Originally Published: 06 FEB 23 11:23 ET

By Katherine Dillinger, CNN

(CNN) -- People who have a healthy lifestyle before Covid-19 infection may have a lower risk of long Covid than their peers, a new study says.

The study, published Monday in JAMA Internal Medicine, looked at almost 2,000 women who reported a positive Covid-19 test between April 2020 and November 2021. The participants were enrolled in the Nurses' Health Study II, which has been surveying more than 100,000 US nurses since 1989.

The researchers looked at six modifiable lifestyle factors that they defined as healthy: a body-mass index between 18.5 and 24.7, never smoking, moderate alcohol consumption, a high-quality diet, seven to nine hours of sleep per night and at least 150 minutes per week of moderate to vigorous physical activity.

They found that a healthy pre-infection lifestyle was associated with a lower risk of Covid-19 symptoms that lasted four weeks or longer. Women who met five or six of the criteria for a healthy lifestyle had almost half the risk of long Covid as women who met none of the criteria.

"These associations were mainly driven by healthy body weight and adequate sleep," the researchers wrote in the study.

The women who had a healthier lifestyle and got long Covid had about 30% lower risk of symptoms that interfered with daily life.

The researchers speculated that the findings might be partly explained by the link between these lifestyle factors and chronic inflammation, immunity or blood clotting problems.

However, they also noted that the study's generalizability is limited because it looked only at middle-aged female nurses who were predominantly White. Other limitations include the use of self-reported data and a lack of understanding about the risk of long Covid with different strains of the coronavirus.

Previous research has linked lifestyle factors with the risk of severe Covid-19 infection, hospitalization or death, they noted, as well as overall disease and mortality.

"In the past decades, scientists have accumulated evidence that healthy lifestyle is good for overall health. However, in the U.S. for example, 70% of the population do not have a healthy body weight and 30% do not sleep enough. Findings from this study suggest that simple lifestyle changes, such as having adequate sleep, may be beneficial for the prevention of long COVID," lead study author Siwen Wang, a research fellow in the Department of Nutrition at the Harvard T.H. Chan School of Public Health, said in a statement.