Middle-age spread far more likely if both parents obese

“Children whose parents lived with obesity are much more likely to be living with obesity themselves when they are in their forties and fifties, long after they have left home.”

Middle-aged adults are six times more likely to be obese if their own parents were, according to a study showing how it can be passed down generations.

The chance of people being obese in their forties and fifties is largely determined by the weight of their parents when they were children, the findings suggest.

Researchers looked at data from more than 2000 families in Norway, who were tracked for three decades.

Parents had their weight measured in 1994-95 when they were aged 40 to 59, and their children had their weight measured when they reached the same age, in 20152016.

If both parents were obese, their offspring were six times more likely also to be obese in middle age, compared with parents who had a healthy weight.

Having just one parent who was obese tripled the odds.

The study is the first to show how obesity in adulthood is “transmitted between generations”, which scientists said was the result of a combination of lifestyles and genetics.

One in four adults in the United Kingdom are obese, while one in five children are classed as obese by the time they leave primary school. Previous research has shown that childhood obesity is strongly linked to the weight of a child’s parents.

This is largely thought to be because of shared family lifestyles, with children adopting similar eating and exercise habits to their parents when they live under the same roof. Shared genes also play a role: some families have genes which make it harder to resist unhealthy food, so they are more likely to gain weight.

Dr Mari Mikkelsen, of the Department of Community Medicine at UiT Arctic University of Norway, the author of the study, said: “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.

“We found that this is indeed the case: children whose parents lived with obesity are much more likely to be living with obesity themselves when they are in their forties and fifties, long after they have left home. 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.

“It also lays the foundation for research into factors that influence the intergenerational transmission of obesity and that can be targeted to prevent offspring from spending their whole life affected by obesity.”

The research, which will be presented at the European Congress on Obesity in Venice in May, involved 2068 families from the Tromso Study, ongoing research to track Norway’s population. – The Times

Dr Mari Mikkelsen