The Concept of CMR
Intra-abdominal Adipose Tissue: the Culprit?
Intra-abdominal (visceral) obesity (excess fat in the abdominal cavity) is closely linked to blood sugar and lipid problems that increase the risk of type 2 diabetes and coronary heart disease. Compared to normal weight individuals or obese subjects with low levels of intra-abdominal fat, obese patients with large amounts of intra-abdominal fat are characterized by high blood pressure, atherogenic dyslipidemia (elevated triglycerides and low levels of good HDL cholesterol), impaired glucose-insulin homeostasis (elevated blood glucose and a state of insulin resistance), and an inflammatory and pro-thrombotic (tendency to form clots in the blood, impeding blood flow) profile. Several studies have shown that a selective excess of intra-abdominal fat increases the risk of type 2 diabetes. The development of sophisticated imaging techniques has made it possible to accurately measure and distinguish intra-abdominal from subcutaneous fat (the fat located just under the skin). These non-invasive imaging techniques have also enabled researchers to conclude that, unlike intra-abdominal fat, subcutaneous fat is seldom associated with metabolic complications. It is unclear which factors influence whether dietary fat is stored under the skin or in the abdominal cavity. Variables such as age, gender, menopause, and ethnicity all influence where fat is stored.
It has been proposed that excess intra-abdominal fat may indicate that an individual’s subcutaneous adipose tissue is unable to serve as an “energy sink” for a calorie surplus resulting from excess energy intake and/or reduced energy expenditure. This inability may cause fat to accumulate at undesired locations, a phenomenon that has been described as ectopic fat deposition. Excess intra-abdominal fat may therefore be a “red light” or warning sign that excess energy is being stored as fat in unusual places, increasing the risk of diabetes and cardiovascular disease.