Losing 'protective' fat in thighs, buttocks good for the heart
Although past research has shown that thigh, hip and buttocks fat might actually protect against heart disease, a new study says losing fat in those areas is linked to better cardiovascular health.
The study, published Wednesday in the Journal of the American Heart Association, comes eight years after a well-publicized study in the International Journal of Obesity that showed fat in the thighs, hips and backside can help reduce the risk of heart disease and diabetes.
In the new study, an Australian researcher wanted to find out what happens if you lose that so-called "protective" layer of gluteofemoral fat and the nearby muscle.
"If you are a person who keeps most of your fat in these protective regions and you decide to lose weight, are you gaining any benefit from this weight loss? Or are you doing yourself harm in terms of cardiovascular disease?" said the study's author Dr. Peter Clifton, a professor of nutrition at the University of South Australia and a researcher at the National Health and Medical Research Council of Australia.
Conflicting results from past studies have left unanswered the question of how specific changes in the distribution of body fat affects cardiovascular risk. So, Clifton analyzed data from 399 participants in seven previously published diet-induced weight loss studies to see how losing thigh and backside fat and muscle would impact the risk of heart disease.
After looking at levels of glucose, insulin, total cholesterol, triglycerides, LDL cholesterol and blood pressure, he found that losing fat and muscle in the thighs, hips and buttocks was "directly associated" with beneficial changes in heart disease risk markers.
"The bottom line is that any weight loss – regardless of whether it is fat or lean, backside or abdomen – reduces cardiovascular risk factors," Clifton said. "For lowering cholesterol, losing leg fat is just as important as losing abdominal fat."
The study also found there's no harm in losing lean tissue – or muscle – in the thighs, hips and backside. "I found that quite interesting," Clifton said.
Doctors should not "worry about getting patients to exercise to minimize their muscle loss. … You can just focus on losing weight first. Then when [patients] are lighter, get them to increase exercise," he said.
Dr. Robert Eckel, an endocrinologist and physician-scientist at the University of Colorado Anschutz Medical Campus, said he found the study's overall results somewhat surprising.
"In general, weight loss that is more abdominal is felt to be more favorable for cardiovascular disease risk, compared to peripheral weight loss, meaning in the legs and arms," said Eckel, who was not involved in the study.
Today, about four in 10 American adults are obese, according to data released in March from researchers at the Centers for Disease Control and Prevention. The condition puts them at higher risk for high blood pressure, diabetes, stroke and heart disease.
Eckel said that while additional studies are needed to learn more about fat distribution, "the message we really want to give the public is weight loss is good for you, and losing a few pounds isn't enough," he said.
Guidelines recommend that overweight and obese patients should lose at least 5 percent to 10 percent of their body weight to have a positive impact on blood pressure, glucose tolerance, diabetes control and cholesterol.
"The cardiovascular benefit of the 5 to 10 percent weight loss is proven," Eckel said.
K N Manolopoulos et al. Gluteofemoral body fat as a determinant of metabolic health, International Journal of Obesity (2010). DOI: 10.1038/ijo.2009.286