"By measuring the gas exchange, we can determine their metabolic rate: how much energy their body needs during the time being measured," Belury said. "The participants burned fewer calories over the seven hours after the meal when they had a stressor in their life the day before the meal."
Researchers also took multiple blood samples "so we could follow throughout the day what was happening metabolically after eating the high-fat meal," Kiecolt-Glaser said.
The stressors' effects of increasing insulin had a time element: Insulin spiked soon after the high-fat meal was consumed and then decreased to roughly match insulin levels in nonstressed women after another 90 minutes.
A history of depression alone did not affect metabolic rate, but depression combined with previous stressors led to a steeper immediate rise in triglycerides after the meal. Triglycerides are a form of fat in the blood, and high levels are considered a risk for cardiovascular disease.
"With depression, we found there was an additional layer. In women who had stress the day before and a history of depression, triglycerides after the meal peaked the highest," Kiecolt-Glaser said. "The double whammy of past depression as well as daily stressors was a really bad combination."
The researchers are reluctant to extend these findings to men because men tend to have more muscle than women, which would affect their metabolic rate, Belury said.
But the findings do offer one more motivation to keep healthful foods nearby.
"We know we can't always avoid stressors in our life, but one thing we can do to prepare for that is to have healthy food choices in our refrigerator
|Contact: Jan Kiecolt-Glaser|
Ohio State University