Boston, MA--Most weight-loss plans center around a balance between caloric intake and energy expenditure. However, new research has shed light on a new factor that is necessary to shed pounds: timing. Researchers from Brigham and Women's Hospital (BWH), in collaboration with the University of Murcia and Tufts University, have found that it's not simply what you eat, but also when you eat, that may help with weight-loss regulation.
The study will be published on January 29, 2013 in the International Journal of Obesity.
"This is the first large-scale prospective study to demonstrate that the timing of meals predicts weight-loss effectiveness," said Frank Scheer, PhD, MSc, director of the Medical Chronobiology Program and associate neuroscientist at BWH, assistant professor of medicine at Harvard Medical School, and senior author on this study. "Our results indicate that late eaters displayed a slower weight-loss rate and lost significantly less weight than early eaters, suggesting that the timing of large meals could be an important factor in a weight loss program."
To evaluate the role of food timing in weight-loss effectiveness, the researchers studied 420 overweight study participants who followed a 20-week weight-loss treatment program in Spain. The participants were divided into two groups: early-eaters and late-eaters, according to the self-selected timing of the main meal, which in this Mediterranean population was lunch. During this meal, 40 percent of the total daily calories are consumed. Early-eaters ate lunch anytime before 3 p.m. and late-eaters, after 3 p.m. They found that late-eaters lost significantly less weight than early-eaters, and displayed a much slower rate of weight-loss. Late-eaters also had a lower estimated insulin sensitivity, a risk factor for diabetes.
Researchers found that timing of the other (smaller) meals did not play a role in the success of weight loss. However, the late eaters--who lost less weight--also consumed fewer calories during breakfast and were more likely to skip breakfast altogether. Late-eaters also had a lower estimated insulin sensitivity, a risk factor for diabetes.
The researchers also examined other traditional factors that play a role in weight loss such as total calorie intake and expenditure, appetite hormones leptin and ghrelin, and sleep duration. Among these factors, researchers found no differences between both groups, suggesting that the timing of the meal was an important and independent factor in weight loss success.
"This study emphasizes that the timing of food intake itself may play a significant role in weight regulation" explains Marta Garaulet, PhD, professor of Physiology at the University of Murcia Spain, and lead author of the study. "Novel therapeutic strategies should incorporate not only the caloric intake and macronutrient distribution, as it is classically done, but also the timing of food."
This research was supported by grants from Tomás Pascual and Pilar Gómez-Cuétara Foundations, Spanish Government of Science and Innovation (BFU2011-24720), Séneca Foundation from the Government of Murcia (15123/PI/10). National Heart, Lung, and Blood Institute grants HL-54776, National Institute of Diabetes and Digestive and Kidney Diseases, Grant Number DK075030 and by contracts 53-K06-5-10 and 58-1950-9-001 from the US Department of Agriculture Research, and by National Heart, Lung, and Blood Institute grant R01 HL094806, and by National Institute of Diabetes and Digestive and Kidney Diseases, grant R21 DK089378.
Brigham and Women's Hospital (BWH) is a 793-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare. BWH has more than 3.5 million annual patient visits, is the largest birthing center in New England and employs nearly 15,000 people. The Brigham's medical preeminence dates back to 1832, and today that rich history in clinical care is coupled with its national leadership in patient care, quality improvement and patient safety initiatives, and its dedication to research, innovation, community engagement and educating and training the next generation of health care professionals. Through investigation and discovery conducted at its Biomedical Research Institute (BRI), BWH is an international leader in basic, clinical and translational research on human diseases, involving nearly 1,000 physician-investigators and renowned biomedical scientists and faculty supported by nearly $625 million in funding. BWH continually pushes the boundaries of medicine, including building on its legacy in organ transplantation by performing the first face transplants in the U.S. in 2011. BWH is also home to major landmark epidemiologic population studies, including the Nurses' and Physicians' Health Studies, OurGenes and the Women's Health Initiative. For more information and resources, please visit BWH's online newsroom.