Obesity's Connection to Cardiovascular Disease Remains Poorly Understood

Obesity rates have escalated dramatically in the last several decades and the condition negatively affects health, but its connection to conditions such as cardiovascular disease (CVD) is complex and not fully understood. In the March issue of the Journal of Investigative Medicine experts say more research is needed to discover the links between obesity and CVD, with particular attention to biological differences between women and men.

The report stems from a multidisciplinary workshop of obesity and heart disease experts, convened by the Society for Women’s Health Research to address the National Institutes of Health Obesity Research Task Force’s report on the need for future research into obesity. The workshop focused on developing ideas for future research on sex differences in obesity and CVD.

“The task force report included sex as a population variable, but it did not explicitly recommend further research into biological sex differences in obesity and related diseases,” said Sherry Marts, Ph.D., one of the report’s authors and vice president of scientific affairs for the Society, a Washington, D.C., based advocacy organization. “We know that weight gain and fat deposition differ between women and men. Research into these differences can generate tremendous information about the development and progression of disease.”

The workshop participants developed three recommendations.

First, future research is needed to investigate adipose tissue (AT) composition and distribution. AT stores fat and responds to the body’s need for energy by mobilizing fat. AT also produces chemical signals that are involved in regulating appetite. Its distribution plays a major role in CVD risk.

In humans, the primary regions containing AT as subcutaneous fat are the hips, buttocks and thighs, while visceral fat is found in deeper deposits of the abdominal cavity. There is an important sex difference in AT distribution, as studies have shown that the storage of AT in visceral depots is linked to a higher risk of CVD in women. In other words, if a woman stores a lot of AT (and therefore a lot of visceral fat) around her waist, she may have an elevated risk of developing CVD. That theory is controversial, however, and some researchers believe that increased visceral fat is not a risk factor for CVD, but a marker of CVD’s progression in one’s body.

Another area that the experts agree requires further research is studies throughout the lifespan of women and men.

Appropriately designed longitudinal studies can help explain variances among women and men, different ethnicities and socioeconomic groups. These studies can examine sex differences in the critical periods of a woman’s life, especially those associated with dramatic hormonal change such as the onset of menstruation, pregnancy and menopause, which can impact the risk of weight gain, obesity and the development of other risk factors for CVD. Longitudinal studies may also shed light on why women experience CVD on average 10 years later than men.