Jan 29, 2015Can Diet Stress Cause Fractures?
Cutting out the stress over eating might help reduce stress fractures in women runners. Or so a group of sports-nutrition researchers hypothesize after studying the eating attitudes and behaviors of 79 Canadian women with and without stress fractures in their legs.
Researchers at the University of British Columbia asked the runners, whose average age was 29 and most of whom were recreational distance runners, to record what they ate for three days and answer a questionnaire assessing physical activity, age, height, weight, their menstrual cycle history, and their perceived stress. Their diets were analyzed and found to be basically sound and similar, with calcium intakes about average and even slightly higher than that of American or Canadian women as a whole, according to Susan Barr, PhD, RDN, FACSM, FDC, Professor of Nutrition, who worked with lead researcher Nanci Guest, MS, CSCS, then a graduate student at UBC.
The only difference between those with stress fractures and those without was their focus on limiting what they ate, called cognitive dietary restraint (CDR). “Restraint reflects the perception that one is constantly monitoring and attempting to limit food intake,” Barr says, “but actual intakes were similar between groups.”
To explain the results, Guest and Barr note that high levels of CDR have been associated with irregularities in the menstrual cycle and increased levels of cortisol. Elevated in the “fight or flight” stress response, cortisol is a hormone that can retard muscle and bone growth and recovery from exercise. “We hypothesize that if women could avoid stressing about what they eat (and what they weigh), it might help reduce the cortisol levels that seem to be implicated in the risk for bone,” Barr says.
**Note: The study is “Cognitive Dietary Restraint Is Associated with Stress Fractures in Women Runners,” in the International Journal of Sport Nutrition and Exercise Metabolism, 15.2, April 2005, published by Human Kinetics Publishers, Inc.