People with apple-shaped bodies have an increased risk of harmful high blood pressure in their kidneys, scientists have found.
Individuals with fat concentrated around their waist were already known to be extra prone to kidney disease. But the reason why was unclear.
The new research shows that being more apple-shaped is associated with blood flowing at a reduced rate but higher pressure through the kidneys.
"We found that apple-shaped persons - even if totally healthy and with normal blood pressure - have elevated blood pressure in their kidneys," said study leader Dr Arjan Kwakernaak, from the University Medical Centre Groningen in the Netherlands. "When they are also overweight or obese, this is even worse."
Raised blood pressure in the kidneys of apple-shaped people may be responsible for their increased risk of kidney disease in later life, he said.
Kidney hypertension can be successfully treated with salt restriction or certain drugs.
"Our current data suggest that such interventions could be particularly useful in subjects with a central body fat distribution," said Dr Kwakernaak.
Dr Kwakernaak's team studied 315 healthy individuals looking for links between hip-to-waist ratio and measurements of kidney function.
The research is published in the Journal of the American Society of Nephrology.