Is the habit system altered in individuals with obesity? A systematic review

Abstract

Habit-like eating behavior is repeatedly pointed to as a key cognitive mechanism contributing to the maintenance of overweight and obesity. Here, we conducted a systematic review of the literature to assess the existent behavioural evidence for the Habit Hypothesis for Overeating (HHO) which states that overweight and obesity are the consequence of an imbalance between the habit and goal-directed reward learning systems, leading to overconsumption of food. We found a total of 16 studies implementing a variety of different experimental protocols (i.e., free operant paradigm, slips-of-action test, two-step task, Pavlovian-to-Instrumental (PIT) paradigm, probabilistic learning task) and manipulations that rely on radically different theoretical stances. Studies using satiety-based outcome devaluation procedures as well as probabilistic learning tasks seem to provide preliminary evidence for the HHO. However, findings from different outcome devaluation procedures, sequential decision-making tasks, and PIT paradigms fail to show increased habitual eating behavior propensity in obesity. Taken together, the results of these studies do not support the HHO conclusively. More research along these lines is needed, as if proved, HHO might have a transformative impact on public health, shifting the traditional framework in the treatment and prevention of overweight and obesity.