchers at seven research sites. Investigators will conduct experimental research, formative research to increase understanding of populations being studied, small studies known as proof of concept trials, and pilot and feasibility studies to identify promising new avenues for encouraging behaviors that prevent or treat obesity.

The Washington Post published a story late last week about obesity in the United States. The story discussed the results of a new study by the Centers for Disease Control and Prevention (CDC). Here’s the article’s opening statement:

The obesity epidemic that has been spreading for more than a quarter-century in the United States has leveled off among women and may have hit a plateau for men …

I was surprised that they use the term “spreading”, since the article fails to mention any of the recent research pertaining to the spread of obesity through social networks.

The CDC study, titled “Obesity Among Adults in the United States — No Change Since 2003 — 2004″, found that there was no significant increase in the prevalence of obesity between 2003 — 2004 and 2005 — 2006 in the United States [1]. Obesity is defined as a body mass index (BMI, weight in kilograms divided by height in meters squared) of 30 or higher. In terms of height and weight, that equates to:

You can use the tools at the CDC website to determine your own BMI.

For 2005 — 2006, obesity prevalence was 33.3% in men and 35.3% for women. However, the prevalence of obesity doesn’t present a complete picture of weight trends among U.S. adults. By comparing the distribution of body mass index in 1976 — 1980 and 2005 — 2006 for adults 20 — 74 years of age, the data indicates that the entire adult population is heavier. Those adults heaviest have become heavier since 1980. Non-Hispanic black and Mexican-American women were more likely to be obese than white women. Among men, the prevalence of obesity did not differ significantly by race or ethnic group.

To see how obesity rates have increased over the past 20 years, check out the CDC’s animated map of U.S. obesity trends.

In a press release, Janet Collins, director of CDC’s National Center for Chronic Disease Prevention and Health Promotion, said [2]:

In view of these alarmingly high rates of obesity in all population groups, CDC has made the prevention of obesity one of its top public health priorities.

Indeed, since the publication of The Surgeon General’s Call to Action to Prevent and Decrease Overweight and Obesity in 2001, the CDC has taken the lead on many of the Department of Health and Human Services initiatives and programs [3]. The programs include communication and education efforts; interventions in nutrition, physical activity, and fitness; disease surveillance; research; clinical preventive services and therapeutics; and policy and Web-based tools. They target populations at all life stages, including infants, breastfeeding mothers, and children and adolescents.

Being overweight or obese increases the risk of many diseases, including [4]:

• Hypertension
• Type 2 diabetes
• Coronary heart disease
• Stroke
• Osteoarthritis
• Breast, colon and endometrial cancer

Individual behaviors, environmental factors and genetics all have an effect in causing people to become obese. The choices individuals make with respect to the foods they eat and their physical activity can also contribute to obesity. The CDC offers a number of nutrition resources to help people start healthier eating habits.

I’ve written previously about the so-called obesity epidemic in children and the results of a number of studies identifying a connection between food consumption patterns and television advertising. To my knowledge, no study to date has evaluated the effect of television advertising and food consumption on adults.

References

1. Ogden et al. Obesity among adults in the United States–no change since 2003–2004. NCHS data brief no 1. Hyattsville, MD: National Center for Health Statistics. 2007 Nov.
2. New CDC Study Finds No Increase in Obesity Among Adults; But Levels Still High. National Center for Health Statistics News Release. 2007 Nov 28.
3. Gerberding and Marks. Making America fit and trim–steps big and small. Am J Public Health. 2004 Sep;94(9):1478-9.
   View abstract
4. Overweight and Obesity. Department of Health and Human Services Centers for Disease Control and Prevention. Page updated on Nov. 17, 2007.

On Saturday afternoon, September 29th, 2007, the cable television channel Nickelodeon showed nothing for three hours to celebrate “Worldwide Day of Play”, encouraging children to get off the couch and be active. The “Worldwide Day of Play” is part of Nickelodeon’s “Let’s Just Play” campaign, in partner with the Alliance for a Healthier Generation, to encourage kids to participate in active, healthy and playful lifestyles. The goal of the Alliance for a Healthier Generation is to create a new generation of healthy Americans by addressing one of the nation’s leading public health threats — childhood obesity.

So it should be simple, right? Don’t let kids spend so much time in front of the television … get them to be more active and they won’t be overweight. Or is there more to it? Let’s explore some of the science.
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