Children of obese parents are up to five times more likely to be overweight or obese by the time they reach their forties, new research has found
The study, by the Institute of Child Health (ICH) at University College London, is thought to be the first in the world to track the link between parents’ weight and that of their children into mid-adulthood.
Researchers looked at information from just over 4,000 people participating in the 1970 British Cohort Study to analyse weight patterns over a 32-year span – from age 10 to age 42.
Girls and boys were found to be equally likely to become overweight or obese as children, but two-thirds of men (63%) became overweight or obese in early adulthood (age 26-34), compared to only one-third of women (31%). Only 15 per cent of men were never overweight or obese between 10 and 42 years of age, compared to 40 per cent of women.
Women were therefore much more likely than men to maintain a healthy weight in early adult life, possibly due to uneven societal pressures, although this cannot be assessed from this study.
The study found that the higher the parents’ Body Mass Index (BMI) was, the more children were at risk of being overweight or obese by the time they were 42.
Children with one parent classed as obese – a BMI of 30 or higher – were just over three times more likely to be persistently overweight or obese between age 10 and 42 than those with parents who had a healthy BMI of 22.
Those with two obese parents were up to five times more likely to be persistently overweight or obese from age 10 onwards.
The vast proportion of those who became overweight or obese at any age remained so in their mid-forties.
The study also found that girls were slightly more influenced by their mother’s BMI than boys were. The daughters of obese mothers with a BMI of 30 were at more than triple the risk of being overweight or obese from childhood onwards, compared with girls who had a mother with a BMI of 22.
For boys with obese mothers this risk was doubled. Having a father with a BMI of 30 also doubled the risk of being overweight or obese from childhood onwards for both boys and girls.
The new ICH study highlights the need to prevent obesity early in life, as obesity is associated with type 2 diabetes, coronary heart disease and other causes of death. Since both parents influence obesity in their adult children, researchers recommend early intervention focusing on the whole family, particularly for overweight children with overweight parents.
Dr Silvia Costa, one of the study’s authors, said: “What’s striking is that we found parents’ weight to have such a long-term impact on their children’s weight, long after they have left home. Even in those who were not overweight as children, higher parental BMI significantly increased the risk of being persistently overweight during adulthood, even taking into account other factors known to influence obesity such as coming from a more deprived background or mother’s education.
“Further investigation is needed to unpick whether the influence of parents’ weight on their offspring is down to genetic influences, the home environment, shared habits like unhealthy eating or lack of exercise that their children may pick up and maintain through to adulthood, or a combination of all these factors.
“Our research reinforces the need for early intervention involving the whole family to prevent obesity before it starts, especially as the vast majority of people maintain excessive weight – whether they first become overweight during childhood or later during early adulthood.”
Additive influences of maternal and paternal body mass index on weight status trajectories from childhood to mid-adulthood in the 1970 British Cohort Study (2015) by Silvia Costa, William Johnson and Russell M Viner.
The paper is published as part of the Centre for Longitudinal Studies (CLS) Working Papers series. It will be available from the CLS website www.cls.ioe.ac.uk from 9am today (27 March) but journalists can request an advance copy. The paper will also appear in the Spring issue of the Longitudinal and Life Course Studies journal.
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