Recent research has shed new light on the link between body fat (adiposity) and the risk of developing cardiovascular disease. It answered some important questions and dispelled some presumptions. For many years the medical community and researchers have recognized the link between body fat and disease of the heart and arteries. There is no proof however that body fat is a cause of cardiovascular disease or that the link between the two is a general one that applies across the board.
The research, known as the Dallas heart study, consisted of 972 obese participants whose average age at the time of enrollment was 44 years. They did not have any evidence of cardiovascular disease at the time of enrollment and were followed in the study for 8.1 years. During the course of the study 91 cardiovascular events occurred in 68 of those enrolled. The cardiovascular events which occurred were deaths (from heart disease), heart attacks, strokes, heart failure and the onset of atrial fibrillation. Events also included episodes requiring bypass surgery of blocked arteries in the heart or limbs.
The researchers measured the abdominal visceral fat, abdominal subcutaneous fat and lower body fat of the participants using MRI and a technology known as dual energy x-ray absorptiometry. Abdominal visceral fat is the fat tissue within the abdominal cavity between and around the organs within the cavity. Those organs are the stomach, intestine, liver, bile tract, pancreas, spleen, kidneys, ureters, and adrenal glands. Subcutaneous abdominal fat is the fat (adipose) tissue within the abdominal cavity just beneath the skin. The lower body fat is that of the buttocks and hips.
After measuring adipose tissue in the sites mentioned above, mean (average) group calculations were made by dividing the sum of the measurements for all of the participants by the total number of individuals in the study.
Following appropriate statistical adjustments for age, sex, race, and conventional cardiac risk factors, the results of the study showed that obese individuals with excess amounts of abdominal visceral fat experienced cardiovascular events more frequently than the obese individuals who did not have excess fat between and around the organs within the abdomen.
More specifically the research findings showed that for each 1-standard deviation increase in the amount of abdominal visceral adipose tissue, there was a 24% step like increase in cardiovascular events. Therefore, the study concluded, the greater the amount of visceral fat, the greater the likelihood of developing cardiovascular disease.
The study findings did not show any effect of abdominal adipose tissue underneath the skin on the risk of developing cardiovascular disease, but did show that increased amounts of lower body fat were associated with fewer cardiovascular events. In fact, each 1-standard deviation increase in the amount of adipose tissue in the lower body was associated with a 27% decrease in the frequency of cardiovascular events. Therefore, the conclusion was that increased adipose tissue in the lower bodies of obese individuals protects against cardiovascular disease.
In recent years members of the scientific and medical communities have come to realize that body mass index (BMI) alone is not an adequate marker for the risk of cardiovascular disease. This fact explains why many individuals with increased BMIs do not develop cardiovascular disease.
In recent years, prior to the research under discussion, doctors and scientists have come to understand that obesity of the abdomen is associated with an increased risk of cardiovascular disease, whereas that primarily of the hips and buttocks is not. Therefore, reference has oftentimes been made to whether an obese individual has a pear-shaped body or an apple shaped body. That's because most of the fat in individuals with pear-shaped bodies is in the hips and buttocks, whereas that of individuals with apple shaped bodies is primarily in the abdomen. The problem with that distinction however, is that it does not account for abdominal visceral fat.
The research under discussion has brought the realization of the relationship between fat distribution and the risk of cardiovascular disease to a new level. After all, who would have thought a big butt reduces your chances of developing cardiovascular disease? The findings from this study have generated more questions than answers. Much more research is needed to answer some of the puzzling questions. But for now, suffice it to say - "the location of body fat is to the risk of heart disease as the location of real estate is to its value."
Victor E. Battles, M.D. is a board-certified internist with 30 + years of patient contact. He has been a principal investigator in several clinical research trials and is the founder of ProHealth Insight. For articles on health care visit Pro Health Insight..
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