Michael Lowe, Ph.D.
Professor of Psychology
Research Description
My research involves studying eating and weight regulation - and eating and weight disorders - from the perspective of clinical psychology, nutritional science, psychobiology, and neuroscience. The following describes five general areas in which my research group has been exploring these domains. Within each area, clicking on one of the blue numbers will take you to one of our publications.
Research Areas:
- The relationship between dieting, overeating, and weight control
- Obesity and the prevention of weight gain and weight regain
- Eating disorders research
- Integrating biological and psychological perspectives on eating and weight regulation
- Research on the "power of food"
1. The relationship between dieting, overeating and weight control
I have a long-standing interest in the relationship between dieting, overeating and body weight (Lowe, 1993 (17), 2003 (13); Lowe and Levine, 2005 (9)). My work has questioned the theory that restrained eating or dieting is a major cause of overeating and weight gain (Lowe, 1993 (17); Lowe & Timko, 2004 (10); Lowe & Levine, 2005 (9); Stice et al., 2004 (12), Stice et al., 2007 (1)). Our work suggests that, especially in an obesity-promoting environment like our own, certain people who are most responsive to palatable foods will tend to over-consume calories and gain weight. Given our society's emphasis on thinness and fitness, such individuals are likely to restrict their eating and be labeled "restrained eaters" or “dieters”. From this perspective restrained eating and dieting are responses to, rather than a cause of, overeating and weight gain. One implication of this work is that, to achieve long-term weight control, it may be more effective to modify food environments (at home, in cafeterias, etc.) than to modify people's beliefs and skills (Lowe, 2003 (13)). Another implication is that the widespread practice of restrained eating is typically aimed at trying to avoid overeating the palatable foods that constantly surround us, not at losing weight to achieve a culturally-prescribed thin body (Lowe & Levine, 2005 (9); Lowe & Butryn, 2007 (4); Stice et al., 2007(1).
2. Obesity and the prevention of weight gain and weight regain
As just noted, it appears that dieting does not usually cause eating problems or weight gain. On the other hand, however, its beneficial effects usually do not last (Lowe & Timko, 2004 (10). It is crucial to develop more effective ways of limiting energy intake in an environment where there are unlimited opportunities for eating (Lowe, 2003 (13)). In the past 8 years we have received four NIH funded grants to specifically study the prevention of weight gain and, after a weight loss, the prevention of weight regain. The first grant, the results of which have recently been written up for publication, involved a significant departure from the traditional "lifestyle change" approach for prevention of weight regain by concentrating on reducing the energy density (the number of calories per gram of food consumed) of participants' long-term diets. The results of this study suggest that focusing on reducing the energy density of the diet is a promising way of improving weight loss maintenance.
The second grantexamined long-term modifications to worksite cafeterias to improving nutritional intake and prevent weight gain among patrons. We collaborated on this grant with the Sodexo Corporation, one of the largest providers of food services in the world. We developed a computerized system whereby food purchases of study participants could be automatically tracked on a daily basis. Over a six month period the intervention produced significant reductions in caloric intake during lunch and a significant reduction in the percentage of calories from fat.
The third grant is an ongoing 5-year study examining ways of preventing weight regain following weight loss. Participants are overweight patients referred from primary care practices. This project tests two different nutritional strategies (increasing structured eating, and lowering the caloric density of the diet) in order to avoid or minimize weight regain after weight loss.
The final grant in this category focuses on prevention of weight gain in female college freshmen. This study, which is being carried out at both Drexel and the University of Pennsylvania, targets students vulnerable to weight gain. It utilizes group interventions to capitalize on the motivational power of groups. The content of the groups is aimed at modifying participants' food choices and food environments (Lowe, 2003; Lowe et al., 2006 (5)). We are currently in the third year of this 5-year grant.
We have NIMH funding to explore treatment development for eating disordered patients. This project is being carried out at the Renfrew Center for eating disorders in Philadelphia, and is testing the effectiveness of a cognitive-behavioral intervention for eating disorders among patients at two of Renfrew's intensive outpatient treatment centers.
Our collaboration with the Renfrew Center has spanned 14 years, and has led to the collection of a great deal of data, some of which has been published (Lowe et al., 1996, 1998; Lowe et al., Eating Behaviors, 2003; Gleaves et al., 2000) . During the past two years, my role in the research enterprise at Renfrew has significantly expanded, as I have assumed the role of Senior Research Consultant as well as serving as a member of the Research Steering Committee. Through this relationship, the Renfrew Center is in the process of fundamentally reorganizing their research department, greatly extending the scope of the research they do, and improving their patient assessment procedures. This newfound ability to collect data on large numbers of eating disorder patients in a short period of time should be quite advantageous since such capabilities are not available elsewhere.
I have been conducting research investigating the role of dieting in bulimia nervosa for the past 10 years (Butryn et al., 2006 (7); Gleaves et al., 2000 (14); Lowe et al., 1996 (16); Lowe et al., 1998 (15); Safer et al., 2004 (11); Lowe et al., 2006 (6); Lowe et al., 2008 (2)). My research on dieting and eating disorders has raised questions about the prevailing research models of the dieting-binge eating relationship that could result in fundamental changes in the cognitive-behavioral model of bulimia nervosa and its treatment. Data supporting our model suggests that significant past weight loss - or weight suppression - plays a major role in the development and maintenance of the disorder (Butryn et al., 2006 (7); Lowe et al., 2006 (6); Lowe et al., IJED, 2007 (2)). We are beginning pilot data collection at Renfrew to support a new grant we will be submitting to further develop this new model of bulimia and to test a new treatment approach consistent with this model.
4. Integrating biological and psychological influences on eating and weight regulation
In the past several years I have become increasingly involved in research to understand how biological and psychological factors combine to influence eating disorders and obesity. One such effort has involved differentiating between homeostatic and hedonic eating motives and describing the implications of this distinction for the wisdom of dieting (Lowe & Butryn, 2007 (4); Lowe & Levine, 2005 (9)). A second focus is understanding how behavioral and metabolic aspects of restrained eating combine to produce a predisposition toward weight gain in restrained eaters (Lowe & Kral, 2006 (8)). A third set of studies is examining neurophysiological correlates of both restrained eating and binge eating using fMRI and EEG.
5. Research on the "power of food"
To better understand the predisposition that may make some people more susceptible to food-related temptations, my research team has developed a new measure of the psychological impact of the food environment called the Power of Food Scale (PFS). There are a number of existing measures that assess restrained eating or overeating induced by various emotional or social stimuli, but there is no measure of individual differences in the psychological impact of an obesogenic environment.
In a study conducted collaboratively with two other Drexel faculty members (Evan Forman and James Herbert) the PFS was found to predict individual differences in chocolate cravings and also moderated the effects of treatment on cravings. That is, the treatment that worked best to reduce cravings depended on subjects' PFS scores (Forman et al., 2007 (3)).
A third study conducted by a Ph.D. student (Chris Ochner) used EEG to explore the activation of the prefrontal cortex in obese individuals. We studied level of activation in the left and right prefrontal cortex because other research has shown that a predominance of left-to-right prefrontal activation is associated with the strength of an individual's tendency to be motivated by the pursuit of rewards as opposed to the avoidance of negative stimuli. We studied three individual differences measures and found that the PFS was significantly related to level of left-to-right asymmetrical activation.
A fourth study, based on the dissertation of Maria Coletta, Ph.D., used functional neuroimaging to compare brain activation of restrained and unrestrained eaters in response to foods moderate or high in palatability. The results of this study suggest that, when fasted, restrained eaters do not experience hunger in the same way as unrestrained eaters and, when fed, find palatable foods highly appealing despite having eaten a meal recently.