Differential health risks according to body shape

Obesity is reaching an epidemic proportion worldwide. Being obese is associated with increased risk of developing type II diabetes mellitus (DM) and cardiovascular disease (CVD). Previous studies of obesity have shown that individuals who have a selective excess of intra-abdominal (visceral) fat will be at a substantially higher risk of being insulin resistant and have a cardiovascular risk profile. In the body, fat tissue is a store for excess energy. The theory is that when extra energy is deposited as visceral fat and in ectopic depots such as the liver and skeletal muscle, this leads to an increased risk of DM and CVD. If the extra energy is deposited in subcutaneous depots and / or burned within the mitochondria in the liver and skeletal muscle, the individual, though obese, will be protected from these diseases. So can we find these people with metabolically benign obesity?

A study from University of Tubingen, Germany, examined a total of 314 individuals who underwent magnetic resonance (MR) tomography to measure total, visceral and subcutaneous fat, and proton MR spectroscopy to measure fat in the liver and skeletal muscle. The insulin sensitivity was estimated from oral glucose tolerance test. The intima-media thickness [IMT, it is used as an early marker of atherosclerosis (hardening of the artery)] of the common carotid artery (artery to the brain) was measured with ultrasound (Arch Intern Med 2008; 168: 1609 – 1616). There were 4 groups of individuals identified and assessed: normal weight [body mass index (BMI) < 25.0], overweight (BMI 25.0 – 29.9), obese insulin sensitive (OIS) (BMI ≥30, placement in the upper quartile of insulin sensitivity) and obese insulin resistant (OIR) (BMI ≥30, placement in the lower 3 quartiles of insulin sensitivity). Compared with the normal weight group, the overweight and obese groups have higher total body and visceral fat. Within the obese group of individuals, ectopic fat in the skeletal muscle and especially the liver and IMT values were lower in the OIS group when compared to the OIR group. The OIS group has higher insulin sensitivity than the OIR group. Interestingly, the insulin sensitivity and IMT values between the OIS group and normal weight group were not statistically different.

So is there a simpler way of identifying the metabolically benign obese people? Has no one made this observation until now because the MR machine was only invented recently? In 1956, a French clinician with a large obesity practice, published his clinical observations. In his practice, Dr Jean Vague observed that there were 2 predominant types of obese people: an upper-body, central abdominal obesity type which he called android and a lower-body, gluteal-femoral (buttocks and thighs) type which he called gynoid. He reported that patients with the upper-body, central abdominal form of obesity were prone to cardiovascular and metabolic complications such as hypertension, coronary artery disease and diabetes when compared to those having the lower-body, gluteal-femoral type. The designations android and gynoid applies to both men and women. These observations by Dr Vague seems to have gone unnoticed until the 1980s when large Scandinavian epidemiologic studies showed that CVD and death were related to the central body fat phenotype, as assessed by a high waist to hip ratio.

If you do not have an MR machine and do not know how to perform the oral glucose tolerance test, get a tape and measure your waist and hip circumference. Perform a simple mathematical calculation and you will have a rough idea if you have an android type or a gynoid type of habitus.

Even if you are a metabolically benign obese person, it would be wise not to think that you are in the clear and continue to eat as much as you want. In medicine, we are dealing with probabilities. We do not deal with absolute certainty like in rocket science. Thus, it is still a good idea for you to be normal weight rather than overweight or obese!