The research meal consisted of eggs, turkey sausage, biscuits and gravy - roughly equivalent in calories and fat to a loaded two-patty hamburger and French fries at a fast-food restaurant. Participants were required to eat the entire meal within 20 minutes.
"This is not an extraordinary meal compared to what many of us would grab when we're in a hurry and out getting some food," said Kiecolt-Glaser, also director of the Institute for Behavioral Medicine at Ohio State.
The control for comparison in this randomized trial was that one meal contained saturated fat and another was high in a different kind of fat: sunflower oil containing monounsaturated fat, which is associated with a variety of health benefits.
"We suspected that the saturated fat would have a worse impact on metabolism in women, but in our findings, both high-fat meals consistently showed the same results in terms of how stressors could affect their energy expenditure," said Martha Belury, professor of human nutrition at Ohio State and a co-author of the study.
Before the meal, participants rested for 30 minutes and their energy expenditure - or calories burned by converting food to energy - was tested during that time. After they ate their meal, their metabolic rate was tested for 20 minutes of every hour for the next seven hours. Researchers obtained this data by using equipment that measured inhaled and exhaled airflow of oxygen and carbon dioxide.
"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."