Hormonal changes each month, part of the menstrual cycle, can cause women to eat more—a normal, biological occurrence.

This increased food intake causes some women to become much more preoccupied with their body weight and shape, and this intensified obsession can increase the risk of developing eating disorder symptoms, new research shows.

The crux of the matter is that women are biologically wired to increase their food intake during their monthly cycle in preparation for pregnancy—it’s supposed to happen.

Study author Kelly Klump, a professor at Michigan State University, says the changes in food intake are all part of a natural, evolutionary process. Each month, women’s bodies undergo a menstrual cycle marked by changes in the hormones estrogen and progesterone.

These monthly fluctuations in hormones cause women to increase the amount of food they eat. These changes can also cause emotional eating, which is the tendency to over-consume food in response to negative emotions.

“In our culture, we tend to view any increased eating by a woman as a negative thing, even when that gain is biologically and evolutionarily driven,” Klump says.

“This is a potentially dangerous chain of events that could lead to serious and life-threatening eating disorders, including anorexia nervosa and bulimia nervosa. This can be especially problematic during the holidays.”

In a study published in the International Journal of Eating Disorders. Klump and co-lead author Britny Hildebrandt, a Michigan State graduate student, say future work in this area will try to determine what other factors, in addition to emotional eating, drive pathological eating disorder symptoms in women across reproductive and hormonal stages.

The National Institute of Mental Health supported the work. Researchers from Michigan State, Ohio University; Florida State University, Virginia Commonwealth University, and the University of Virginia contributed to the work.