A large study with almost 80,000 women concludes that being underweight increases the risk of experiencing early menopause. The study, led by researcher Kathleen Szegda of the University of Massachusetts in Amherst (USA), is published in the journal Human Reproduction.
The experts started from the approach of previous research in which the high and low levels of fat had been related to reproductive function. The hypothesis was that a woman’s weight can also affect the time when menopause begins.
To test this theory, the researchers analyzed data from 78,759 women from the Nurses’ Health Study II, and followed them clinically between 1989 and 2011. The women were between 25 and 42 years old, and information was gathered about their height, weight, and menopause status through a questionnaire. This information, together with the data on the use of hormonal therapy, was updated every 2 years.
For the study, “early menopause” was defined when it occurred before the woman turned 45.
The experts used multiple regression models to assess the early risk of menopause, and in general, 2,804 women in the study reported experiencing it.
The risk of early menopause increased by almost a third
The National Institutes of Health (NIH) consider that a weight between 18.5 and 24.9 kilograms per square meter is normal , while women weighing less than that amount are considered underweight (for example, measuring 1.70 cm and weighing 53 kg or less would place us in patients at risk of early menopause).
In the study, women with a body mass index (BMI) of less than 18.5 kilograms per square meter, at any age, were 30% more likely to experience early menopause compared to women who’s BMI was between 18.5 and 22.4 kilograms per square meter.
The researchers also found that women whose BMI was between 25 and 29.9 kilos per square meter (for example, measuring 1.70 cm and weighing 73 kg or more) were up to 30% less likely to experience early menopause. The highest probability of having early menopause seemed to be among women who, when they were 18 years old, had a body mass index below 18.5 kilos per square meter and reported experiencing a “severe weight cycle”.
Finally, women who had a BMI less than 17.5 kg per square meter at the age of 18 (for example, measuring 1.70 cm and weighing 50 kg), were 50% more likely to have early menopause compared with the women with normal weight.
“Those women who weigh less than normal in early or mid-adult age may be at increased risk of early menopause,” sums up Szegda. This is “associated with an increased risk of cardiovascular disease and other health conditions such as cognitive impairment, osteoporosis and premature death, so these findings have important implications for women and their doctors,” she explains.
Low weight = BMI less than 18.5 kg / m².
Normal weight = BMI between 18.5 and 24.9 kg / m².
Overweight = BMI between 25 and 29.9 kg / m ².
Obesity grade I = BMI between 30 and 34.9 kg / m²
Obesity grade II = BMI between 35 and 39.9 kg / m².
Obesity grade III (morbid obesity) = BMI higher than 40 kg / m ².