Typical high-carbohydrate, low-fat breakfasts, such as cereal or toast, may not be as healthy as previously thought, if results from a new mouse study are shown to apply to humans, researchers say.
Researchers at the University of Alabama at Birmingham (UAB) examined how eating meals with high fat content at different times of the day affected metabolic syndrome in mice. Metabolic syndrome is a condition characterized by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type 2 diabetes and cardiovascular disease.
The researchers found that those mice that ate a high-fat meal early in the day and a low-fat meal later were better able to process fat throughout the day than those that ate a high-carbohydrate meal upon waking. Conversely, they wrote that those that ate high-fat meals at the end of their waking period had more symptoms of metabolic syndrome, despite no difference in total caloric intake or in calories from fat.
Professor of epidemiology at UAB and lead author of the study Molly Bray said: "Humans eat a mixed diet, and our study, which we have repeated four times in animals, seems to show that if you really want to be able to efficiently respond to mixed meals across a day then a meal in higher fat content in the morning is a good thing. Another important component of our study is that, at the end of the day, the mice ate a low-caloric density meal, and we think that combination is key to the health benefits we've seen."
Bray said that high-fat meals upon waking seemed to ‘turn on’ fat metabolism and improve the body’s ability to metabolize different types of food later in the day.
Study senior author and associate professor of medicine at the UAB Division of Cardiovascular Disease Martin Young said: “Consumption of a typical breakfast of cereal or toast may not necessarily be the best time of day at which a carbohydrate-rich meal should be consumed; instead, perhaps bacon and eggs.”
Bray and Young cite several time-specific eating behaviors that they say are known to have impacts on weight: Skipping breakfast has been linked to higher BMI (body mass index), for example; night eating has been associated with higher BMI; and it has been suggested that carbohydrate-rich breakfasts reduce caloric intake later in the day.
“Despite a clear time of day dependence for these reported observations, total caloric intake is typically considered the primary cause of elevated BMI in human beings,” the authors wrote.
They concluded: “The findings of this study suggest that dietary recommendations for weight reduction and/or maintenance should include information about the timing of dietary intake, as well as the quality and quantity of intake.”
Source: International Journal of Obesity
Published online ahead of print March 30, 2010
"Time-of-day-dependent dietary fat consumption influences multiple cardiometabolic syndrome parameters in mice"
Authors: MS Bray, J-Y Tsai, C Villegas-Montoya, BB Boland, Z Blasier, O Egbejimi, M Kueht and ME Young