A new study from Joslin Diabetes Centre has revealed that fat from certain areas of the body can actually reduce insulin resistance and improve insulin sensitivity.
The study led by Dr C. Ronald Kahn found that subcutaneous fat, found below the skin, usually in the hips and thighs is linked to decreased insulin levels and enhanced insulin sensitivity.
"This points to a new opportunity to find substances made by subcutaneous fat that may actually be good for glucose metabolism,'' said the researchers.
"If we can identify how subcutaneous fat does this, we will have a big clue as to where to look for these substances," they added.
Kahn said that obesity in the abdominal or visceral area, the classic "beer belly" or "apple" shape, increases diabetes risk and mortality.
However, it has been thought that obesity in subcutaneous areas, which is the "pear" shape, might decrease such risks.
"We started out to answer the basic question of whether fat inside the belly is bad for you because of where it is located, or is abdominal fat itself different from fat in other places," said Kahn, also an internationally recognized researcher in diabetes and metabolism.
The study was conducted using a mouse model wherein the mice were transplanted with fat deposits.
The researchers found that when subcutaneous fat was transplanted into the abdominal area, there was a decrease in body weight, fat mass, glucose and insulin levels and an improvement in insulin sensitivity. By contrast, transplantation of abdominal fat into either the abdominal or subcutaneous area had no effect.
"The surprising thing was that it wasn't where the fat was located. It was the kind of fat that was the most important variable. Even more surprising, it wasn't that abdominal fat was exerting negative effects, but that subcutaneous fat was producing a good effect," said Kahn.
"Animals with more subcutaneous fat didn't gain as much weight as they aged, had better insulin sensitivity, lower insulin levels and were improved all around," he added.
Previous studies in humans had shown that removal of subcutaneous fat by liposuction does not result in improvement of any aspect of metabolic syndrome. However, one human study did show that obese individuals with high levels of both intra-abdominal and subcutaneous fat were more insulin sensitive than those with only high levels of intra-abdominal fat.
Kahn said it is possible that subcutaneous fat may be producing certain hormones, known as adipokines, which produce beneficial effects on metabolism. These effects may offset the negative effects produced by abdominal fat.
The study appears in May issue of Cell Metabolism.