The Dangers of a Low-Calorie Diet That Changes Your Period

Following a low-calorie diet may affect your period.
Image Credit: Pascal Kiszon/iStock/GettyImages

If you're following a strict diet and notice your menstrual cycle is off, you might be wondering: Can changing your diet change your period? Although a late or missed period can happen for several reasons, following a low-calorie eating plan may impact your period and your health.


Read more:How Does Exercising Affect Your Period?

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Low-Caloric Intake Affects Your Period

"Severe calorie restriction can cause weight loss, but it can also cause periods to disappear," says Allison Hill, MD, an obstetrician and gynecologist with Spectrum Women's Healthcare in Los Angeles.


According to the Office on Women's Health, (OWH), missed periods can happen when a low-calorie diet causes rapid weight loss or you drop too many pounds. According to ​Dietary Guidelines for Americans, 2020-2025​, published by the U.S. Department of Agriculture and U.S. Department of Health and Human Services, most females should eat between 1,600 and 2,200 calories a day. That range reflects differing levels of physical activity, body composition and other factors.


More Dangers of Low-Calorie Diets

Low caloric intake can wreak havoc on your health, which causes both short-term and long-lasting problems. "A low-calorie intake or calorie-restricted diet can suppress ovulation, which can lead to infertility and lack of menstrual bleeding, especially if the calorie restriction is severe," says Yvonne Bohn, MD, FACOG, an obstetrician and gynecologist with Santa Monica Women's Health in Santa Monica, California.


When you severely limit the number of calories you're eating, your body essentially stops the hormones required for ovulation from being produced, which in turn causes your period to stop, according to the NHS, the U.K.'s public health service.

But even if fertility is not a current concern, another serious health threat, Dr. Bohn says, is the athlete triad. "The athlete triad occurs when the following three problems persist amongst athletes or people with a high activity level: weight loss, amenorrhea (irregular or missed periods) and low bone mass (weakened bones)."


These three issues are all interconnected. "If you lose too much fat, you will lose muscle mass, resulting in decreased estrogen levels. Decreased estrogen levels can directly affect your periods, which can then lead to weak bones," Dr. Bohn says.


The second part of the triad, amenorrhea (when periods don't occur) is classified as primary or secondary. According to the National Institute of Child Health and Human Development (NICHD), primary amenorrhea occurs in people who haven't gotten their first period before the age of 16. In these cases, it can be affected by genetic factors, but also lifestyle factors such as excessive exercise, low-calorie diet or extreme psychological stress. These things can disrupt normal, healthy function.


Secondary amenorrhea, notes NICHD, is when a person misses three periods in a row or doesn't have a period for six months. It may occur as a result of other circumstances, but it may also be the result of weight changes. "Both forms of amenorrhea can result from high or low caloric intake, eating disorders, over-exercising and poor diet," Dr. Bohn says.

Other Reasons for an Irregular Period

A low caloric intake or making changes to your diet are not the only reason your period may be irregular or not showing up at all. According to the OWH, some other reasons your period might be taking a break include:


  • Polycystic ovarian syndrome (PCOS).
  • Too much exercise.
  • Hormonal changes.
  • Hypothyroidism.
  • Lactation/breastfeeding.
  • Hormonal contraception such as the Mirena IUD or birth control pills.
  • Stress.
  • Pelvic inflammatory disease.
  • Certain medications.
  • Obesity.

If you are experiencing disordered eating or are worried that you might be at risk of developing disordered eating, help is available. The first place to start is with your doctor, who can help you access community resources, including mental health experts and dietitians that specialize in eating disorders.


Beyond your doctor's office, there are several online resources available that can provide more information on disordered eating, including the National Eating Disorders Association and National Institute of Mental Health.

Read more:7 Signs Your 'Healthy Diet' Is Actually Disordered Eating




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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