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A new study looks at how parents’ weight status may be linked to their child’s weight. MStudioImages/Getty Images
  • Parents’ weight status in middle age can influence their child’s weight at the same age.
  • A person is six times more likely to be living with obesity in middle age if both their parents had obesity at the same age.
  • Genes play a role, but other factors are also involved, such as a family’s dietary and physical activity habits and racism and discrimination.

Your risk of living with obesity in middle age is influenced by whether your parents had obesity at the same age, a new study suggests.

In a multigenerational study in Norway, researchers found that people were six times more likely to be living with obesity in middle age if both their parents had obesity at that age.

If only one parent had obesity in middle age, the risk of obesity was more than three times higher.

“Previous research shows a strong association between parents’ and their children’s obesity status but few studies have investigated whether this intergenerational transmission of obesity continues past adolescence and into adulthood,” says study author Mari Mikkelsen, of the Department of Community Medicine, UiT Arctic University of Norway, Tromsø, Norway, in a release.

“We were interested in how parents’ BMI is related to their offspring’s BMI when the offspring is well into adulthood and has lived away from home for a long time,” she said.

The study will be presented in May at the European Congress on Obesity in Venice, Austria. It has not yet been published in a peer-reviewed journal, so the results should be viewed with caution.

Researchers used data from the Tromsø Study, a population-based health study that has been going on since 1974.

They examined data on 2,068 parent-child trios. People were middle-aged (40 to 59 years old) when they participated in the Tromsø Study — parents in 1994 to 1995 and children in 2015 to 2016.

By analyzing height and weight data, researchers found a strong association between parents’ BMI and obesity status in middle age and their child’s BMI and obesity status at the same age.

When both parents had been living with obesity in middle age, their child’s risk of having obesity at the same age was six times higher.

The risk was also greater if only one parent had been living with obesity in middle age. When only the mother had obesity, the child’s risk of living with obesity at the same age increased by 3.44 times. If only the father had obesity, the odds were 3.74 times higher.

All of these scenarios were in comparison to children whose parents did not have obesity or were not overweight in middle age.

In the analysis, researchers adjusted for the child’s sex, and for the parents’ and child’s age, education level and physical activity level.

Mikkelsen said their analysis can’t show whether the link between parents’ and child’s obesity status in middle age is due to genes or environment, “but we are most likely looking at a combination of the two.”

“From previous studies, we know that several factors contribute to the shared obesity status between parents and their children,” she said. “Genes play an important role by affecting our susceptibility to weight gain and influence how we respond to obesogenic environments in which it can be easy to eat unhealthily.”

An obesogenic environment is one that makes it easier for people to gain weight and harder for them to achieve weight loss. It includes the buildings, roads, parks, recreational areas, shops, and other businesses in a community — all of which can affect the kinds of food people eat and how easy it is for them to be physically active.

Other research has also found that a person’s risk of having obesity in childhood is greatly influenced by their parents’ weight status.

“Some studies … speculate that children tend to develop similar dietary and exercise habits to their parents when they all live together under the same roof, resulting in a similar BMI status,” said Mikkelsen.

Also, “obesity in childhood, and especially in adolescence, tends to follow the individual into early adulthood and so we suspected it would also follow them into middle age,” she said, which is what she and her colleagues found in their study.

Other studies have had similar results, showing that children living with obesity were more likely to have obesity in adolescence or adulthood, and even into middle age.

However, one study found that 70% of adults living with obesity did not have obesity in childhood or adolescence.

Because of the complex nature of obesity, a broad public health approach will be needed, with a focus on prevention among children, adolescents, and adults.

“Given the [findings] from this study, the focus should be on decreasing the likelihood of children with obesity having the disease as adults,” said Dr. Veronica Johnson, assistant professor of general internal medicine at Northwestern University Feinberg School of Medicine and a Northwestern Medicine physician, who was not involved in the new research.

“However, this doesn’t address the current disparity where Black and Latino children are [disproportionately] affected by this disease,” she said.

In 2020, the rates of obesity in the United States were 26.2% among Hispanic children, 24.8% among Black children and 16.6% among white children, according to data from the Centers for Disease Control and Prevention.

In addition, research shows that racism and discrimination, and stress resulting from those — which can affect entire communities for generations — increases the risk of developing obesity.

So “there is a need for [ongoing] efforts to not only address the overall prevalence of obesity, but also focus on the populations that need help the most,” said Johnson.

In addition, she recommends that parents learn about treatment options available to manage their own weight and their child’s.

This is especially important given that obesity increases the risk of many other health problems, including type 2 diabetes, cardiovascular disease and certain types of cancer.

However, there still remains resistance to using treatment options in children such as medications and bariatric surgery, she said, in spite of recent recommendations from the American Academy of Pediatrics.

“In this case, lifestyle interventions are imperative to manage weight,” she said. “Parents need to counsel [children] around healthful nutrition, increased physical activity and decreased screen time.”

Researchers from Norway examined data on 2,068 parent-child trios. When they analyzed height and weight data, they found a strong link between parent’s BMI and obesity status in middle age and that of their child’s at the same age.

People whose parents both had obesity in middle age were themselves six times more likely to be living with obesity at the same age. If only one parent had obesity in middle age, the risk was over three times higher.

Many factors contribute to obesity, including genetics, the environment, family eating and exercise habits, and racism and discrimination. These will need to be targeted differently to reduce the impact of parents’ weight status on that of their grown children.