Excessive Sugar Consumption May Be a Difficult Habit to Break: A View From the Brain and Body

Abstract

Context: Sugar overconsumption and chronic stress are growing health concerns because they both may increase the risk for obesity and its related diseases. Rodent studies suggest that sugar consumption may activate a glucocorticoid-metabolic-brain-negative feedback pathway, which may turn off the stress response and thereby reinforce habitual sugar overconsumption. Objective: The objective of the study was to test our hypothesized glucocorticoid-metabolic-brain model in women consuming beverages sweetened with either aspartame of sucrose. Design: This was a parallel-arm, double-masked diet intervention study. Setting: The study was conducted at the University of California, Davis, Clinical and Translational Science Center's Clinical Research Center and the University of California, Davis, Medical Center Imaging Research Center. Participants: Nineteen women (age range 18–40 y) with a body mass index (range 20–34 kg/m2) who were a subgroup from a National Institutes of Health-funded investigation of 188 participants assigned to eight experimental groups. Intervention: The intervention consisted of sucrose- or aspartame-sweetened beverage consumption three times per day for 2 weeks. Main Outcome Measures: Salivary cortisol and regional brain responses to the Montreal Imaging Stress Task were measured. Results: Compared with aspartame, sucrose consumption was associated with significantly higher activity in the left hippocampus (P = .001). Sucrose, but not aspartame, consumption associated with reduced (P = .024) stress-induced cortisol. The sucrose group also had a lower reactivity to naltrexone, significantly (P = .041) lower nausea, and a trend (P = .080) toward lower cortisol. Conclusion: These experimental findings support a metabolic-brain-negative feedback pathway that is affected by sugar and may make some people under stress more hooked on sugar and possibly more vulnerable to obesity and its related conditions.