Dietary Restraint Fallacy

ABSTRACT

For decades, the prevailing assumption in the field of eating disorders has been that dietary restraint causes weight gain and eating disorder symptoms, like binge eating. This belief resulted in widespread recommendations to reduce dietary restraint in treatments of eating disorders and obesity. However, recent findings by Grilo and Pittman (2024; International Journal of Eating Disorders) contradict this view, showing reduced binge frequency and greater weight loss with increased rigid dietary restraint. This commentary critically evaluates the evidence supporting a causal link between dietary restraint and overeating, highlighting the limitations of longitudinal and observational studies and the misinterpretations of early laboratory research. Importantly, randomized controlled trials and experiments that directly manipulate calorie intake show that calorie restriction improves eating control and reduces eating disorder symptoms. Conceptual issues are discussed; self‐reported dietary restraint is not an accurate reflection of actual calorie restriction. It is argued that cognitive processes like learned food cue reactivity, weak executive skills and increased reward sensitivity can explain tendencies to overeat. They are usually followed by attempts to restrain food intake—essentially reverse causality. It is further hypothesized that the eating of healthy whole foods while avoiding unhealthy ultra‐processed foods, could benefit both the prevention and treatment of all eating and weight disorders.

1. Introduction

For over half a century, the ontological assumption has prevailed that dietary restraint plays a causal role in the development of eating and weight disorders, such as binge eating and obesity. Cognitive‐behavioral models of eating disorders specifically propose a direct causal link between dietary restraint and binge eating. This perspective is widely accepted among professionals, and popular media often echo it, suggesting that dietary restraint leads to weight gain and symptoms of eating disorders. Consequently, many experts advocate for a reduction of dietary restraint in treating eating disorders and even in addressing obesity.

However, recent research by Grilo and Pittman (2024) suggests the opposite: increased weight loss and lower binge eating frequency associated with heightened rigid dietary restraint. Their findings seem to challenge the persistent and widely held belief that dietary restraint causes weight gain and binge eating and raise the question of what empirical evidence supports this fundamentally ontological model that posits dietary restraint as a causal factor in weight gain and binge eating. Is there sufficient evidence to establish a cause‐and‐effect relationship?

2. Causality

To capture the chronology and dynamics of dietary restraint and eating patterns, longitudinal studies use frequent ecological momentary assessments (EMA) or other forms of measures repeated over time. However, longitudinal observational data, including EMA over time, are limited in drawing causal inferences. Indeed, causality requires dietary restraint to precede binge eating but a temporal precedence observed in time‐series data cannot be causally interpreted without further evidence. When causation is inferred simply from the chronological sequence of two events, there is a risk of the post hoc fallacy, where multiple alternative explanations may exist for the observed order.

Experimental research is the only way to establish causality. To prove a causal link between dietary restraint and overeating, numerous laboratory studies have been conducted. Early “preload experiments” show that dietary restraint is a critical factor in counterregulation; that is, individuals high in eating restraint eat more, not less, after consuming a high‐calorie preload, which was viewed as an experimental analog of binge eating. These experiments were considered valid models of binge eating because they fit the clinical picture quite well: patients often report that consuming a small amount of “forbidden” food (i.e., breaking dietary restraint, represented experimentally by forced consumption of a high‐calorie preload) typically results in a binge. Experiments showed that restrained eaters overeat after their dietary restraint was disrupted by a high‐calorie preload or another disinhibiting stimulus, such as induced emotions or exposure to tempting food cues. These data were regarded as robust evidence supporting the theory that dietary restraint causes binge eating and it also led cognitive‐behavioral models to state that dieting induces binge eating (for an overview, see Jansen 2016). However, there is a fundamental flaw in this reasoning. Laboratory studies are indeed needed and informative for cause‐effect relationships, but because the critical factor—dietary restraint—was never manipulated in these early experiments, it cannot be concluded that dietary restraint is the cause of overeating or counterregulation. Instead, other variables, such as preload size or mood induction, were manipulated. Dietary restraint itself was not. Therefore, the only conclusion possible from these experiments is that individuals who report high dietary restraint respond differently to manipulated variables compared to those low in dietary restraint; restraint is a moderator instead of a cause of overeating. To establish dietary restraint as the cause, studies must directly manipulate dietary restraint and show that the manipulated dietary restraint induces overeating.

3. Dietary Restraint and Calorie Restriction

Contrary to what restraint theory would predict, experimental studies manipulating reduced calorie intake typically demonstrate no increase in appetite, hunger, overeating, binge eating, or other symptoms of eating disorders during calorie restriction. Instead, they show increased eating control and reduced eating disorder symptoms in addition to healthier metabolic profiles. Similarly, randomized clinical trials show that interventions inducing calorie restriction, like behavioral weight loss interventions, result in weight loss and reduced eating disorder symptoms (see for overviews: Jansen 2016; Bartholomay et al. 2024). The findings of these experimental studies and clinical trials that manipulate calorie restriction cast serious doubt on the validity of a pathway linking dietary restraint with binge eating. Grilo and Pittman (2024) are, therefore, not alone in their findings.

It should be noted that it is increasingly recognized that dietary restraint is not the same as dietary restriction (see e.g., Bartholomay et al. 2024). Dietary restraint is considered a mental effort or a cognitive intention to restrict dietary intake for the purpose of weight loss. Dietary restriction is the actual behavior of reducing calorie intake. Thus, self‐reported cognitive intentions to restrict intake define a restrained eater and not actual calorie restriction (see e.g., Bartholomay et al. 2024). But neither was it found that self‐reported calorie restriction predicts binge eating in people with binge‐eating disorder (Bartholomay et al. 2024). So, as argued earlier, there is no evidence that dietary restraint causes binge eating, nor is there evidence that calorie restriction causes binge eating.

4. Alternative Explanations

If dietary restraint is not the cause of overeating and binge eating, what is? Cognitive processes like weaker executive functions, stronger food cue reactivity, and increased reward sensitivity contribute to the tendency to overeat (Jansen, Houben, and Roefs 2015). For instance, it was demonstrated repeatedly that people with obesity have a strong drive to get rewards directly; they show an inability to delay gratification and have less effective inhibitory skills to control in particular the hedonic appetitive system, which makes it difficult to not eat when tempted. Reduced inhibition skills are associated with less weight loss in weight loss interventions and the experimental manipulation of such a cognitive response style indeed demonstrated causality between weak inhibition and overeating (see Jansen, Houben, and Roefs 2015). Further, basic appetitive conditioning processes may play a pivotal role in the maintenance of binge‐eating disorders and obesity; cued eating desires are easily learned. People quickly learn to associate cues or contexts with the intake of preferred foods; after about four to six experimental trials in which it is learned that specific cues or contexts predict the intake of preferred foods, people show conditioned eating desires in response to these cues or contexts. Increased responsiveness to cues and contexts that signal the availability of desired foods likely disrupts (intentions to) calorie restriction (van den Akker, Schyns, and Jansen 2018). Strong appetitive responding sabotages diets and promotes loss of control eating and weight gain. Then inhibitory extinction learning during food cue exposure, to reduce excessive food cue reactivity, is an appropriate and effective intervention to reduce one's reactivity to the eating cues and contexts (van den Akker, Schyns, and Jansen 2018).

5. Treatment

The current obesity epidemic exacts a heavy toll in terms of psychological and physical suffering and high healthcare costs. Reducing obesity's health burden is a major global challenge. Since achieving and maintaining substantial weight loss requires considerable effort and often proves unsuccessful in practice, preventing obesity and binge‐eating disorders is even more important. Both treatments and strategies aiming at the prevention of obesity and binge‐eating disorders should promote healthy calorie restriction, but many experts fear that this may encourage the development of eating disorders. These fears of causing eating disorders and further weight gain are however rooted in a theory with limited empirical support: the restraint theory that can now reasonably be considered falsified. Also dietary restriction does not lead to weight gain and reduces symptoms of overeating and binge eating. Calorie restriction experiments and clinical trials show that consuming fewer calories daily is demonstrably healthy in many ways.

A dietary restraint mindset usually is treated as part of successful cognitive behavior therapy. Although cognitive behavior therapy is the gold standard to treat eating disorders, it has never been dismantled to the point where it is clear how crucial the treatment of specifically dietary restraint is to its success. Reducing dietary restraint could be a goal for effective treatment of eating disorders, not because dietary restraint provokes binge eating, but because it likely reflects dysfunctional beliefs about body weight and shape as well as dysfunctional eating concerns. For these reasons, it could be good to target dietary restraint. The diet management module of cognitive behavior therapy could possibly benefit from a stronger focus on promoting healthy whole‐food diets without the downright unhealthy ultra‐processed foods characterized by large amounts of bad fats, sugars and salt and little or no fiber. Of course, patients with non‐overweight eating disorders should not restrict their calorie intake, but they too can opt for minimally processed foods for health reasons, there is nothing wrong with that, quite the contrary. The challenge will remain the same as in current eating disorder treatments: reduce calorie obsessions, embrace imperfections, avoid rigid rules, and so on. I imagine increased focus on healthy, whole‐food diets makes eating enough calories less frightening and the patient healthier, both physically and psychologically, but only experimental studies can tell.

Author Contributions

Anita Jansen: conceptualization, writing – original draft, writing –review and editing.

Conflicts of Interest

The author declares no conflicts of interest.

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.