For the first time in humans, a small study has shown that chronically stressed women whose diet contains high-fat and high-sugar foods are more vulnerable than low-stressed women who eat the same foods to metabolic health risks, including abdominal fat and insulin resistance.
If the association is confirmed in interventional studies, the finding suggests that increasing stress-resilience skills might improve on interventions to treat metabolic syndrome and obesity, which have reached epidemic proportions.
"In order for scientists and doctors to give the public better and more reliable answers about what they can do about their stress, we need support for this kind of research — how stress and resilience training affects biology," first author Kirstin Aschbacher, PhD, assistant professor of psychiatry at the University of California, San Francisco (UCSF) told Medscape Medical News.
The study was published online April 12 in the journal Psychoneuroendocrinology.
Inspired by a 2007 research article that associated stress with development of fat gain and metabolic syndrome in mice, primarily through activation of neuropeptide Y (NPY), Dr. Aschbacher and colleagues conducted a case-control study comparing 33 postmenopausal caregivers as the high-stress group with 28 age-matched, low-stress women.
The high-stress group consisted of women caring for a spouse or parent with dementia for an average of 4.7 years.
Participant characteristics included a mean age of 62 years and a median income of $70,000 to $79,000; 66% had a bachelor's or advanced degree, and 80% were white.
The participants self-reported their dietary consumption on food frequency questionnaires, and both groups reported eating high-fat/high-sugar foods.
Researchers took fasting blood samples from participants at UCSF and measured abdominal fat through dual-energy X-ray absorptiometry.
They also measured NPY levels in plasma.
Participants underwent a 3-hour oral glucose test immediately after their fasting blood draws.
All measures were taken at baseline and 1 year later and largely remained at the same levels because of the high stability of outcomes over time.
The high-stress group reported a mean time of caregiving of 13.6 hours a day, compared with no hours of caregiving for the low-stress group.
The chronically stressed group did not report a significantly higher consumption of high-fat, high-sugar foods than the low-stress group, but providing more hours of care per day in the high- stress group was associated with more high-fat, high-sugar food consumption (P = .03) and had significantly higher levels of NPY (P = .001). Controlling for age, physical activity, and medication use, the researchers found that higher consumption of high-fat, high-sugar foods was associated with greater activation of NPY and waistline circumference (P = .02), truncal fat (P = .01), and insulin sensitivity (P = .04), but not levels of 8-hydroxyguanosine, a marker of RNA oxidation (P = .40).
"Our data are the first to demonstrate in humans that the synergistic combination of chronic stress along with consuming more high-fat/high-sugar foods was associated with significantly worse metabolic outcomes and greater waist circumference," the researchers write. "[T]his study represents a critical step needed to justify considerably more resource-intensive studies involving feeding paradigms, multiple daily dietary assessments, and biomarkers for macronutrient consumption."
An independent expert agrees. "Now is exactly when we need this kind of research. A lot of prior research has really focused on one thing at a time. I really think this kind of study is so valuable because we are not just in a bubble where you're stressed. Now I'm in a different bubble where I'm hungry. This kind of tie-in that looks at the interaction of all of these factors is so important," A. Janet Tomiyama, PhD, assistant professor of psychology at the University of California, Los Angeles, told Medscape Medical News.
"They took this really interesting finding in rodents and are actually bringing it the human arena, which I think is already a huge step forward in terms of making it relevant to everyday people. It makes us more confident that it is a mixture of stress and food that is contributing to this [reduced] metabolic health," she continued.
She added that an intervention into the types of foods eaten while stressed could be done quickly. "We don’t reach for celery when we're stressed. We reach for brownies and potatoes. We're really far from [a treatment] still. But one place that combines the 2 factors [stress and diet], is where we could — I think tomorrow — create an intervention."
"When you have diabetes, doctors know what to measure in your blood to see whether your treatments are working," Dr. Aschbacher said. "But right now there's no consensus about what biological measures we should use to judge whether or not a stress management program is really working to improve your health.
"When you look at guidelines published by some of the leading organizations, the focus for metabolic health is really on diet and exercise. I hope that in the future, stress management will become integrated as an important part of good preventative care," she added.
This research was supported by the National Institutes of Health, the Marchionne Foundation, and the Institute for Integrative Health. The authors and Dr. Tomiyama have reported no relevant financial relationships.
Psychoneuroendocrinol. Published online April 12, 2014. Abstract
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Cite this: Chronic Stress, Poor Diet May Up Metabolic Risk - Medscape - May 05, 2014.