The more time people spend preparing meals, the greater their risk of health problems linked with heart disease, such as high blood pressure and high cholesterol, research suggests.
By contrast, those who cut back on the time spent on cooking reduce their risk of developing various conditions by more than a third, according to a study of more than 2,700 women.
Experts said the findings could partly be down to people eating bigger portions when they cook for themselves rather than buying convenience foods, such as snacks and ready-made meals.
Shop-bought meals could also have become healthier, they said.
Dr Brad Appelhans, of Rush University Medical Centre in Chicago, who led the study, suggested that health advice recommending home cooking be re-examined.
He said: “While the reasons underlying this association are still unclear, we think these findings indicate the need to revise our public health messaging, including the need to emphasize healthy cooking methods and to consider the potential benefits of healthy convenience meals.”
The researchers say little research has been done to examine the impact of home cooking on health.
They analyzed 14 years of data on 2,755 women aged 42 to 52.
They measured five markers of metabolic syndrome, the medical term for when someone has any three out of five factors that put people at greater risk of heart disease: obesity, fat levels in the blood, cholesterol, hypertension and blood glucose levels.
The risk of having metabolic syndrome increased over time, but the rise was greater among those who spent the most time on meals. In those who reduced their time cooking, the risk fell.