People genetically prone to obesity could be more likely to pile on weight from fried foods than those with lower risk, a study suggests.
Eating fried food four times a week or more had twice as big an effect on weight for those with high genetic obesity scores compared to those with the lowest, Harvard researchers found.
Even eating the foods once or twice a week increased the risk of being overweight if people had a genetic predisposition to obesity.
It is the first time experts have looked at the interaction between obesity genetics, weight (measured as body mass index or BMI) and a certain food group.
The team analysed data from more than 37,000 men and women taking part in three US health trials.
Using questionnaires, they looked at food consumption at home and away and calculated a genetic risk score based on 32 known genetic variants associated with BMI and obesity.
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Those in the highest third of genetic risk had twice the difference in BMI if they ate fried food four times a week or more compared to those with the lowest risk.
Meanwhile, those with the highest risk who ate the foods one to three times a week were also heavier than people with lower genetic risk.
Writing in the British Medical Journal (BMJ), the authors, including from the Harvard School of Public Health and Harvard Medical School in Boston in the US, said: "We found a significant interaction between fried food consumption and genetic predisposition to adiposity (obesity).
"These results for the first time suggest that individuals with a greater genetic predisposition to adiposity might be more susceptible to the adverse influence of overconsumption of fried food on adiposity; and overconsumption of fried foods might magnify genetic effects on adiposity."
Assistant professor Lu Qi, from the Harvard School of Public Health, added: "Our findings emphasise the importance of reducing fried food consumption in the prevention of obesity, particularly in individuals genetically predisposed to adiposity."
Professor Alexandra Blakemore and Dr Jessica Buxton, from Imperial College London, said in an accompanying editorial: "This work provides formal proof of interaction between a combined genetic risk score and environment in obesity.
However, they said the results "are unlikely to influence public health advice, since most of us should be eating fried food more sparingly anyway."