May 7, 2014
Kirstin Aschbacher, PhD, of the University of California in San Francisco, and colleagues studied the effects of foods high in sugar and fat (highly palatable foods [HPF]) on metabolic risk in 33 postmenopausal women who were caregivers (cases) and 28 age-matched women with low stress (controls).
The researchers found that greater consumption of HPF was associated with increased levels of abdominal adiposity, oxidative stress, and insulin resistance at baseline (all P≤0.01) in chronically stressed women but not in women with low stress. Plasma peripheral neuropeptide Y (NPY) level was significantly greater in cases than in controls. Among women with high versus low levels of NPY, the association of HPF with abdominal adiposity was stronger. Little change occurred in the primary outcomes at one year.
"The implication of this work is that chronically stressed individuals are more vulnerable to a high-fat/high-sugar diet," the authors write. "If confirmed, these data invite the exciting possibility that increasing resilience skills could improve the efficacy of interventions to help individuals lose weight and manage metabolic syndrome, even if diet and activity levels remained the same."
In preclinical studies, the combination of chronic stress and a high sugar/fat diet is a more potent driver of visceral adiposity than diet alone, a process mediated by peripheral Neuropeptide Y (NPY).
In a human model of chronic stress, we investigated whether the synergistic combination of highly palatable foods (HPF; high sugar/fat) and stress was associated with elevated metabolic risk. Using a case-control design, we compared 33 post-menopausal caregivers (the chronic stress group) to 28 age-matched low-stress control women on reported HPF consumption (modified Block Food Frequency Questionnaire), waistline circumference, truncal fat ultrasound, and insulin sensitivity using a three-hour oral glucose tolerance test. A fasting blood draw was assayed for plasma NPY and oxidative stress markers (8-hydroxyguanosine and F2-Isoprostanes).
Among chronically stressed women only, greater HPF consumption was associated with greater abdominal adiposity, oxidative stress, and insulin resistance at baseline (all p's ≤.01). Furthermore, plasma NPY was significantly elevated in chronically stressed women (p<.01), and the association of HPF with abdominal adiposity was stronger among women with high versus low NPY. There were no significant predictions of change over one-year, likely due to high stability (little change) in the primary outcomes over this period.
Chronic stress is associated with enhanced vulnerability to diet-related metabolic risk (abdominal adiposity, insulin resistance, and oxidative stress). Stress-induced peripheral NPY may play a mechanistic role.