TUESDAY, Jan. 12, 2010 (HealthDay News) -- Big-bottomed women, take heart.
Fat that settles around the thighs and buttocks may be better for you than a tummy tire, experts say. In fact, a new review of the data on the subject suggests it may even help protect your health.
"It is the protective role of lower body, that is, gluteofemoral fat that is striking," wrote a team of British researchers in the Jan. 12 online edition of the International Journal of Obesity. "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," they added.
In contrast, people with more tummy fat relative to lower-body fat -- often measured by waist-to-hip ratio -- are at a higher risk for cardiovascular disease, diabetes and other conditions related to obesity.
In fact, this measurement is even more predictive of heart disease than body mass index (BMI) alone, according to researchers at the University of Oxford.
"The authors have summarized a robust literature trying to defend the fact that if you put fat downstairs, particularly if you're a woman, there are potentially some health benefits," said Dr. Robert Eckel, an obesity expert and professor of medicine at the University of Colorado Denver School of Medicine.
The purpose of fat in general is to store energy for later use, a function more helpful in prehistoric times when feast-or-famine conditions reigned than in the current couch-potato, potato-chip era.
Typically, the "spare tire" of fat around the tummy can accumulate more easily than hind-quarters (gluteofemoral) fat, but as dieters know, it can also be metabolized away more quickly than fat around the bottom. On the other hand, fat settling around the derriere may be healthier than abdominal fat, because it helps lower levels of immune-system cells called cytokines, which promote inflammation, the experts said.
Inflammation is a major factor implicated in many diseases, particularly heart disease.
So while lower-body fat is harder to put on and take off, it doesn't release harmful cytokines, the researchers concluded.
Healthy people who are thick around the backside -- and these tend to be women -- also tend to have lower cholesterol, lower blood glucose levels and increased leptin levels than people who pack on weight around the abdomen, the British reviewers contend. Leptin is a hormone involved in regulating energy intake and expenditure.
Interestingly, buttocks fat in females more easily comes off only when the demand for energy is high, such as when breast-feeding.
Younger women are at a lower risk for heart disease than men until they reach menopause. And it's during this mid-life transition that women's body fat distribution tilts the other direction, the researchers noted.
In men, fat gravitates towards the center because the "male hormone" testosterone inhibits activity of lipoprotein lipase (LPL), an enzyme that plays a role in breaking down fat in the thigh.
But not everyone agrees with the notion that wide waists are harbingers of future heart disease, while big bottoms are comparatively harmless.
"The whole issue is very complex. We know that central adiposity [fat gain] is not good and that waist circumference is a predictor of cardiovascular disease," said Dr. Vasudevan A. Raghavan, assistant professor of internal medicine at Texas A&M Health Science Center College of Medicine and director of cardiometabolic and lipid clinic services at Scott & White Hospital in Temple. "We can hardly make the point that gluteofemoral fat is not without harm. At best, we know there's an association between gluteofemoral fat and overall favorable cardiovascular indices."
The best any individual can do is strive to have a normal body mass index and avoid excessive stomach fat, Raghavan advised.
There's more on obesity at the U.S. Centers for Disease Control and Prevention.