I have a long-standing interest in restrained eating and dieting. My work has led to the following conclusions. Researchers often study the monolithic construct of “restrained eating,” but my research has shown that there are three different types of food restriction that are associated with different psychological and biological profiles. The three types are food restriction to prevent weight gain, where the primary source of restraint comes from a preexisting disposition to weight gain; weight loss dieting, where an individual is trying to reduce their food intake in order to lose weight; and weight suppression, where an individual successfully loses weight and stays well below their highest past weight for some time. These distinctions have relevance to both eating disorders and obesity. (Relevant publications: (Lowe and Levine, 2005; Chen et al., 2021).

I have been conducting research investigating the role of both weight suppression (the discrepancy between one’s highest adult body weight and current weight) and current dieting (an ongoing effort to lose, or avoid gaining, weight) in bulimia nervosa for the past 20 years. This work has been supported by two NIMH grants over the past 10 years, one focusing on psychological and biological correlates of weight suppression and the other focusing on neurophysiological correlates of weight suppression.

There are now over 100 studies on the role of weight suppression in both eating disordered and non-disordered groups (for reviews, see Lowe et al., 2018; Juarascio et al., 2018; Lowe [AJCN commentary], 2021). We also recently created an alternative measure of weight suppression called developmental weight suppression. This developmental measure recognizes for the first time that if highest premorbid weight was reached before the age of 21 (which is the case for many with disordered eating), it should be measured as z-BMI, based on the age and height at which the past highest weight was reached. Details of the new developmental measure are available here (Singh et al., 2021). Our ongoing studies strongly suggest that the developmental measure is a more sensitive and predictive measure of the construct underlying the measurement of weight suppression, as it relates to both psychological and biological indices of disordered eating more strongly than the traditional weight suppression measure.

Beyond our grant-funded studies, most of our other eating disorders research has been conducted in collaboration with the Renfrew Center for eating disorders. Their headquarters and one of their main treatment centers is in Philadelphia. I have been a research consultant, and a member of their Clinical Excellence Board, for many years. Renfrew is the largest treatment center for eating disorders in the country and therefore offers the unique ability to collect data on a large number of eating disordered patients in a relatively short time. The data available at Renfrew has created many opportunities for data collection for masters and dissertation research projects. Examples of research conducted at Renfrew can be found here: (Lowe et al., 2011; Thompson-Brenner et al., 2021).

Hundreds of research studies have found that medically significant weight losses can be achieved by lifestyle change programs.  However, lost weight starts to be regained once treatment ends. In the past 20 years we have received several NIH grants to study the prevention of weight gain and, after a weight loss, the prevention of weight regain. Our approach to the prevention of weight regain involves a significant departure from the traditional "lifestyle change" approach to weight control (Lowe, 2003). This departure is based on our conclusion that making significant, lasting changes in the self-regulation skills of individuals with obesity is a sub-optimal approach for achieving lasting weight change. Our alternative approach, called “Nutritrol,” instead emphasizes helping people change the composition of their diets (e.g., reducing fat, increasing water- and fiber-rich foods, increasing sources of lean protein) and making numerous changes in the foods in their home food environments. Our studies have shown significant improvements in long-term weight loss outcomes relative to the standard behavioral weight loss approach (see Lowe et al, 2014, Lowe et al., 2018).

In April of 2021, Dr. Lowe (along with Sue Roberts from Tufts and Matt Hayes from University of Pennsylvania) was awarded one of two grants as part of a NIH consortium studying the physiology of the weight reduced state. This project will measure multiple metabolic and appetitive processes during and after a group of individuals with obesity lose weight. These measurements will be used as predictors of weight regain following a weight loss achieved via a behavioral weight loss program. The grant is for 5 years.

Being able to directly measure brain responses to relevant stimuli represents a powerful method for deepening our understanding the consequences of dieting and the symptoms of disordered eating. In one set of studies, we have used EEG or fMRI to better understand differences between restrained eating and dieting (Ely et al, 2014), the underpinnings of binge eating (Ochner et al., 2009; Winter et al., 2017) and why weight suppression is so consistently related to eating disorder symptoms (based on in-progress analyses of neuroimaging data supported by a NIMH grant that ended recently). In our current grant on the physiology of the weight-reduced state, we are also using fMRI to study individuals with obesity before and after they lose weight.

To better understand the predisposition that may make some people more susceptible to food-related temptations, my research team has developed a measure of the drive to eat purely for pleasure (i.e., when not in a state of caloric deficit). It is called the Power of Food Scale (PFS), a copy of which can be found here (PFS; NOTE: permission is required to use this scale in research). 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 appetitive drive for food resulting from an interaction of personal susceptibility and the obesogenic environment. The PFS has been used by hundreds of researchers around the world, including researchers at Weight Watchers and Pfizer. The PFS measures susceptibility to loss of control eating (Espel et al., 2018), susceptibility to experiencing metabolic derangements independently of BMI (Aliasghari et al., 2019) and a mechanism (hedonic hunger) that may explain the beneficial impact of cognitive-behavior therapy on eating disorders (Felonis & Juarascio, 2020).

Humans usually maintain their body weights over periods of months or years with remarkable stability. This stability usually occurs automatically, that is, in the absence of conscious effort. Nonetheless, individuals do show small, short-term variability in their weights, with some individuals showing greater within-subject weight variability than others. We proposed several years ago that greater variability in weights over time might imply reduced precision in mechanisms governing energy balance, which might also imply a greater susceptibility to weight gain in the future. We have now studied this hypothesis and found support for it in several studies. For instance, we have shown that college students who show greater variation in their weight over a 6-month period gain more weight over the next 18 months (Lowe et al 2015). Individuals with obesity who are losing weight ultimately lose less weight if there is greater week-to-week variability in their weights while they are losing weight (Feig et al, 2017). Amani Piers, my doctoral student, recently found the same effect in those with anorexia nervosa. We have even shown this effect in newborns – that is, newborns who showed more variability in their weights during the first year of life gained more weight in the second year of life (Lowe, 2021). We hope to better understand the behavioral and biological mechanisms that mediate these effects in future research.