Children and adolescents whose mothers follow five healthy habits -- eating a healthy diet, exercising regularly, keeping a healthy body weight, drinking alcohol in moderation, and not smoking -- are 75% less likely to become obese when compared with children of mothers who did not follow any such habits, according to a new study led by Harvard T.H. Chan School of Public Health. When both mother and child adhered to these habits, the risk of obesity was 82% lower compared with mother and children who did not.

The study will be published online in BMJ on July 4, 2018.

"Our study was the first to demonstrate that an overall healthy lifestyle really outweighs any individual healthy lifestyle factors followed by mothers when it comes to lowering the risk of obesity in their children," said Qi Sun, associate professor in the Department of Nutrition and senior author of the study.

One in five children in the U.S aged 6-19 have obesity, putting them at risk of diabetes, heart disease, and other metabolic conditions later in life. While it is known that genetics play a role in obesity, the rapid increase of the disease in recent years is likely due to changes in lifestyle and diet, indicating that "nurture" more than "nature" is fueling the current obesity epidemic.

For this study, researchers focused on the association between a mother's lifestyle and the risk of obesity among their children and adolescents between 9 and 18 years of age. They examined data from 24,289 children enrolled in the Growing Up Today Study who were born to 16,945 women enrolled in the Nurses' Health Study II.

The researchers found that 1,282 of the children, or 5.3%, developed obesity during a median five-year follow-up period. Maternal obesity, smoking, and physical inactivity were strongly associated with obesity among children and adolescents.

While the greatest drop in obesity risk was seen when mothers and children followed healthy lifestyle habits, many of the healthy habits had a noticeable impact on the risk of childhood obesity when assessed individually. Children of women who maintained a healthy body weight (body mass index 18.5-24.9) had a 56% lower risk of obesity compared with children of women who did not maintain a healthy weight, while children of mothers who did not smoke had a 31% lower risk of obesity compared with children of mothers who smoked.

The risk of obesity was also lower among children of mothers who consumed low or moderate levels of alcohol compared with children of mothers who abstained from alcohol. Because so few mothers in the Nurses' Health Study II were considered heavy drinkers, the researchers could not determine the association between heavy use of alcohol had the risk of obesity in children.

To the surprise of the researchers, mothers' dietary patterns were not associated with obesity in their children, possibly because children's diets are influenced by many factors, including school lunches and available food options in their neighborhoods.

The findings of this study highlight the crucial role a mother's lifestyle choices can have on their children's health and bolster support for family- or parent-based intervention strategies for reducing childhood obesity risk.