Researchers believe counseling to mitigate unwanted weight gain would help women stay on birth control, prevent more unintended pregnancies

Researchers at the University of Southern California (USC) have found that the contraceptive injection depo medroxyprogesterone acetate (DMPA), more widely known as Depo-Provera, can increase activity in the “reward” areas of the brain stimulated by food. Additionally, these areas of the brain were significantly more responsive to high-calorie foods like pasta and ice cream, as opposed to low-calorie, healthy foods like salads and fresh fruit. This is the first neuroimaging study to evaluate the effect of hormonal birth control on food motivation. The study was published in Contraception and funded by The Society of Family Planning and the USC Department of Radiology.

“This was a multidisciplinary and groundbreaking approach to understanding weight gain associated with DMPA that required the expertise of researchers in obstetrics and gynecology, neuroradiology, neuroscience, biochemistry, biokinesiology and endocrinology,” said senior author Penina Segall-Gutierrez, MD, who oversaw the research as an assistant professor of clinical obstetrics and gynecology at Keck Medicine of USC.

Selected participants were healthy, non-obese, non-pregnant females ages 18 to 45 years with no history of bariatric surgery or diabetes. They also had not used DMPA within the last six months or any other form of hormonal contraception within the last three months.

Each participant had two functional magnetic resonance imaging (fMRI) sessions – one prior to receiving a DMPA injection and one eight weeks after receiving the injection. At each session, they were shown a randomized stream of images from three categories: non-edible objects, healthy foods and high-calorie foods. Participants saw five images per category, and each image was projected only once for 3.5 seconds. Neurologists took images of the brain during the viewing, as well as a whole-brain anatomy scan.

After eight weeks of taking DMPA, the images showed increased activity from the first fMRI session in the orbitofrontal cortex, insular cortex, occipital fusiform gyrus, cingulate gyrus and left amygdala when subjects looked at food versus inedible objects. Viewing high-calorie foods compared to low-calorie foods resulted in significantly more activity in the insular cortex, left and right orbitofrontal cortex, and the lateral occipital cortex.

“The images showed increased activity in the areas of the brain that motivate you to eat after eight weeks of DMPA initiation,” said Katie Page, MD, assistant professor of medicine, Division of Endocrinology and Metabolism at Keck School of Medicine and chair of Maternal-Child Health, USC Diabetes and Obesity Research Institute. “Treatment with Depo-Provera for eight weeks was associated with greater activation in brain areas involved in reward processing when participants were viewing pictures of high-calorie comfort foods”. While none of the subjects gained a significant amount of weight over the short duration of our study, other studies have shown a strong correlation with increased activity in these regions and future weight gain.

DMPA is a commonly used form of contraception, in no small part for its convenience and effectiveness. Rather than taking a daily pill, women need only receive an injection from their doctor once every three months, and DMPA is more than 99 percent effective at preventing pregnancy when all injections are administered on time. The National Survey of Family Growth reports that 22 percent of sexually active women ages 15 to 44 have received a DMPA injection. However, weight gain is a common complaint amongst users, and may influence them to stop receiving injections altogether. A study in the American Journal of Obstetrics and Gynecology found that women using DMPA gained an average of 11 pounds in three years and a three percent increase in body fat, as compared to three to four pounds gained and just over one percent increase in body fat for other forms of contraception.

“These findings can help clinicians better counsel women who choose DMPA on the possible weight gain that they may experience, and encourage women to speak with their providers about how to prevent and monitor weight gain while on this effective method of contraception instead of suddenly discontinuing the method which can lead to unintended pregnancy ,” said lead author Tania Basu Serna, MD, MPH. “The more we understand about unwanted side effects of contraception, the more we can improve the way we counsel and manage side effects so that the woman feels comfortable with the method she is on.”

by Mary Dacuma