Jan. 12, 2010 -- Public health officials have harped on actively taking steps to reduce obesity, but it seems for some genetically lucky individuals, reducing their body fat isn't as important.
A new review published by researchers at the University of Oxford and Churchill Hospital in the United Kingdom suggests that people who carry their body fat in their thighs and backside aren't just carrying extra weight, but also some extra protection against diabetes, heart disease and other conditions associated with obesity.
"It is the protective role of lower body, that is [thigh and backside] fat, that is striking. The protective properties of the lower body fat depot have been confirmed in many studies conducted in subjects with a wide range of age, BMI and co-morbidities," the researchers write in the most recent issue of the Journal of Obesity.
"If you're going to have fat, you're definitely better off if you've got some fat in the lower body," said Dr. Michael Jensen, director of endocrine research at the Mayo Clinic in Rochester, Minn. "If you look at people who have primarily the pear shape, they're healthy in all the ways that this fat behaves. It's not just less heart attacks or less diabetes, it's all these ways we think about fat as an important organ for our health."
For years, researchers have looked into the idea that not all fat is created equal. People who carry their fat in their stomachs, also known as "apple-shaped" people, are said to have more problems from obesity than those who carry their fat in their hips
People who carry their fat in their thighs and backsides -- otherwise known as their gluteofemoral region -- appear to be in a similar class to those with fat in their hips.
"There's a lot of evidence that shows that the fat depots are not the same in the body," said Dr. Robert Kushner, a professor medicine specializing in obesity at Northwestern Memorial Hospital in Chicago.
He explained that the fat stored in the stomach is harmful because "it is more metabolically active," sending fatty contents and messages throughout the body, whereas fat in the lower regions of the body tends to be more stable and release fewer cytokines, which have been implicated in the insulin resistance that can lead to diabetes.
"There's a whole range of these hormonal markers that seem to be more preferentially released from the belly," said Kushner.
Getting More Back
But it is unclear if the fat in the thighs and backside are better for you than simply being thin, experts say.
"If you're a healthy thin weight, you're going to be every bit as healthy as someone who has weight, but has all the weight in the lower body," said Jensen.
But while lower body fat may be healthier than upper body fat, at this point people have little control over where their body chooses to store its fat, with spot-toning a myth and the only options coming from pharmaceutical side effects.
"You can't direct or drive the fat in one part of your body versus another," said Kushner. "For the average person on the street, it's determined by genetics."
He noted, however, that "One can develop, perhaps, medication to deposit in one area," a possibility noted by the authors of the review who point out that it is one effect of some existing diabetes drugs.
Different Fat, But Better Fat?
While the review seems to indicate that having fat lower down can be a good thing, not all experts are convinced.
"I think that the article makes a fairly compelling point that there are likely differences between these two fat stores," said Floyd Chilton, a professor of physiology and pharmacology at Wake Forest University Baptist Medical Center in Winston-Salem, N.C. "But I think it certainly falls short in making a convincing argument that one is protective and the other is the major source of the problem."
Some of the measurements, he explained, were not performed in a way that would allow for a conclusive judgment. For example, he said a number of studies cited by the researchers used hip circumference to determine where fat was being stored.
Chilton noted that many of the diseases discussed by researchers of the study -- including heart disease and diabetes -- have been connected to inflammation in the body.
"Many of them are increasing in incidence at a very similar rate to the dramatic increase in obesity," he said.
Getting the Skinny on Fat
While he is not yet sure that lower body fat can be said to be protective, Chilton said that recent years have shown that biomarkers have helped give a more nuanced picture of how the body regulates itself -- and how conditions like obesity really affect the body.
He gave leptin as an example, a recently discovered hormone found to have a role in regulating appetite -- and one that may be ignored by a more obese body.
"Leptin in particular is a fascinating one, because like insulin, people who are obese develop leptin resistance, where their brain is no longer responding to leptin," said Chilton.
It remains to be seen how much doctors can change about what these biomarkers are doing.