Key points:
- Using data from a long-running population-based study, researchers have shown people are much more likely to be living with obesity if their parents were at a similar age.
- The odds of obesity are also raised when only one parent lives with obesity.
- It can’t be established from the analyses whether this is due to genes or environment, but the team says it is likely a combination of the two.
Individuals have six times the odds of living with obesity in middle age if both their parents lived with obesity at that age, according to new data from researchers in Norway.
“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,” said lead researcher Mari Mikkelsen from UiT Arctic University of Norway. “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.”
For the study, Mikkelsen and team used data from the Tromsø Study, an ongoing population-based health study. All individuals who were aged 40-59 years when they participated in the seventh wave of the Tromsø Study (carried out 2015-2016) and whose parents took part in the fourth wave of the Tromsø Study (1994-1995) when aged 40-59 years were included in the analysis—giving 2,068 parent-offspring trios.
According to the results, presented at the European Congress on Obesity, analysis of height and weight data showed a strong association between parents’ BMI in middle age (40-59 years) and that of their offspring at the same age. Offspring BMI increased by 0.8 units for every 4-unit increase (one standard deviation) in the mother’s BMI and by 0.74 units for every 3.1 unit increase in the father’s BMI.
There were also strong links between parents’ obesity status in middle age and that of their offspring at the same age. When both parents lived with obesity in middle age, their offspring had six times higher odds of living with obesity themselves in middle age, than adults with both parents in the normal weight range.
The odds were also raised when only one parent lived with obesity. When only the mother lived with obesity, the offspring had 3.44 times higher odds of living with obesity themselves. The corresponding number for fathers was 3.74.
“It can’t be established from our analyses whether this is due to genes or environment but we are most likely looking at a combination of the two. Whatever the explanation, our finding that obesity that is transmitted between generations can persist well into adulthood underlines the importance of treating and preventing obesity, a condition that contributes significantly to ill health and premature death,” said Mikkelsen.