Obesity is excess fat in the body of a person with a BMI of 30 kg/m2 or more. It is the excess fat around the abdomen (central obesity) that is dangerous and not the subcutaneous fat around the hips and the thighs. That is why the abdominal circumference is also important when weighing the health risks of an obese person.

Besides these health risks such as heart disease, hypertension, diabetes, and sleep apnea in men, obese women of reproductive age expose themselves to an additional complication of menstrual irregularities. These irregularities may pertain to the menstrual bleeding and/or the menstrual cycle.

Besides menstrual cycle disturbances, being obese can significantly reduce your chances of conception and pregnancy.

Women with severe central obesity are three times more prone to have menstruation irregularities as compared to women with a healthy weight.

The risk of menstrual disorders is double in women with a BMI of 24–25 (overweight women) and fivefold higher in those with a BMI of 35 or more (morbidly obese women).

The menstrual irregularities can be in the form of variation in the length of the menstrual cycle, the regularity of the periods and the amount of bleeding.

Even a 20% increase in body weight can cause amenorrhea (absence of period). Incidentally, even weight loss has been shown to influence menstrual cycle regularity.

Normal menstrual cycle

The length of the menstrual cycle varies among women but in most, the normal cycle lasts anywhere between 26 to 34 days.

Short cycle

Short cycles are those that last for less than 25 days, while long cycles are those that last for 35 days or more.

Irregular cycle

Irregular cycles are those when there is more than 15 days’ difference between longest and the shortest cycle during the past year.

What types of menstrual problems can occur in obese women?

Obese women can have the following menstrual problems.

  • Amenorrhea (absence of periods)
  • Oligomenorrhoea (light or infrequent menstrual periods)
  • Dysmenorrhea (heavy and painful periods)
  • Prolonged bleeding that can last for weeks
  • Unpredictable irregular periods (early or late periods)
  • Why obesity disturbs the menstrual cycle and menstruation?

The main cause of menstrual disturbances in obese women is hormones. Your hormones control your menstrual cycle. Estrogen is one such important hormone.

What does estrogen do?

Besides other functions, estrogen is responsible for the development of the inner uterine lining during each menstrual cycle. This is done to facilitate the implantation of the fertilized ovum.

However, if the ovum is not fertilized during that particular cycle, the thickened uterine lining (called the endometrium) is shed off during the menstrual period.

When you are overweight or obese, you build up fat cells that produce estrone, which is a form of the estrogen hormone.

More fat cells mean more amount of estrogen, which translates into a more thickened endometrium.

You, therefore, will then bleed more during menstruation and this can go on for a prolonged period.

Excess amounts of fat cells produce an excess amount of estrone. This can interrupt the regular secretion of other menstrual hormones, causing infrequent periods.

The excess estrogen can affect how often you have periods, and can also cause your periods to stop.

To summarize

Fat cells produce estrogen and therefore obese women have higher estrogen levels as happens during pregnancy. High estrogen levels produce the effect of a pregnancy though pregnancy does not exist. Ovaries, therefore, stop ovulating and menstruation stops. That is why obese women have amenorrhea or no periods.

Other causes for menstrual disturbances in  obesity

Insulin resistance most commonly seen in obesity causes the polycystic ovarian syndrome in which again periods remain absent.
Poor nutrition in obesity is also seen due to the fact that the obese women eat high-calorie foods that may not be nutritious. Poor nutrition is a cause for anemia, which is responsible for scanty or no periods.

How to set it right?

Losing even five percent of your body fat can regularize your menstrual cycle and facilitate pregnancy.

The reason for this is that fewer fat cells mean fewer amounts of excess hormones, which is the reason for menstrual irregularities.

What should you do?