12/24/2014 08:44 am ET Updated Dec 24, 2014

How Your Mind Tricks You Into Feeling 'Fat' During Your Period

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It can seem inevitable. You hit the dreaded PMS week each month and you're tired, you're in pain and you feel as if you're heavier than usual for no apparent reason. Is there any crueler gender-specific biological punishment?

But before you fall into another unproductive bout of self-pity about your body, know there's new research that puts that weight-related symptom in context.

While previous studies have suggested hormones may cause a woman to obsess about body size, that hypothesis misses a very important link. The new study, published in the International Journal of Eating Disorders, suggests that it's actually the guilt a woman may feel about how much she's eating as a result of those hormones that puts her at higher risk of suffering feelings of self-loathing -- whether or not she's actually gaining weight.

"In the long run, we know that it's not that women's weights are changing dramatically as a result of this food intake," Kelly L. Klump, a psychology professor at Michigan State University and co-author of the study, told The Huffington Post. "The problem is, because there's this increased food intake and emotional eating in the moment, they feel really bad about themselves."

It's important to understand that, for the most part, this type of increased eating is a biologically-driven effect of the mid-luteal phase -- the time when a fertilized egg would implant upon conception, but your appetite ramps up even if you don't conceive. Understanding this may help women identify what's going on in their bodies and prevent unnecessary dwelling or guilt as a result of emotional eating, or eating in response to negative emotions.

"I think women can very much beat themselves up about, 'Oh, why did I eat more? Now I feel like I've gained all this weight,'" said Klump.

It's already been established that ovarian hormones predict binge eating and emotional eating, but the study's researchers set out to find the source of the over-thinking and shame they noticed anecdotally. Obsessing about body shape and size can cloud women's views of their bodies and leave them vulnerable to eating disorders on a monthly basis. Hormones seemed like a reasonable root of that thought process, but the researchers weren't sure.

To find out, they distributed daily questionnaires to track the weight preoccupation, negative feelings and emotional eating of 352 women from the ages of 15 to 25 for 45 days -- enough time for the entire sample to go through one full menstrual cycle. Researchers also took saliva samples from participants each day to track the two ovarian hormones, estradiol and progesterone.

As ovarian hormones shifted and participants entered into the mid-luteal phase of their cycles, they were more likely to engage in emotional eating, which led to increased preoccupation with weight during the premenstrual and menstrual phases. In layman's terms: Ovarian hormones predicted the emotional eating, which predicted the weight preoccupation.

The highest period of risk for emotional eating is during the mid-luteal stage -- when you have high levels of progesterone and estradiol -- but the researchers found that weight preoccupation didn't occur until after that hormonal spike.

"You're consuming larger amounts of food; you're eating in a way that's not necessarily typical for you on a day-to-day basis or even meal-to-meal," Britny Hildebrandt, a graduate student at Michigan State University and co-author of the study, told The Huffington Post. "That might be boosting this preoccupation with weight."

Of course, not every woman is going to eat more or become more preoccupied with her body at these times every single month. These findings simply suggest that your body is wired to do these things, so there is an increased chance they're going to happen.

Klump added that this pattern wouldn't be possible without the cultural messages women get about their bodies and "socially acceptable" eating habits.

"To be honest, if we didn't have such a weight-focused, weight-obsessed culture, these natural changes in food intake across the menstrual cycle would not have these effects on women," Klump said.

At the end of the day, just know that if you're extra-hungry at certain times of the month, listen to your body and free yourself of any self-judgement. It's a natural biological process, not the enemy.



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