Background: Excessive consumption of high-fat, high-sugar foods is implicated in the pathogenesis of obesity, binge-eating disorder and ‘food addiction’, estimated to affect one in five young Australians. Food addiction comprises a range of harmful eating behaviours derived from aspects of substance use disorder, including escalation of intake over time, high motivation for food reward, and compulsive consumption that continues despite adverse consequences. However, the relative prevalence of food addiction behaviours in obesity versus binge eating remains unclear. This study tested measures of escalation, motivation and compulsion for a high-fat high-sugar food in animal models of diet-induced obesity and binge-eating.
Method: Over a seven-week diet intervention, three groups of young adult female Sprague-Dawley rats (n = 12) were fed chow and water only (Control) or chow and water supplemented with continuous or restricted (1h/day, 3x/wk) access to sweetened condensed milk (SCM). Addiction-like behaviour was quantified by assessing (1) escalation of SCM intake over time; (2) motivation for SCM in progressive ratio tests; and (3) compulsive intake of SCM when adulterated with quinine and during a modified novelty-suppressed feeding test.
Results: Across the diet intervention, percent weight gain was greater in the Continuous group than the Control group, with intermediate weight gain in the Restricted group. Only the Restricted group exhibited ‘binge-like’ escalation of SCM intake and compulsive consumption of SCM in both the quinine adulteration test and the novelty suppressed feeding test, relative to Continuous and Control groups. However, motivation for SCM did not differ between groups, as assessed by progressive ratio breakpoints.
Conclusions: A preclinical model of binge eating (Restricted group) more closely recapitulated the phenotype of food addiction than diet-induced obesity (Continuous group). Despite the absence of changes in motivation for SCM, the pattern of access to high-fat, high-sugar foods appears the key predictor of addiction-like behaviour.