Someone who binge eats consumes an objectively large amount of food while feeling a loss of control over eating. When episodes occur weekly for several months, the action moves into the realm of binge eating disorder. So how does this type of eating affect obese individuals with Type 2 diabetes who are actively working to lose weight?

According to new findings from a Penn researcher published in the journal Obesity, it presents a significant obstacle: Those who continue to binge eat while trying to lose weight drop about half as much weight as those who don’t binge eat, or those who do and then subsequently stop.

“Continued binge eating can act as a major roadblock,” says Ariana Chao, an assistant professor in the School of Nursing and a faculty member in the Center for Weight and Eating Disorders in the Perelman School of Medicine.

Chao studies addictive-like eating behaviors, including how they influence the effectiveness of treatment for different populations. To better understand the role of binge eating in weight loss, she and colleagues from Penn Medicine, the Children’s Hospital of Philadelphia, the University of Connecticut, and the National Institute of Diabetes and Digestive and Kidney Diseases assessed data from the National Institutes of Health’s Action for Health in Diabetes, or Look AHEAD, study, a multi-center randomized controlled trial of more than 5,000 participants ages 45 to 76, all with a body mass index above 25 (or 27 for those using insulin) and Type 2 diabetes.

The parent study compared the effects on cardiovascular morbidity and mortality of an intensive lifestyle intervention to diabetes support and education. The former included dietary recommendations, physical activity, and behavior modifications; those in the diabetes support and education group were encouraged to attend three sessions per year, one each about physical activity, social support, and eating.

In addition, Look AHEAD annually assessed binge eating via a questionnaire that recorded any intake of excess food coupled with a feeling of lack of control during the past six months, and asked participants about any “compensatory behavior,” such as vomiting or excessive exercise.

In this study, Chao and her team analyzed the impact of binge eating on weight loss. The researchers found that at four years, participants who reported no binge eating or a reduced tendency to do so lost more weight than those who continued to binge eat. Participants lost 4.6 percent of initial body weight compared to 1.9 percent, respectively.

“Previously, it was unclear whether people who binge eat need to be treated for that behavior before attempting behavioral weight loss, or whether they’ll do OK in behavioral weight loss without it,” says Chao, who has a secondary appointment in Penn Medicine’s Department of Psychiatry. “Our findings suggest that people who continue to binge eat after they start a behavioral weight-loss program need an additional treatment like cognitive behavioral therapy, which is one of the most effective treatments for binge eating.”

Such treatment includes work to recognize how thoughts, feelings, and behaviors are intertwined. For instance, Chao says, if someone eats to cope with stress, cognitive behavioral therapy could aim to untangle why and how to change the behavior.

Though this study looked at a particular subset of people, two-thirds of the adult population in the United States are either overweight or obese. For that reason, Chao says it is important for clinicians to start screening more patients for these behaviors, and to refer them for additional treatment.

She also acknowledges some limitations to the dataset. For example, an eating disorder diagnosed through an extensive interview between patient and clinician is more reliable than one that comes via self-report questionnaires, as in Look AHEAD. Either way, there is more to learn about the connection between binge eating and weight loss.

“Individuals with a history of binge eating shouldn’t be excluded or discouraged from engaging in behavioral weight loss,” says Tom Wadden, the Albert J. Stunkard Professor of Psychology in Psychiatry in the School of Arts & Sciences and director emeritus of the Center for Weight and Eating Disorders, who was also involved in the study. “But binge eating should be monitored regularly during weight loss. Participants who continue to report this may benefit from additional or more targeted treatment to ensure success.”